EP3338914A1 - Method for the endless manufacture of a coiled hot rolled sheet in a combined casting and rolling installation, method for starting up a combined casting and rolling installation, and a combined casting and rolling installation - Google Patents

Abstract

The invention relates to a method for the endless production of a wound hot strip (15) in a cast-rolled composite plant. The object of the is to provide a generic method, can be produced inexpensively with the high quality hot strip (15) of different grades of steel. The process should also be reliable and cause extremely low operating costs. This object is achieved by a method according to claim 1.

Description

Field of engineering

The present invention relates to the technical field of cast-rolled composite plants. These are plants in which a continuous casting plant for the continuous production of a steel strand with a slab format, eg thin or medium slabs, is connected directly and inline with a rolling train for hot rolling of a hot strip. The hot strip is cooled after the rolling mill in a cooling section and then discharged, for example by winding the band to coils (English coils ). In the literature, these systems are also known, for example, under TSCR ( Thin Slab Casting and Rolling ) or Arvedi ESP systems.

In particular, the invention relates to endlessly operated cast-rolled composite installations in which the casting installation is designed as a thin-slab continuous casting installation ( TSER T towards S lab Endless R olling ). The continuous thin slab strand continuously produced in the thin slab continuous casting plant is fed directly, inline and uncut to the rolling train where it is rolled into an endless hot strip. After the rolling train, the strip is again cooled in a cooling section, then cut for the first time to a specific length or weight and wound into coils.

State of the art

Although an Arvedi ESP system is already much more compact than a CSP or a QSP system with a tunnel kiln, as well as operating costs and CO ₂ output per ton As hot-rolled strip has also been greatly reduced, there is a need for even more compact cast-and-strip composite plants for producing one-year hot-rolled strip production in the range of 1 million tons and less.

The solutions currently on the market, such as a continuous casting line with a downstream broadband line, an Arvedi ESP, Danieli QSP-DUE or SMS CSP / CEM system, are not compact enough for these low volumes and / or due to much higher annual production volumes of about 2.5 million tonnes and the high capital investment CAPEX with an annual production volume of about 1 million tons and less not economically operable. Thus, especially for small steel mills, there is a need for a compact cast-and-roll composite plant that is inexpensive to purchase and operate, yet capable of producing high quality hot strip of various grades of steel.

Two-roll strip casters with a downstream rolling mill are also known from the prior art. Although a two-roll strip caster is very compact and produces a strip immediately, this technology has not been able to prevail until now, since in particular medium to higher alloyed steel grades can not be reliably produced.

From the WO 97/36699 is a concept for the continuous operation of a cast-rolling composite system known. The temperature of a thin slab strand produced in a continuous casting plant is homogenized in a compensation furnace, the thin slab strand then descaled, rolled in a seven-stand rolling mill, cooled and wound up. The document indicates that, starting from a specific throughput h ₀ * v _C of h ₀ * v _C > 0.487 m ² / min, the hot strip can be finish-rolled from the casting heat of the thin slab strand in the austenitic state. However, in the case of relatively thin thin slab strands, this concept requires very high casting speeds, for example with a slab thickness of 50 mm a casting speed of about 10 m / min. In industrial practice it has been found that casting speeds v _c > 6 m / min are problematic because the reliability of the continuous casting machine decreases significantly. Attempting to achieve the specified specific throughput by using relatively thick slabs, for example, with a slab thickness of 100 mm by a casting speed of about 5 m / min, this leads to reliable conditions in the continuous casting, but the mill has many scaffolding (high CAPEX) to produce a hot strip with a thickness <10 mm can. In practice, it has also been found that the pre-rolled pre-strip typically needs to be reheated after 3 or 4 passes. Thus, today's cast-and-roll compound plants are usually operated at a casting speed of 5, 6 or 7 m / min and the pre-strip is reheated in an induction furnace. Due to the intermediate heating but increase the operating costs (OPEX). Accordingly, there is a need for a low cost and low cost cast-compound (low CAPEX) system that can be reliably operated on the one hand and does not require intermediate heating (low OPEX) but still produces a high quality hot strip of 2.5 to 10 gauge mm finish austenitic state.

How this problem can be solved is not apparent from the prior art.

Summary of the invention

The object of the invention is to overcome the disadvantages of the prior art and to provide a method for the endless production of a hot strip of steel in a cast-rolling composite plant and a compact, favorable cast-rolling composite plant of the type mentioned, with which high quality hot strip of different steel grades (low, medium and high carbon, but also HSLA, API grades, etc.) can be produced inexpensively. The Process should be extremely reliable and cause extremely low operating costs. The cast-rolled composite plant according to the invention should be significantly cheaper than comparable ESP / QSP / CSP plants. In addition, a simple method for starting a cast-rolling compound system should be specified so that the system can be approached quickly and reliably.

This object is achieved by a method for endless production of a coiled hot strip of steel in a cast-rolling composite plant according to claim 1. Advantageous embodiments are the subject of the dependent claims.

