EP2627465A1

EP2627465A1 - Energy- and yield-optimized method and plant for producing hot steel strip

Info

Publication number: EP2627465A1
Application number: EP11774009.2A
Authority: EP
Inventors: Gerald Hohenbichler; Josef Watzinger; Gerald Eckerstorfer
Original assignee: SIEMENS VAI METALS TECHNOLOGIES GmbH; Siemens VAI Metals Technologies GmbH Austria
Current assignee: Primetals Technologies Austria GmbH
Priority date: 2010-10-12
Filing date: 2011-10-10
Publication date: 2013-08-21
Anticipated expiration: 2031-10-10
Also published as: US20130186588A1; US9289807B2; KR20130109156A; RU2013120029A; CN103313812A; KR101809112B1; RU2579721C2; EP2441539A1; BR112013008875A2; WO2012049107A1; CN103313812B; EP2627465B1

Abstract

The invention relates to a method for continuously or semi-continuously producing hot steel strip which, starting from a slab (3) guided through a slab-guiding device (6), is rolled in a preferably at least four-stand roughing train (4) to form an intermediate strip (3') and, in a further sequence in a finish rolling train (5), into a final strip (3''). According to the invention, the thickness of a slab (3) cast in a die (2) is reduced in the liquid core reduction (LCR) process by means of the adjoining slab-guiding device to between 85 and 120 mm, preferably between 95 and 115 mm, a slab support length (L) measured between the meniscus (13), i.e., the bath level, of the die (2) and an end (14) of the slab-guiding device (6) facing the roughing train (4) being greater than or equal to 18.5 m, a casting speed (v_c) ranging from 3.8 to 7 m/min, and slabs (3) of different thicknesses (d) being cast as a function of given casting speeds. Using the casting parameters according to the invention, high-quality finishing is ensured with exceptionally high production capacities.

Description

description

Energy- and production-optimized process and plant for the production of steel heat-tape

Technical area

The invention relates to a process for the continuous or semi-continuous production of steel hot strip, which starting from a by a

Strand guiding device guided strand in one

Vorwalzstraße is rolled to an intermediate strip and subsequently in a finishing train to a final strip, according to claim 1 and a corresponding system for

Implementation of this method according to claim 22.

One speaks of continuous production or

"Continuous rolling", when a casting plant is so connected to a rolling mill, that the strand cast in a mold of the casting plant directly - without separation from the straight

Cast strand part and without intermediate storage - led to a rolling mill and there to a desired

Final thickness is rolled. The beginning of the strand can therefore already be finished rolled to a steel strip to the final thickness, while the casting plant continues to pour on the same strand, so there is no end of the strand exists. One speaks also of directly coupled operation or endless operation of the casting and rolling plant.

In the semicontinuous production or "semi-continuous rolling" the cast strands are divided after casting and the divided strands or slabs without

Intermediate storage and cooling supplied to ambient temperature of the rolling mill. The strand emerging from the mold of the casting plant

first goes through one directly to the mold

subsequent strand guide device. The as well

"Strand guiding corset" means strand guiding device comprising several (usually three to six)

Guide segments, each guide segment comprises one or more (usually three to ten) pairs of preferably designed as a strand support rollers guide elements. The support rollers are rotatable about an axis orthogonal to the transport direction of the strand.

Instead of strand support rollers, individual

Guide elements also as static, e.g. skid-shaped

Be executed components.

Regardless of the specific design of the guide elements, these are arranged on both sides of the strand broad sides, so that the strand is guided by upper and lower Führungselemente- series and transported to a roughing mill.

Exactly seen, the strand is not only by the

Strand guiding device supported, but also by a lower end portion of the mold, which is why you could view the mold as part of the strand guide device.

The Strangerstarrung begins at the top of the

(Continuous) kokille at the bath level, at the so-called "meniscus", wherein the mold is typically about Im long (0.3 - 1, 5m).

The strand exits vertically downward from the mold and is deflected into the horizontal. The

Strand guiding device therefore has a substantially curved over an angular range of 90 ° course. The emerging from the strand guide device strand is in the roughing mill (HRM, High-Reduction Mill)

reduced thickness, the resulting intermediate band is heated by a heater and in a

Finish rolling mill finished rolled. In the finishing train is hot rolled, that is, the rolling stock has a temperature above its recrystallization temperature during rolling. For steel this is the range above about 750 ° C, usually is rolled at temperatures up to 1200 ° C warm.

When hot rolling steel, the metal is usually in the austenitic state, where the iron atoms are cubic

are arranged surface centered. One then speaks of rolls in the austenitic state, when both the initial and the final rolling temperature are in the austenitic region of the respective steel. The austenite area of a steel depends on the steel composition, but is usually above 800 ° C.