• Stranggießen einer Stahlschmelze in einer Durchlaufkokille der Stranggießanlage zu dem Dünnbrammenstrang, wobei der Dünnbrammenstrang beim Austritt aus der Durchlaufkokille einen flüssigen Kern, eine Dicke von 45 bis 70 mm, bevorzugt 55 bis 65 mm, und eine Breite von 900 bis 2300 mm, bevorzugt 1100 bis 1900 mm, aufweist;
• Stützen, Führen und Dickenreduzieren des Dünnbrammenstrangs in einer Strangführung der Stranggießanlage, wobei der dickenreduzierte Dünnbrammenstrang eine Dicke h von 35 bis 52 mm, bevorzugt 40 bis 50 mm, eine Gießgeschwindigkeit V_C und einen spezifischen Durchsatz D = h.v_C von 0,45 m²/min ≥ D ≥ 0,27 m²/min aufweist;
• Warmwalzen des endlosen, dickenreduzierten Dünnbrammenstrangs in der Walzstraße, wobei der Dünnbrammenstrang aus seiner Gießhitze heraus durch zumindest drei, bevorzugt durch vier, Walzstiche zu dem Warmband mit einer Dicke von 2,5 bis 10 mm gewalzt wird und der letzte Walzstich im austenitischen Temperaturbereich des Stahls erfolgt;

• Abkühlen des Warmbands in der Kühlstrecke;
• Querteilen des abgekühlten Warmbands; und
• Aufwickeln des Warmbands zu Bunden in der Wickeleinrichtung.

Specifically, the object of the invention is achieved by a method for endless production of a coiled hot strip of steel in a cast-rolling composite plant, wherein the cast-rolling composite plant a continuous caster for producing an endless thin slab strand, a rolling mill with multiple rolling stands for hot rolling of the thin slab strand to the hot strip, a cooling line for cooling the hot strip, a pair of shears for cutting the hot strip and a winding device for winding the hot strip, comprising the steps of:

• Continuous casting of a molten steel in a continuous casting mold of the continuous casting plant to the thin slab strand, wherein the thin slab strand at the exit from the continuous casting mold a liquid core, a thickness of 45 to 70 mm, preferably 55 to 65 mm, and a width of 900 to 2300 mm, preferably 1100 to 1900 mm;
• Supporting, guiding and reducing the thickness of the thin slab strand in a strand guide of the continuous casting, wherein the thickness-reduced thin slab strand has a thickness h of 35 to 52 mm, preferably 40 to 50 mm, a casting speed V _C and a specific throughput D = hv _C of 0.45 m ² / min ≥ D ≥ 0.27 m ² / min ;
• Hot rolling the endless, reduced thickness thin slab strand in the rolling mill, wherein the thin slab strand out of its casting heat by at least three, preferably four, rolling passes are rolled to the hot strip having a thickness of 2.5 to 10 mm and the last pass is made in the austenitic temperature range of the steel;

• Cooling the hot strip in the cooling section;
• Cutting the cooled hot strip; and
• Winding the hot strip to coils in the winding device.

The aforementioned continuous casting mold is designed either straight or arcuate. However, a straight-through mold is preferred because impurities in the molten steel can be taken up by the casting powder and thus the internal quality of the thin slab strand is improved.

In the continuous casting mold, a thin-slab strand is formed with a liquid core which has a thickness of 45 to 70 mm, preferably 55 to 65 mm, and a width of 900 to 2300 mm, preferably 1100 to 1900 mm, on leaving the through-mold. The thin slab strand is supported, guided and reduced in thickness in the strand mold subsequent to the continuous casting mold, so that the thickness-reduced thin slab strand has a thickness h of 35 to 52 mm, preferably 40 to 50 mm and a specific throughput D = hv _C of 0.45 m ² / min ≥ D ≥ 0.27 m ² / min . Thickness reduction can advantageously take place in the case of liquid (so-called liquid core redcution ) or partially liquid core (so-called soft core reduction ) of the thin-slab strand . It is noteworthy in the process according to the invention for the continuous production of a wound hot strip that, as stated in the prior art, the highest possible throughput through the continuous casting plant is advantageous, but a mean specific throughput D between 0.27 and 0.45 m ² / min is sought. This ensures that the continuous casting plant works reliably. The continuous thin slab strand is after the thickness reduction without being previously descaled or heated, ie exclusively from its casting heat out in the rolling mill through several, preferably rolled by at least three, more preferably by four, rolling passes to the hot strip with a thickness of 2.5 to 10 mm, wherein the last rolling pass takes place in the austenitic temperature range of the steel. Thus, the hot strip on an austenitic structure. Subsequently, the hot strip is cooled in the cooling section, transversely divided by the scissors and wound into coils in the winding device.

So that the energy content of the thickness-reduced thin slab strand can be set as accurately as possible, it is advantageous if a control or regulating device of the continuous casting using a mathematical model an actual position of a sump tip along the transport path of the thin slab strand in the strand guide and an actual temperature profile along the transport path of the thin slab strand in the strand guide and preferably in normal planes to continuously calculated and the thin slab strand is continuously cooled, taking into account a target position of the sump tip in the strand guide, so that the actual position of the sump tip of the desired position corresponds as possible. It is advantageous if the actual position of the sump tip lies in the last third of the arcuate region of the strand guide or in the horizontal outlet region of the strand guide.