Relevant parameters in the manufacturing process of

Steel hot strip made of cast-rolled composite plants are the

Casting rate at which the strand leaves the mold (and passes through the strand guide device) and the mass flow rate, which is indicated as the product of the casting speed with the thickness of the strand and usually carries the unit [mm * m / min]. The produced steel bands are used for

Motor vehicles, household appliances and construction

further processed.

State of the art

From the prior art is the continuous and

Semicontinuous production of steel hot tapes already known. Due to the coupling of caster and rolling mill the mastery of all plant parameters represents a high technical process requirement. Modifications in the casting and rolling process, in particular by changing the

Casting speed in combination with the strand thickness and a material-specific and a cooling

controllable solidification coefficients have a

considerable impact on the quality of the production and

Energy efficiency of the plant.

Generic methods or systems are known e.g. from EP 0 415 987 B1, EP 1 469 954 Bl and DE 10 2007 058 709 AI and WO 2007/086088 AI known.

Significant progress has been made in hot rolling technology

especially from the Acciaieria Arvedi S.p.A. which is based on an ISP technology (in-line strip production) based thin slab continuous process under the name

Arvedi ESP (Endless Strip Production).

In this ESP process, the casting and rolling processes are combined with each other in a particularly advantageous manner, so that subsequent cold-rolling is possible for many

Stahlwarmbandgüten is no longer necessary. With such steel heat-tape grades, in which subsequent cold-rolling is still required, the number of rolling stands can be reduced compared to conventional rolling mills.

A e.g. in the Rolling & Processing Conference '08

(September) and published in Cremona, Italy

Arvedi's ESP plant for steel hot strip production comprises a pre-rolling mill following a continuous casting plant with three roughing stands, two strip separating devices and an induction furnace for the production of

Intermediate heating of the pre-rolled intermediate strip, followed by a finishing train with five finishing stands. The emerging from the roughing final band is in a

Cooling section cooled and by means of three underfloor reels to tape rolls with a weight of up to 32 tons

wound. The underfloor reel is a

Separator upstream in the form of a high-speed shear. Depending on the steel grades and the strength of the rolled steel strip, the production capacity of these is

single-strand production line at about 2 million tons per year (mtpy). This publication is also described in the following publications: "Arvedi ESP - technology and plant design", Millenium Steel 2010, March 1, 2010, pages 82-88, London, and Siegl et al: "Arvedi ESP - First Tin Slab Endless Casting and Rolling Results ", 5th European Rolling Conference, London, June 23, 2009. One particular drawback is one that is too short

Strand support length of 17 m, that is more accurate than

"Metallurgical length" refers to the distance between the pouring area of the mold, specifically between the liquid level of the liquid steel, referred to as the "meniscus", and the end of the mold facing the roughing line

Strand guiding device.

As already described above, forms the

Strand guiding device between the guide elements or the strand support rollers a partially curved

Receiving shaft for receiving the freshly cast (still having a liquid core) strand out.

As the end of the strand guide device is thus in

present connection to the strand contacting

intended guiding surface or surface line of the last of the pre-rolling facing guide element or the last support roller of the upper guide elements series understood. With increasing distance from the meniscus guided in the strand guiding device strand or located in its original form steel strip cools more and more. That inner portion of the strand, which is still liquid or of doughy swampy consistency, is referred to as

Liquid sump called. A kokillenfernere "Sumpfspitze" of the liquid sump is as the centric

Defined cross-sectional area of the strand, in which the temperature is just about the steel solidus temperature and then drops below this. The temperature of the sump tip therefore corresponds to the solidus temperature of the respective steel grade (typically between 1300 ° C and 1535 ° C.

The rolling of a completely solidified or cooler

Cast strand requires a much higher

Energy expenditure as the rolling of a cast strand with hot cross-sectional core.

For volume flows below 380-400 mm * m / min, so far only a discontinuous production ("batch operation") has taken place in the ISP or ESP process.

CSP known from the prior art (Compact Strip

Production) processes work with strand thicknesses of 45-65 mm also with volume flows below approx. 400 mm * m / min using a roller hearth furnace with a length of

250 m and more, whereby only batch production or semicontinuous production takes place, in which case 3-6 separated strands or slabs (no longer connected to the casting machine or mold) are endlessly rolled EP 0 889 762 Bl is for continuous casting and rolling of hot strip a volumetric flow> 0.487 mm ² / min (converted to the usual unit mentioned at the beginning:> 487

mm * m / min). A casting with such a high

Volume flow at a relatively low strand thickness, however, proves to be too fast for many types of steel in order to be able to ensure sufficient production quality.