The temperature of the hot strip at the last pass can be accurately adjusted when the actual temperature T _{1Ist of} the hot strip after the last pass in the rolling line and before cooling in the cooling section is measured and the cooling of the thin slab strand in the strand guide and / or the casting speed v _{c is} set regulated, so that the actual temperature T _1Ist a target temperature T _1Soll corresponds as possible.

The _coiling temperature of the hot strip can be accurately adjusted when the actual temperature T _{2Ist of} the endless hot strip is measured after cooling in the cooling section, and Cooling nozzles of the cooling section are controlled temperature-controlled, so that the actual temperature T _2Ist a target temperature T _2Soll corresponds as possible.

In order to reduce the thickness of the hot strip and to improve its surface quality, it is favorable if a bunch is then pickled and cold rolled to a thickness of 0.3 to 7 mm by several rolling passes in a cold rolling mill.

• Angießen der Stranggießanlage, wobei ein Kaltstrang, der eine Durchlaufkokille der Stranggießanlage fluiddicht abdichtet, in Transportrichtung aus der Durchlaufkokille ausgezogen wird;
• Stützen und Führen eines dem Kaltstrang nachfolgenden Dünnbrammenstrangs in einer Strangführung der Stranggießanlage;
• Passieren der Walzgerüste der Walzstraße, wobei der Kaltstrang die Walzstraße ungewalzt passiert;
• optional Abkühlen des ungewalzten Dünnbrammenstrangs in der Kühlstrecke;
• Abschneiden des Kaltstrangs durch die Schere;
• Ausfördern des Kaltstrangs, wobei der Kaltstrang vorzugsweise die Wickeleinrichtung passiert und in Transportrichtung hinter der Wickeleinrichtung abgelegt wird;
• Querteilen des ungewalzten Dünnbrammenstrangs in ein Häckselgut durch die Schere und Ausfördern des Häckselguts;
• optional Erhöhen einer Gießgeschwindigkeit und Dickenreduzieren des Dünnbrammenstrangs in der Strangführung;
• Anstellen der Walzgerüste an den Dünnbrammenstrang und Warmwalzen des Dünnbrammenstrangs zu einem Warmband;
• Abkühlen des Warmbands in der Kühlstrecke;
• Querteilen des abgekühlten Warmbands; und
• Aufwickeln des Warmbands zu Bunden in der Wickeleinrichtung.

When starting the cast-rolling composite plant, a continuous casting machine for producing an endless thin slab strand, a rolling mill with multiple stands for hot rolling of the thin slab strand to the hot strip, a cooling section for cooling the hot strip, a scissors for cutting the hot strip and a winding device for winding the Hot-rolled strip, the following steps are performed:

• Casting the continuous casting plant, wherein a cold strand, which seals a continuous casting mold of the continuous casting machine in a fluid-tight manner, is pulled out in the transport direction from the continuous casting mold;
• Supporting and guiding a thin slab strand following the cold strand in a strand guide of the continuous casting plant;
• Passing the rolling mills of the rolling train, the cold train passing the rolling train without being rolled;
• optional cooling of the non-rolled thin slab strand in the cooling section;
• Cutting the dummy bar by the scissors;
• Feeding the cold strand, the cold strand preferably passes through the winding device and is stored in the transport direction behind the winding device;
• Cutting the unhardened thin slab strand into a shredded material by the shears and conveying out the shredded material;
• optionally increasing a casting speed and thickness reduction of the thin slab strand in the strand guide;
• Setting the rolling stands to the thin slab strand and hot rolling the thin slab strand into a hot strip;
• Cooling the hot strip in the cooling section;
• Cutting the cooled hot strip; and
• Winding the hot strip to coils in the winding device.

Initially, the cold strand is introduced into the through mold either in the transport direction ( top feeding ) or counter to the transport direction of the thin slab strand ( bottom feeding ), so that it seals the mold fluid-tight. By casting the continuous casting plant, a thin slab strand is formed in the continuous casting mold, which is welded to the head of the cold strand. The cold strand incl. The subsequent thin slab strand is then removed from the mold and supported in the strand guide and out. In order to prevent damage to the rolling stands by the cold strand or the relatively cold thin slab strand, the rolling stands against the setting for rolling a hot strip with a thickness between 2.5 and 10 mm are driven, so that the cold strand can pass through the mill without being rolled. Otherwise, it is of course also possible that the rolling stands are started up before starting. Thereafter, the cold strand is cut off from the subsequent thin slab strand by the scissors and discharged the cold strand from the roller table between the scissors and the winding device or the winding devices. This can be done in a particularly simple manner by accelerating the cold strand by driven roller blocks and depositing it on the roller table in the transport direction behind the winding device. At least the unrolled thin slab strand is then chopped into a shredded material by the shears and the shredded material is discharged. The conveying out can take place in that the shredded material is introduced into a scrap bucket below the roller table. Subsequently, it is advantageous if the casting speed of the continuous casting plant is increased stepwise, in particular to a specific throughput D with D = hv _C of 0.45 m ² / min ≥ D ≥ 0.27 m ² / min, and the thin slab strand in the strand guide of the continuous casting machine is reduced in thickness by strand guide rollers that can be hydraulically set to the strand. Finally, the rolling stands are set to the thin slab strand, so that the thin slab strand is rolled into a hot strip, the hot strip is then cooled, transversely divided and wound up.