Presentation of the invention

In the course of increasing cost and production pressure, the aim is to increase the capacity of the plant while further optimizing the production of steel hot-rolled strip for a variety of steel grades, cooling parameters and strand thicknesses.

The energy efficiency of generic systems for

Production of steel hot-rolled strip is to be increased and thereby a more economical production is made possible. To the casting heat during the manufacturing process of

To optimally utilize hot strip steel, it should be ensured that the sump tip, ie the just doughy ^¬ liquid cross-sectional ^{core of} the in the

Strand guiding device transported strand always as far away as possible from the mold and as close to the end of the strand guide device and thus as close to

Entrance is located in the roughing mill.

In this task, it should be noted that in

Dependence of a material-specific solidification factor and a respectively set strand thickness

Casting speed or the volume flow passing through the strand guiding device must also not be too large, since in such a case a shifting out of the sump tip beyond the strand guiding device and thus an inflation and bulging of the strand or the steel hot strip to

could take place. The above objects are achieved by a method having the features of claim 1 and a system having the features of claim 19.

A process for the continuous or semi-continuous production of steel hot strip, which is rolled starting from a guided through a strand guide strand in a roughing train to an intermediate strip and subsequently in a finishing train to an end belt according to the invention is characterized in that cast in a casting line strand a Strand thickness between 105 and 130 mm, preferably a strand thickness between 115 and 125 mm, and in liquid core reduction (LCR)

Method by means of the subsequent

Strand guiding device is reduced to a thickness between 85 and 120 mm, preferably to a thickness between 95 and 115 mm, with a liquid between the meniscus, d.i. the pouring mirror of the

Casting plant and one of the Vorwalzstraße facing the end of the strand guide device measured strand support length is greater than or equal to 18.5 m, preferably in a range between 18.7 and 23 m, more preferably between 20.1 and 23 m, and wherein a casting speed v _c in a range of 3.8 - 7 m / min. The strands are cast with different strand thicknesses depending on the following casting speeds:

at casting speeds between 3.8 and 5.0 m / min with a strand thickness of 100-120 mm, preferably with a strand thickness of 110-120 mm,

- At casting speeds between 5, 0 and 5, 9 m / min with 85 - 110 mm strand thickness, preferably 95 to 110 mm

Strand thickness,

- at casting speeds greater than or equal to 5, 9 m / min with a maximum of 102 mm strand thickness. By using these pouring parameters according to the invention, on the one hand, a high production quality is ensured by the bottom tip of the strand being independent of the respective one

Materialgüteabhängigen maximum casting speeds always comes close to the end of the strand guide device, on the other hand, an extremely high

Production capacity achieved.

The steel strip has a sufficiently hot cross-sectional core during its reduction in thickness in the downstream of the strand guide device Vorwalzstraße to be rolled with relatively little energy.

The energy consumption when rolling steel heat band is thus significantly reduced and the efficiency of generic

Systems increased. Calculations have shown that when using

Casting parameters according to the invention for strands between 1400 and 1850 mm width have a production capacity of more than 3

Million tons per year (mtpy) are possible, which is a great increase over prior art systems and methods, and a much more economical one

Production of steel hot-rolled allows, but without

Risk quality loss. By means of a

Process according to the invention are also steel grades

processable, which is for a continuous or endless manufacturing process lt. prevailing to date

Expert opinion do not have suitable.

In order to further optimize the method according to the invention, special process parameters were determined by calculations and experimental arrangements, which with regard to

Production quality and energy efficiency a profitable

Enable progress in the production of steel warming strap. According to the invention, it is provided that strands having different strand thicknesses are cast in dependence on the following casting speeds:

- At casting speeds between 3.8 and 5.0 m / min with 100-120 mm strand thickness, preferably with 110 to 120 mm

Strand thickness,

- At casting speeds between 5, 0 and 5, 9 m / min with 85

- 110 mm strand thickness, preferably 95 to 110 mm

Strand thickness,

- at casting speeds greater than or equal to 5, 9 m / min with a maximum of 102 mm strand thickness.

By setting such strand thicknesses as a function of respective (steel-specific) maximum

Casting speeds will ensure that the

Swamp tip of the strand - with the exception of Angießphase - always held reasonably close to the end of the strand guide device and thereby the casting heat can be optimally utilized to increase the efficiency of subsequent rolling processes.

According to a further preferred embodiment of the invention, it is provided that in the roughing line, a rough rolling of the strand into an intermediate strip in at least four rolling passes, i. using four

Pre-rolling stands, preferably in five rolling passes, i. carried out using five roughing stands. While in processes according to the prior art usually a rough rolling of the strand is carried out in three rolling passes, the energy efficiency of the rolling process can be further increased by an inventive four or five rolling passes. By making four or five rolling passes in

be carried out as quickly as possible sequence, the casting heat still in the strand is optimally utilized. Of

Further, when four or five rolling passes are made, a very narrow thickness range of the intermediate strip (between 3 and 15 mm, preferably between 4 and 10 mm) is achieved, so that a downstream of the roughing mill heater, such as a cross-field inductive heating furnace, designed exactly to a specific thickness range of the intermediate band can be. Energy losses due to a too large

Dimensioning of the recording of the heater can thus be avoided.

According to a further preferred embodiment variant of the invention, it is provided that the four or five rolling passes taking place in the rough rolling mill take place within a maximum of 80 seconds, preferably within a maximum of 5 seconds.

According to a further preferred embodiment of the invention, it is provided that the first rolling pass in the roughing mill within a maximum of 7 minutes, preferably within not more than 6.2 minutes from beginning of solidification of the liquid strand steel in the casting plant

he follows. Ideally, the first pass in the roughing mill takes place within a maximum of 5, 8 minutes, even at casting speeds in the region of 4 m / min.

According to a further preferred embodiment of the invention, it is provided that between the end of

Strand guiding device and an inlet region of the

Vorwalzstraße only one conditional by the ambient conditions in the form of natural convection and radiation

Cooling of the strand is allowed, i. none

artificial cooling of the strand by means of a

Cooling device is done. According to a further preferred embodiment variant of the invention, it is provided that a reduction of the thickness of the strand by 35-60%, preferably by 40-55% takes place in the roughing mill per rolling pass. With a providence of exactly four rolling stands, it follows that a

Intermediate band with a thickness of about 3 to 15 mm,

preferably with a thickness of 4 to 10 mm from the

Vorwalzstraße 4 expires.

According to a further preferred embodiment variant of the invention, it is provided that a temperature loss rate of the intermediate strip emerging from the rough rolling mill is below a maximum of 3 K / m, preferably below a maximum of 2.5 K / m. It would also be conceivable to realize temperature loss rates <2 K / m. Such

Temperature loss rate is due to heat radiation and / or convection from the intermediate band and can be controlled by an appropriate choice of thermal boundary conditions (covers, tunnels, cold air, humidity, ...) and transport speed or mass flow.

According to a further preferred embodiment of the invention, it is provided that a heating of the leaked out of the roughing intermediate belt by means of an inductive heating device, preferably in

Querfeldwärmungsverfahren, starting at a temperature above 770 ° C, preferably above 820 ° C to a temperature of at least 1110 ° C, preferably to a

Temperature above 1170 ° C takes place.

According to a further preferred embodiment of the invention, it is provided that the heating of the

Zwischenbandes within a period of 4 to 25

Seconds, preferably within a period of 5 to 13 seconds. According to a further preferred embodiment variant of the invention, it is provided that when exactly four rolling passes are made in the rough rolling mill, the time interval between the first pass and the inlet to the heating device does not exceed 105 seconds for intermediate strip thicknesses of 5-10 mm, preferably not longer than 70 seconds.

Adherence to these parameters results in a very

compact system in which the distance of the heater to the casting plant or Vorwalzstraße is kept very low, which allows a thermal efficiency advantage.

According to a further preferred embodiment of the invention, it is provided that a finish rolling of the heated intermediate strip in the finishing train in four rolling passes, i. using four finishing stands or in five rolling passes, i. using five

Fertigwalzgerüsten to an end strip with a thickness <1.5 mm, preferably <1.2 mm. By means of a

inventive method is also a rolling on

End thicknesses of <1 mm possible.

According to a further preferred embodiment of the invention, it is provided that the within the

Rolling mill carried out by the five or four finishing mills rolled within a maximum period of 16 seconds, preferably within a maximum period of 8 seconds.

According to a further preferred embodiment variant of the invention are for liquid core reduction

(LCR) thickness reduction of the strand to the contacting of predetermined guide elements of the strand guiding device relative to a longitudinal axis of the strand (transversely) adjustable, wherein an adjustment of the guide elements is made depending on the material of the strand and / or the casting speed in order to reduce the strand thickness by up to 30 mm.

According to one embodiment of the invention, it is provided here that the strand thickness quasi-static, i. shortly after the start of casting or the casting of a casting sequence, as soon as the "front of the head" called, warm

Strand area intended for reducing the thickness

Guiding elements has happened, is set once.

In a particularly preferred embodiment, however, provision may also be made for the strand thickness to be dynamically adjustable, i. is arbitrarily variable during the casting process or during the passage of the strand through the strand guiding device. The dynamic setting is then preferably set by the operating team depending on the steel grade and the actual casting speed, if this changes only on a case-by-case basis. The LCR

Thickness reduction is between 0 and 30 mm, preferably between 3 and 20 mm.