It is clear to the person skilled in the art that the transport direction in the continuous casting plant changes from the vertical direction via an arcuate section into the horizontal and follows the flow of material through the installation.

• eine Stranggießanlage, die eine Durchlaufkokille zur kontinuierlichen Herstellung eines Dünnbrammenstrangs, der einen flüssigen Kern, eine Dicke von 45 bis 70 mm und eine Breite von 900 bis 2300 mm beim Austritt aus der Durchlaufkokille aufweist, und eine Strangführung zum Stützen, Führen und Dickenreduzieren des Dünnbrammenstrangs mit einer Sekundärkühlung zum Abkühlen des Dünnbrammenstrangs, wobei der Dünnbrammenstrang nach der Dickenreduktion eine Dicke von 35 bis 52 mm, , bevorzugt 40 bis 50 mm, eine Gießgeschwindigkeit v_c und einen spezifischen Durchsatz 0,45 m²/min ≥ D ≥ 0,27 m²/min aufweist, umfasst;
  • eine Walzstraße zum Warmwalzen des dickenreduzierten Dünnbrammenstrangs, wobei die Walzstraße zumindest drei, bevorzugt genau 4, Walzgerüste aufweist und durch das Warmwalzen ein Warmband mit einer Dicke von 2,5 bis 10 mm erzeugt wird;
  • eine Kühlstrecke zum Abkühlen des Warmbands;
  • eine Schere zum Querteilen des abgekühlten Warmbands; und
  • eine Wickeleinrichtung zum Aufwickeln des Warmbands zu Bunden.

A simple, extremely compact and inexpensive cast-rolled composite plant for the production of a hot strip made of steel has:

• a continuous casting machine comprising a continuous casting mold for continuously producing a thin slab strand having a liquid core, a thickness of 45 to 70 mm and a width of 900 to 2300 mm at the exit from the continuous casting mold, and a strand guide for supporting, guiding and reducing the thickness of the thin slab strand with a secondary cooling for cooling the thin slab strand, wherein the thin slab strand after the thickness reduction, a thickness of 35 to 52 mm, preferably 40 to 50 mm, a casting speed v _c and a specific throughput 0.45 m ² / min ≥ D ≥ 0.27 m ² / min comprises;
  • a rolling line for hot rolling the reduced thickness thin slab strand, wherein the rolling mill has at least three, preferably exactly 4, rolling stands and hot rolling produces a hot strip having a thickness of 2.5 to 10 mm;
  • a cooling section for cooling the hot strip;
  • a pair of scissors for cutting the cooled hot strip; and
  • a winding device for winding the hot strip into coils.

For the compactness of the continuous casting plant, it is favorable if an arcuate section of the strand guide has a radius of curvature R of 4.5 to 6.5 m, preferably 5 to 6 m.

In order not to undercool the edge regions of the thin slab strand, it is favorable if the secondary cooling has at least two spray nozzles which can be moved in a width direction of the thin slab strand at several positions within the strand guide.

In order to take as much casting heat as possible from the continuous casting plant into the rolling train, it is advantageous if in the area between the end of a horizontal section of the strand guide and the first stand of the rolling train thermal insulation panels (so-called encopanels or heat covers ), preferably a thermal tunnel, are attached.

In addition, it has proven to be advantageous if the horizontal distance between two rolling stands of the rolling mill is between 3 and 6 m, in particular between 4 and 5 m, and / or the length of the cooling section between 10 and 60 m.

Finally, it is favorable if a lifting device is arranged between the pair of scissors and a pair of drive rollers, wherein the hot strip can be clamped by the drive rollers and the hot strip can be lifted by the lifting device, whereby the hot strip can be pulled away from the scissors. In a so-called cobble in the cast-rolled composite plant, the hot strip is first separated by the shears, then clamped in the transport direction behind the scissors hot strip by drive rollers and lifted by the lifting device. As a result, the hot strip is pulled away from the scissors, so that a collision with the subsequent hot strip is prevented.