In a preferred embodiment of the dynamic

Application of LCR can also do this function from one

be taken over automated setting, especially if very frequent thickness or

Speed changes would be common or required.

The connection between the setting of the strand thickness in

Connection with the casting speed takes place by means of inventively proposed speed factors K, the selection of which takes place as a function of the strand support length and the quality of the extruded steel. For the speed factor K are respectively

Corridor areas indicated, within which a

casting technology operation is efficient and feasible feasible. The cooling characteristic of respective steel grades has a great influence on the position of the sump tip within the strand. Fast solidifying steel grades allow one

Operation of the system with relatively high casting speeds v _c , while for slower hardening steel grades lower casting speeds v _{c are} to be selected in order to prevent bulging and bursting of the strand in the area of the swamp tip. In connection with the speed of cooling the strand is called "hard cooling" (fast

Solidification), "medium-hard cooling" and "soft cooling" (rather slow solidification).

To cool the strand is on these in the field of

Strand guiding device (between the end of the mold and the Vorwalzstraße facing the end of the

Strand guiding device) a coolant, preferably

Water, upset. The application of the coolant to the strand takes place by means of an injection device, which can comprise any desired number of spray nozzles.

For a hard cooling 3 to 4 liters of coolant per kg of extruded steel are used, while for a medium-hard cooling 2 to 3.5 liters of coolant per kg of extruded steel and for a soft cooling <2.2 liters of coolant per kg extruded steel are used. The quoted amounts of coolant for hard, medium-hard and soft cooling overlap, since the realization of a hard, medium-hard or soft cooling in practice not only on the amount of coolant, but also by the structural design of the

Spraying device, in particular the Düsenaufbauart (es exist pure water nozzles and air / water nozzles, so-called "2-phase nozzles")

Speed of strand cooling are the design of the

Guide elements or strand support rollers of

Strand guiding device (inside or jacket-cooled

Strand support rollers), the arrangement of the support rollers,

In particular, the ratio of the support roller diameter to the distance between adjacent support rollers, the spray character of the nozzles and the coolant or water temperature. Within the invention proposed

Corridor areas is the choice of a concrete

Speed factor K in particular as a function of the steel grade or the cooling characteristic of the strand. For steel grades to be cooled rapidly, a speed factor K lying in the upper region of a corridor region proposed according to the invention can be used, while for slower-to-cool steel grades a velocity factor K lying in the middle or lower region of a corridor region proposed according to the invention

is used.

Thus, it is provided according to a process engineering optimization that by means of a spraying device in

Area of the strand guide device to be cooled hard

Strand steels, i. with application of 3 to 4 liters

Coolant per kg extruded steel, in a stationary continuous operation of the plant, the relationship between a strand thickness d measured in [mm] and the casting speed v _c measured in [m / min] according to the formula v _c = K / d ²

is complied with, with one included in the formula

Speed factor K at a strand support length L = 17.5 m in a corridor range of 42000 to 48900, preferably in a corridor range of 45500 to 48900, while the Speed factor K at a strand support length L = 23 m in a corridor range of 55200 to 64600, preferably in a corridor range from 59900 to 64600, wherein for determining (target) casting speeds v _c or

(Target) strand thickness d for plants with between the

Strand support lengths L = 17.5 m and L = 23 m

Strand support lengths L an interpolation between the

previously mentioned corridor areas is feasible.

Under a stationary-continuous operation of the system are understood in the present context operating phases with a duration of> 10 minutes, during which the

Casting speed is substantially constant. The

On the one hand, the definition of steady-state plant operation merely serves to delimit against a start-up phase during which the molten steel initially passes through the strand guiding device and during which the casting speed is subject to extraordinary parameters or, on the other hand, also acceleration phases which are possible in the meantime to increase throughput and / or operationally required deceleration phases (if you have to wait for the delivery of liquid steel or because of strand quality, lack of cooling water, ...).

For moderately hard to be cooled strand steels, i. under

Application of 2 to 3.5 liters of coolant per kg

Extruded steel, in a steady-state continuous operation of the plant, the relationship of one measured in [mm]

Strand thickness d with that measured in [m / min]

Casting speed v _c according to the formula v _c = K / d ²

complied with, one included in the formula

Speed factor K at a strand support length L of 17.5 m in a corridor range from 39600 to 46500, preferably in a corridor range from 43050 to 46500 while the speed factor K is at a

Strand support length L = 23 m in a corridor range of 52100 to 61900, preferably in a corridor range of 57000 to 61900, wherein for determining

(Target) casting speeds v _c or (target) strand thicknesses d for installations with strand support lengths L between the strand support lengths L = 17.5 m and L = 23 m, an interpolation between the corridor regions mentioned above can be carried out. For soft-to-cool extruded steels, ie, applying less than 2.2 liters (preferably between 1.0 and 2.2 liters) of coolant per kg of extruded steel, is in one

stationary-continuous operation of the plant

The relationship of a strand thickness (d) measured in [mm] with the casting speed v _c measured in [m / min] according to the formula v _c = K / d ² , where a velocity factor K contained in the formula has a strand support length L of 17, 5 m in a corridor area from 37100 to 44100,

preferably in a corridor range from 40600 to 44100, while the speed factor K at a

Strand support length L = 23 m in a corridor range of 48900 to 59000, preferably in a corridor range of 53950 to 59000, wherein for determining

(Target) casting speeds v _c or (target) strand thicknesses d for installations with strand support lengths L between the strand support lengths L = 17.5 m and L = 23 m, an interpolation between the corridor regions mentioned above can be carried out.

The detailed / refined choice of the speed factor is in addition to the strand support length in particular from

Carbon content of the cast steels whose solidification or conversion characteristics whose strength or

Ductility properties etc. dependent.

An operational management according to the invention

proposed speed factors K allows optimal utilization of the casting heat contained in the strand for the subsequent rolling process and an optimization of the material throughput and thus a productivity advantage (with operational decrease of the casting speed, the strand thickness can be increased and thereby the material throughput can be increased).

Claim 19 is directed to a system for carrying out the method according to the invention for the continuous or semi-continuous production of steel hot strip, comprising a casting machine with a mold, a downstream of this strand guide device, one of these downstream

Pre-rolling mill, one of these downstream, inductive

Heating device and one of these subordinate

A finishing train, wherein the strand guiding device comprises a lower series of guide elements and a parallel or converging arranged upper series of guide elements and between the two guide elements series for receiving the strand emerging from the casting strand provided receiving shaft is formed, which by forming different distances opposite guide elements is tapered to each other at least in sections in the transport direction of the strand and thereby the strand is Dickenreduzierbar. According to the invention, it is provided that the clear receiving width of the receiving shaft at its inlet area facing the mold is between 105 and 130 mm, preferably between 115 and 125 mm

Receiving shaft at its forward of the roughing end facing one of the strand thickness of the strand corresponding clear Receiving width between 85 and 120 mm, preferably between 95 and 115 mm, wherein a between the casting level of the caster and the Vorwalzstraße facing the end of the receiving shaft of the strand guide device measured strand support length is greater than or equal to 18.5 m,

Preferably, in a range between 18.7 and 23 m, more preferably between 20.1 and 23 m, and wherein a control device is provided, by means of which the casting speed v _{c of} the strand 3 in a range between 3.8 - 7 m / min is durable.

According to a preferred embodiment of the

Plant according to the invention it is provided that the

Pre-rolling mill comprises four or five roughing stands.

According to a further preferred embodiment of the system according to the invention, it is provided that between the end of the receiving shaft or the strand guiding device and an inlet region of the roughing train no

Cooling device, however, a thermal cover is provided which surrounds a transport device provided for transporting the strand at least in sections, and thus delays cooling of the strand.

According to a further preferred embodiment variant of the system according to the invention, it is provided that by means of pre-rolling stands a reduction of the thickness of the strand by 35-60%, preferably by 40-55% per roughing mill feasible, so that an intermediate band with a thickness from 3 to 15 mm,

preferably with a thickness of 4 to 10 mm can be generated.

According to a further preferred embodiment

Plant according to the invention it is provided that the

Heating device as inductive transverse field heating furnace is formed, by means of which the strand, starting at a temperature above 770 ° C, preferably above 820 ° C to a temperature of at least 1110 ° C,

preferably can be heated to a temperature of above 1170 ° C.

According to a further preferred embodiment of the system according to the invention, it is provided that the

Prefabricated rolling mill comprises four or five finishing mills, by means of which emerging from the roughing mill

Intermediate band can be reduced to an end band with a thickness of <1.5 mm, preferably <1.2 mm.

Finishing mills at intervals of <7 m,

are preferably arranged at intervals of <5 m to each other, wherein the distances between the work roll axes of the finishing mills are measured.