Brief description of the drawings

• Fig 1 eine schematische Darstellung einer Gieß-Walz-Verbundanlage
• Fig 2 eine Darstellung der Stranggießanlage aus Fig 1
• Fig 3 eine Darstellung der unterschiedlichen Abschnitte der Strangführung der Stranggießanlage
• Fig 4 eine Darstellung mehrerer breitenverstellbarer Spritzdüsen in der Strangführung der Stranggießanlage
• Fig 5 eine Darstellung eines Temperaturverlaufs bei der erfindungsgemäßen Herstellung eines dünnen, warmgewalzten Fertigbands in einer Gieß-Walz-Verbundanlage
• Fig 6a und 6b je eine Darstellung einer Vorderansicht einer Hubeinrichtung in einem nicht angehobenen und einem angehobenen Zustand
• Fig 7a bis 7e die Schritte beim Anfahren einer erfindungsgemäßen Gieß-Walz-Verbundanlage

Further advantages and features of the present invention will become apparent from the description of non-limiting embodiments. The following schematically illustrated figures show:

• Fig. 1 a schematic representation of a casting-rolling compound system
• Fig. 2 a representation of the continuous casting from Fig. 1
• Fig. 3 a representation of the different sections of the strand guide the continuous casting
• Fig. 4 an illustration of several width-adjustable spray nozzles in the strand guide of the continuous casting
• Fig. 5 a representation of a temperature profile in the inventive production of a thin, hot-rolled finished strip in a cast-rolling composite plant
• 6a and 6b depending on a representation of a front view of a lifting device in a non-raised and a raised state
• 7a to 7e the steps when starting a cast-rolled composite plant according to the invention

Description of the embodiments

The Fig. 1 schematically shows a cast-rolled composite plant according to the invention for the production of a hot-rolled hot strip of steel. The liquid steel pretreated by a vacuum treatment with a hydrogen content ≤ 1 ppm is placed in pans to the ladle turret (in Fig. 2 is shown at the top left hinged in the ladle pan 8 shown) of the continuous casting 1 transported and there formed by a Gießverteiler 9 in the funnel as mold Continuous mold 2 cast. In the continuous casting mold 2, a thin slab strand is formed with a thin strand shell having a thickness of 55 mm and a width of 1700 mm. The partially solidified thin slab strand is pulled out of the continuous casting mold 2 continuously and supported in the following strand guide 4, guided and by spray nozzles (see Fig. 4 , Reference numeral 19) of a secondary cooling further cooled. The strand guide 4 has a vertical portion 4a, an arcuate portion 4b having a plurality of strand guide segments, and a horizontal portion 4c (see FIG Fig. 3 ). In Fig. 2 two strand guide segments 6 are shown. Each strand guide segment 6 has in each case a plurality of strand guide rollers that can be hydraulically attached to the thin slab strand 3, as a result of which the thin slab strand 3 is reduced to a thickness of 45 mm. In the thickness reduction , the thin slab strand 3 preferably has a liquid core 5 (in what is known as a liquid core reduction ) or a partially liquid core. In order to keep the mechanical Verforumungsarbeit as low as possible in the subsequent rolling steps in the rolling train 14 and to hold the casting heat in the thin slab strand 3, the secondary cooling in the strand guide 4 and the casting speed v _{C is set} by a control or regulating device 20 of the continuous casting 1, that the thin slab strand 3 solidifies at a predetermined position within the strand guide 4 (see Fig. 3 ). The continuous caster 1 is operated at a casting speed v _C of 6 m / min and at a specific throughput D = hv _C = 0.27 m ² / min .

The controlled by the control or regulating device 20 or controlled operation of the continuous casting 1, so that the sump tip (ie, the Durcherstarrungspunkt) of the thin slab strand 3 comes to rest at a predetermined position within the strand guide 4, for example, from WO 01/03867 A1 known. The corresponding disclosure is hereby incorporated by reference into this application. The reduced thickness, solidified, non-descaled and endless thin slab strand 3 is rolled immediately after continuous casting through four rolling stands F1 ... F4 of the rolling train 14 into a hot strip having a thickness of 3.2 mm (see the following table with the individual thickness decreases and average temperatures ). Tab. 1 before F1 after F1 after F2 after F3 after F4 Thickness [mm] 45 19 9 4.5 3.2 Ø temperature [° C] 1090 1040 950 885 830

The hot strip is then cooled by a cooling section 16 to winding temperature, cut by the scissors 17 and wound up by one of the winding devices 18 into coils.

Should a problem occur in the rolling train 14 or the cooling section 16, the hot strip is cut off by the scissors 17, the hot strip section lying in the transport direction behind the scissors 17 by driver rollers (eg a pair of drive rollers 18 a of the winding devices 18) clamped and the foot of the hot strip section through the Lifting device 10 pulled away from the scissors 17. The hot strip coming from the rolling line 14 is chopped by the shears 17 into short sections of hot strip, e.g. carried out by means of scrap buckets 11.

In Fig. 2 further details of the continuous casting 1 are shown.

The Fig. 3 shows the vertical portion 4a, the arcuate portion 4b and the horizontal portion 4c of the strand guide 4 of the continuous casting 1 closer. Due to the straight through mold 2 and the vertical section 4a, inclusions in the molten steel accumulate on the meniscus, these are taken up by the casting powder and used in the form of casting slag for strand lubrication. The radius R of arcuate strand guide 4b is in Fig. 3 shown and is in the continuous casting machine according to the invention about 5 m. The thin slab strand 3 enters immediately (ie without being descaled) after the horizontal section 4c into the first rolling stand F1 of the rolling train. Furthermore, the figure shows how a thin slab strand 3 with a liquid core 5 leaves the continuous casting mold 2 and is reduced in thickness in the strand guide 4. The thickness-reduced thin slab strand 3 is pulled out of the continuous casting mold 2 by a drawing-out device 7 designed as a pair of driven strand guiding rolls. In order to keep the sump tip of the thin slab strand 3 at a certain position, the casting speed v _c , optionally also the thickness reduction of the thin slab strand 3 by the strand guide segments 6, is controlled by the control device 20.

In Fig. 4 a width-adjustable secondary cooling in the strand guide 4 is shown. In both narrow 3 and wide thin slab strands 3 'overcooling of the edge portions of the strand 3 is prevented by the outer two spray nozzles 19 are formed displaceable both in the width direction and normal to the strand surface. The spray nozzles 19 are connected via spray nozzle holders 21, 21 'to a linear drive 22, which shifts the spray nozzles 19 in the axial direction of the linear drive 22. The central spray nozzle 19 can either be fixed or as shown, also designed to be displaceable.

In Fig. 5 is the temperature profile in ° C in the inventive production of a hot-rolled hot strip shown in a cast-rolling composite plant according to the invention; The figure corresponds to the above description and the information in Table 1. The core temperature is dotted, the surface temperature is dashed and the average temperature shown in solid. A grade DD11 molten steel is subjected to a vacuum treatment prior to continuous casting, whereby the hydrogen content in liquid steel is reduced to ≤ 1 ppm. In the continuous casting mold 2 of the continuous casting plant 1, a partially solidified thin slab strand 3 having a thickness of 55 mm and a width of 1700 mm is formed and reduced in thickness by a liquid core reduction to a solidified thin slab strand 3 with a thickness of 45 mm. The solidified thin slab strand 3 leaves the horizontal section 4c of the continuous casting plant 1 with a casting speed of v _C = 6 m / min and thus with a specific throughput D = hv _C = 0.27 m ² / min. The solidified thin slab strand 3 is supplied without being descaled to a rolling train 14 and reduced there by four rolling stands F1 to F4 to a thickness of 3.2 mm. It is noteworthy that, even at the very low specific throughput of D = 0.27 m ² / min, the last roll pass in the rolling stand F4 takes place in the austenitic state of the steel. Subsequently, the hot strip is cooled in the cooling section 16, cut and wound into coils.

The Fig. 6a shows the lifting device 10 Fig. 1 in a not raised and in Fig. 6b in a raised state. In the non-raised state, all the underlying roller table rollers - including the two liftable lifting rollers 13 - form a horizontal roller table 12. If, as in the description too Fig. 1 Outlined, a problem occurs during or after continuous operation in the rolling mill 14, the endless hot strip is cut by the scissors 17, clamped and the two lifting rollers 13 are moved upwards (see the raised state in Fig. 6b ). Since the hot strip 15 is clamped at a position behind the scissors 17, the foot of the hot strip section is pulled away from the scissors 17. This avoids a collision between the pulled-away hot strip section and the hot strip following from the rolling train 14 in a simple manner.

The FIGS. 7a to 7e schematically show the process steps when starting a cast-rolled composite plant according to the invention.

The Fig. 7a shows the cast-rolled composite plant before the start of casting the continuous casting. The continuous casting mold 2 is sealed in a fluid-tight manner by a cold strand 30 which comprises a cold strand head 31 and a link chain 32. After casting the continuous caster 1, the cold strand 30 is pulled out of the cooled continuous casting mold 2 by driver rolls 18a in the transport direction T. By casting the cold strand head 31 welded to the subsequent thin slab strand 3 (see Fig. 7b ), wherein the thin slab strand 3 is supported by the strand guide 4 (usually of strand guide rollers of a strand guide segment 6), guided and further cooled by a secondary cooling.

In Fig. 7b the cold leg 30 is already largely pulled out of the continuous casting 1. Since the cold strand 30 is substantially colder and harder than the following thin slab strand 3, the rolling stands F1 ... F4 of the rolling train 14 are in an ascended state, so that the cold strand 30 can pass the rolling train 14 without being rolled. This prevents damage to the work rolls of the rolling stands F1 ... F4 prevented.

In Fig. 7c the cold strand 30 has already passed the rolling train 14 and the cooling section 16 and was cut off from the thin slab strand 3 by the scissors 17. In the illustrated state, the cold strand 30 was separated from the scissors 17 by driven rollers 33 and driver rollers.

According to Fig. 7d the cold strand 30 was stored by driven rollers 33 behind the drive rollers 18a of the winding device 18 on a roller table 12. In addition, the casting speed v _{C of} the continuous caster 1 has been increased and the thin slab strand 3 is reduced in thickness by the strand guide 4, whereby a wedge-shaped wedge piece 34 is formed. The unrolled thin slab strand 3 and the wedge piece 34 are chopped by the scissors 17 and the shredded material from the roller table 12 between the scissors 17 and the In addition, the rolling stands F1 to F4 of the rolling train 14 are now employed gradually to the thickness-reduced thin slab strand 3 and the thin slab strand 3 rolled into a hot strip 15. In the figure, the time is shown, in which the first rolling mill F1 is made to the thickness-reduced thin slab strand 3. The rolling stands F2 to F4 are still passed unrolled.