Thickness reduction of the strand certain guide elements (gap) are adjustable and thus a light

Recording width of the receiving shaft is reduced or

is enlargeable, wherein the strand thickness or the light

Recording width is adjustable depending on the material of the strand and / or the casting speed.

adjustable guide elements in one of the mold

facing front half, preferably in one of

Mold facing front quarter of the longitudinal extent of the strand guide device are arranged. At least during the first two rolling passes the

To ensure the presence of a strand core of the strand which is as hot as possible, it is according to a preferred

Embodiment variant of the system according to the invention provided that a work roll axis of the

Strand guiding device next adjacent first

Vorwalzgerüstes the roughing mill is arranged a maximum of 7 m, preferably a maximum of 5 m after the end of the strand guiding device.

According to a further preferred embodiment of the system according to the invention, it is provided that an inlet end facing the pre-rolling line

Heating device maximum 25 m, preferably not more than 19 m after the work roll axis of the heater

nearest roughing stand is arranged.

BRIEF DESCRIPTION OF THE FIGURES

The invention will now be explained in more detail with reference to an embodiment. Showing:

Fig.l is a schematic representation of an inventive system for continuous or semi-continuous production of steel hot strip in side view

2 shows a detailed representation of a strand guiding device of the system from FIG. 1 in a vertical sectional view

3 shows a section of the strand guiding device in a sectional detail view

4 shows a process diagram of an inventive

Manufacturing process (casting speed / strand thickness)

5 is a diagram for illustrating the

Annual throughput of a plant according to the invention in Dependence of the strand thickness (casting speed /

Strand thickness)

Fig. 6 is a process diagram of an inventive

Manufacturing process (context of target

Casting speeds and target strand thicknesses)

Embodiment of the invention

Fig.l shows schematically a plant 1, by means of which a method according to the invention for the continuous or semi-continuous production of steel hot strip is feasible.

One can see a vertical casting machine with one

Mold 2, are cast in the strands 3, which is a

Strand thickness d between 105 and 130 mm, preferably one

Strand thickness d between 115 and 125 mm at the end of the mold 2 have.

The mold 2 is preceded by a pan 35, which feeds a distributor 36 with liquid steel via a ceramic inlet nozzle. The distributor 36 subsequently charges the mold 2, to which a strand guiding device 6 adjoins.

Then the rough rolling takes place in a rough rolling 4, which may consist of a - as here - or of several scaffolds and in which the strand 3 is rolled to an intermediate thickness. During roughing, the transformation of cast structures into fine-grained rolling structures takes place.

The system 1 further comprises a number of components not shown in FIG.

Entzunderungseinrichtungen 37,38 and Fig.l not

shown separating devices, which essentially correspond to the prior art and therefore on this Place not discussed. The severing devices, for example in the form of high-speed shears, can be arranged at any position of the plant 1, in particular between the rough rolling mill 4 and the finishing train 5 and / or in a downstream region of the finishing train 5.

Behind the rough rolling 4 a heating device 7 for the intermediate band 3 ^'is arranged. The heater 7 is designed in the present embodiment as an induction furnace. Preferably, a transverse field heating induction furnace is used, which the plant 1 particularly

makes energy efficient.

Alternatively, the heater 7 could also as

conventional oven e.g. with flame exposure

be executed.

In the heater 7, the intermediate band 3 ^'is relatively uniform over the cross section to a desired

Inlet temperature for the inlet brought into the finishing train 5, wherein the inlet temperature usually depending on the steel grade and subsequent rolling in the

Finishing mill 5 is between 1000 ° C and 1200 ° C.

After the heating in the heating device 7 takes place - after an interposed optional descaling -the

Fertigwalzung in multi-stand finishing train 5 to a desired final thickness and final rolling temperature and

then a belt cooling in a cooling section 18 and ultimately a winding to frets by means of underfloor reel 19th

According to the invention, the following method steps

carried out: First of all, a strand 3 is used with a casting plant 2 (in FIGS. 1-3, a mold of the casting plant is shown)

cast. Strand 3 is added in the liquid core reduction (LCR) process by means of strand guiding device 6

liquid cross-sectional core to a strand thickness d between 85 and 120 mm, preferably reduced to a strand thickness between 95 and 115 mm.

One between the meniscus 13, d.i. the pouring mirror of the

Caster 2 and one of the roughing train 4 facing the end 14 of the strand guide device 6 measured strand support length L is greater than or equal to 18.5 m, preferably is the

Strand support length L in a range between 18.7 (even better 20.1) and 23 m. A measured during stationary continuous operation of the plant

Casting speed v _{c of} the strand 3 is in this case in a range of 3.8 - 7 m / min.