In Fig. 7e Finally, all rolling stands F1 ... F4 were employed, so that the thickness-reduced thin slab strand 3 is rolled into a hot strip 15 with a thickness between 2.5 and 10 mm. The hot strip 15 is cooled in the cooling section 16, then transversely split on bundle length or weight of the scissors 17 and wound up in the winding device 18 into coils.

In contrast to prior art cast-and-roller assemblies, the equipment of the invention is significantly simpler since it is e.g. only a single pair of scissors 17 needed and gets along completely without Entzunderer. In addition, the start-up of the cast-rolling composite plant is much easier. Nevertheless, the manufactured hot strip 15 is excellently suitable as a precursor for classic cold rolling.

While the invention has been further illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

LIST OF REFERENCE NUMBERS

1

continuous casting plant

2

ended mold

3, 3 '

Thin slab

4

strand guide

4a

vertical cut-off of the strand guide

4b

arcuate section of the strand guide

4c

horizontal section of the strand guide

5

liquid core

6

Strand guide segment

7

Extraction device

8th

pan

9

distribution trough

10

lifting device

11

scrap bucket

12

roller table

13

liftable lifting roller

14

rolling train

15

hot strip

16

cooling section

17

scissors

18

winding device

18a

driver rolls

19

nozzle

20

Control or regulating device

21, 21 '

Spray nozzle holder

22

linear actuator

30

dummy bar

31

Dummy bar head

32

link chain

33

driven roller

34

wedge

H

Thickness of the reduced thickness thin slab strand

F1 ... F4

rolling mill

D

specific throughput

R

radius

T

transport direction

v _C

casting speed

Claims (15)

A process for the continuous production of a coiled hot strip (15) of steel in a cast-rolling composite plant, wherein the cast-rolling composite plant - A continuous casting plant (1) for producing an endless thin slab strand (3, 3 '); - a rolling mill (14) having a plurality of rolling mills (F1 ... F4) for hot rolling the thin slab strand (3, 3 ') to the hot strip (15); - A cooling line (16) for cooling the hot strip (15); - A pair of scissors (17) for cutting the hot strip (15); and - A winding device (18) for winding the hot strip (15); comprises, comprising the steps: - Continuous casting of a molten steel in a continuous casting mold (2) of the continuous casting plant (1) to the thin slab strand (3, 3 '), wherein the thin slab strand (3, 3') at the exit from the continuous casting mold (2) has a liquid core (5), a Thickness of 45 to 70 mm, preferably 55 to 65 mm, and a width of 900 to 2300 mm, preferably 1100 to 1900 mm; - Supporting, guiding and reducing the thickness of the thin slab strand (3, 3 ') in a strand guide (4) of the continuous casting (1), wherein the reduced thickness thin slab strand (3, 3') has a thickness h of 35 to 52 mm, preferably 40 to 50 mm , a casting speed v _c and a specific flow rate D = hv _C of 0.45 m ² / min ≥ D ≥ 0.27 m ² / min ; Hot rolling of the endless, reduced thickness thin slab strand in the rolling train (14), wherein the thin slab strand is rolled out of its casting heat by at least three, preferably four, rolling passes to the hot strip (15) with a thickness of 2.5 to 10 mm and the final pass is made in the austenitic temperature range of the steel; - cooling the hot strip (15) in the cooling section (16); - cutting the cooled hot strip (15); and - winding the hot strip (15) into coils in the winding device (18). A method according to claim 1, characterized in that a control or regulating device (20) of the continuous casting plant (1) using a mathematical model - An actual position of a sump tip along the transport path of the thin slab strand (3, 3 ') in the strand guide (4) and - An actual temperature profile along the transport path of the thin slab strand (3, 3 ') in the strand guide (4) and in normal planes continuously calculated and the thin slab strand (3, 3') taking into account a desired position of the sump tip in the strand guide (4th ) Is cooled continuously, so that the actual position of the sump tip of the desired position corresponds as possible. Method according to one of the preceding claims, characterized in that the actual temperature T _{1Ist of} the hot strip (15) after the last rolling pass in the rolling train (14) and before cooling in the cooling section (16) is measured and the cooling of the thin slab strand ( 3, 3 ') in the strand guide (4) and / or the casting speed v _{c is} adjusted regulated, so that the actual temperature T _1Ist a setpoint temperature T _1Soll corresponds as possible. Method according to one of the preceding claims, characterized in that the thickness reduction applies a soft reduction in a region with still liquid core (5) or part-liquid core of the thin slab strand (3, 3 '). Method according to one of the preceding claims, characterized in that the actual temperature T _{2Ist of} the endless hot strip (15) after cooling in the cooling section (16) is measured and cooling nozzles of the cooling section (16) are controlled temperature controlled, so that the actual temperature T _{2Ist corresponds to} a target temperature T _2soll as possible. Method according to one of the preceding claims, characterized in that a federal government is then pickled and cold rolled by a plurality of rolling passes in a cold rolling mill to a thickness of 0.3 to 7 mm. Method for starting up a cast-rolling composite plant, wherein the cast-rolling composite plant - A continuous casting plant (1) for producing an endless thin slab strand (3, 3 '); - a rolling mill (14) having a plurality of rolling mills (F1 ... F4) for hot rolling the thin slab strand (3, 3 ') to the hot strip (15); - A cooling line (16) for cooling the hot strip (15); - A pair of scissors (17) for cutting the hot strip (15); and - A winding device (18) for winding the hot strip (15); comprises, comprising the steps: - casting the continuous casting plant (1), wherein a cold strand (30) which seals a continuous casting mold (2) of the continuous casting plant (1), in the transport direction (T) from the continuous casting mold (2) is pulled out; - Supporting and guiding the cold strand (30) subsequent thin slab strand (3, 3 ') in a strand guide (4) of the continuous casting; Passing the rolling stands (F1 ... F4) of the rolling train (14), wherein the cold train (30) passes through the rolling train (14) without being rolled; - Cutting the dummy strand (30) by the scissors (17); - Feeding the cold strand (30), wherein the cold strand (30) preferably the winding device (18) happens and in the transport direction (T) behind it is deposited; - dividing the non-rolled thin slab strand (3, 3 ') into a shredded material by the shears (17) and conveying out the shredded material; preferably increasing a casting speed v _c and reducing the thickness of the thin slab strand (3, 3 ') in the strand guide (4); - Setting the rolling stands (F1 ... F4) to the thin slab strand (3, 3 ') and hot rolling of the thin slab strand (3, 3') to a hot strip (15); - cooling the hot strip (15) in the cooling section (16); - cutting the cooled hot strip (15); and - winding the hot strip (15) into coils in the winding device (18). A method according to claim 7, characterized in that when increasing the casting speed, a specific flow rate D with D = hv _C of 0.45 m ² / min ≥ D ≥ 0.27 m ² / min is set. Cast-rolled composite plant for producing a coiled hot strip (15) made of steel, in particular for carrying out the method according to one of the preceding claims, comprising - A continuous casting plant (1), the - A continuous mold (2) for the continuous production of a thin slab strand (3, 3 '), a liquid core (5), a thickness of 45 to 70 mm, preferably 55 to 65 mm, and a width of 900 to 2300 mm, preferably 1100 to 1900 mm, when exiting the continuous casting mold (2); and - a strand guide (4) for supporting, guiding and reducing the thickness of the thin slab strand (3, 3 ') with a secondary cooling to cool the thin slab strand (3, 3'), wherein the thin slab strand (3, 3 ') after the thickness reduction, a thickness of 35 to 52 mm, preferably 40 to 50 mm, a casting speed v _C and a specific throughput D = hv _c of 0.45 m ² / min ≥ D ≥ 0.27 m ² / min ; includes; - A rolling train (14) for hot rolling the reduced thickness thin slab strand (3, 3 '), wherein the rolling train (14) at least three, preferably exactly four, rolling stands (F1 ... F4) and by hot rolling a hot strip (15) a thickness of 2.5 to 10 mm is generated; - A cooling line (16) for cooling the hot strip (15); - A pair of scissors (17) for cutting the cooled hot strip (15); and - A winding device (18) for winding the hot strip (15) to bonds. Cast-rolling composite plant according to claim 9, characterized in that the continuous casting plant (1) comprises a control or regulating device (20) and a mathematical model for continuous calculation - An actual position of a sump tip along the transport path of the thin slab strand (3, 3 ') in the strand guide (4) and - An actual temperature profile along the transport path of the thin slab strand (3, 3 ') in the strand guide (4) and in normal planes to comprising, wherein the control or regulating device (20) at least one controlled variable from the group of a cooling intensity in the secondary cooling and the casting speed v _c taking into account a desired position of a sump tip in the strand guide, so that the actual position of the sump tip of the thin slab strand (3, 3 ') of the desired position corresponds as possible. Cast-rolling composite plant according to claim 9 or 10, characterized in that an arcuate portion (4b) of the strand guide (4) has a radius of curvature R of 4.5 to 6.5 m, preferably 5 to 6 m. Cast-rolled composite plant according to one of claims 9 to 11, characterized in that in the region between the end of a horizontal section (4c) of the strand guide (4) and the first stand (F1) of the rolling train (14) heat insulation panels, preferably a thermal tunnel , are appropriate. Casting-rolling composite installation according to one of Claims 9 to 12, characterized in that the horizontal distance between two rolling stands (F1, F2, F3, F4) of the rolling train (14) is between 3 and 6 m, in particular between 4 and 5 m, is. Cast-rolling composite installation according to one of claims 9 to 13, characterized in that the length of the cooling section (16) is between 10 and 60 m. Casting-rolling system according to one of claims 9 to 14, characterized in that between the scissors (17) and a pair of drive rollers (18a) is arranged a lifting device (10), wherein the hot strip (15) by the drive rollers (18a ) and the hot strip (15) can be lifted by the lifting device (10), whereby the hot strip (15) of the scissors (17) can be pulled away.

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