The meniscus 13, which can be seen in detail in FIG. 3, is located i.d.R. a few centimeters below the upper edge 34 of the mold 2 usually made of copper. The strand support length L is in this case between the meniscus 13 of the mold or the casting plant 2 and the axis of the last, a Vorwalzstraße 4 facing role one and below in more detail described upper Führungselemente- Series 10 measured (considered in a side view of the Appendix 1 in parallel to the axes of the rollers viewing direction according to Fig.l). With exact measurement, the strand support length L is at a

relative to the center of the radius of curvature of the strand 3 or the strand guiding device 6 outer broad side of the strand 3 and the strand guiding device 6 (and a portion of the interior of the mold 2) measured. For better recognizability of the tangled by support rollers 10 outer

Broad side of the strand 3 or the strand support length L is in 2 a concentric to the strand support length L.

Auxiliary dimension line L 'drawn in.

To ensure that an initially defined

Swamp tip of strand 3 regardless of respective

material quality dependent maximum casting speeds always close to the end of the strand guiding device 6

approaches and thus the strand 3 with relatively little energy and ensuring high

Production quality to a desired intermediate thickness before and subsequently can also be finish-rolled, be

Strands 3 with different strand thicknesses d in

Cast depending on the following casting speeds:

- At casting speeds between 5, 0 and 5, 9 m / min with 85

- 110 mm strand thickness, preferably 95 to 110 mm

Strand thickness,

In the roughing mill 4, a rough rolling of the strand 3 to an intermediate strip 3 'takes place in at least four rolling passes, ie using four roughing stands 4i, 4 ₂ , 4 ₃ , 4 ₄ ,

preferably in five rolling passes, ie using five roughing stands 4i, 4 ₂ , ^ 3, 4 ₄ , 4s takes place.

The taking place in the roughing mill 4 four or five

Rolling passes take place within a maximum of 80 seconds, preferably within a maximum of 5 seconds.

Furthermore, it is provided that the first rolling pass of the roughing train 4 within a maximum of 7 minutes, preferably within a maximum of 6.2 minutes from Start of solidification of located in the caster 2 liquid extruded steel takes place. Ideally, the first rolling pass takes place in the roughing mill 4 within

5.8 minutes at the maximum, even at casting speeds in the range of 4 m / min.

Between the end 14 of the strand guide device 6 and an inlet region of the roughing train 4 is only caused by an ambient temperature cooling of

Stranges 3 admitted, i. there is no artificial cooling of the strand 3 by means of a cooling device. The surface of the strand 3 has in this area on average a temperature> 1050 ° C, preferably> 1000 ° C on.

Between the end 14 of the strand guide device 6 and the first roughing stand 4i, a preferably hinged thermal cover is provided in order to keep the heat as possible in the strand 3. The thermal cover surrounds one intended for the transport of the strand 3, usually as

Roller conveyor running at least

sections. Immediately before the underfloor reels 19, the end band 3 '' clamped between drive rollers 38, which also lead the end band '' and hold under strip tension.

In this case, the thermal cover can surround the conveying device from above and / or from below and / or laterally.

In the roughing mill 4 per roll pass, a reduction of the thickness of the strand 3 by 35-60%, preferably by 40-55%. With a provision of exactly four roll stands, it follows that an intermediate strip 3 'with a thickness of 3 to 15 mm, preferably with a thickness of 4 to 10 mm, leaves the rough rolling line 4.

At least during the first two rolling passes the

Presence of the highest possible strand core of the To ensure Stranges 3, that is to

Strand guiding device 6 next to the first

Pre-rolling stand 4i the roughing mill maximum 6 m, preferably a maximum of 5, ideally not more than 4 m after the end 14 of the strand guiding device 6 is arranged. The mentioned

Distances are in each case from the center of the first roughing stand 4 ₁ or from the work roll axis

measured.

According to another preferred procedural variant, it is provided that a cooling of the from

Pre-rolling 4 exiting intermediate belt 3 'under a cooling rate of a maximum of 3 K / m, preferably below a

Cooling rate of a maximum of 2.5 K / m takes place. Such

Cooling rate is due to heat radiation and / or - convection of the intermediate band and is by an appropriate choice of thermal boundary conditions (covers, tunnels, cold air, humidity, etc.) and

Transport speed or mass flow controllable.

According to a preferred embodiment of the invention, it is provided that a heating of the from

Vorwalzstraße 4 leaked intermediate band 3 'by means of an inductive heating device 7, preferably in

Transverse field heating method, starting at a temperature above 770 ° C, preferably above 820 ° C,

particularly preferably: above 950 ° C., to a temperature of at least 1110 ° C., preferably to a temperature of above 1170 ° C.

The heating of the intermediate strip 3 'takes place within a period of 4 to 25 seconds, preferably within a period of 5 to 13 seconds. By making exactly four rolling passes in the

Vorwalzstraße 4, it is provided that a when exiting the casting plant 2 or when entering the

Strand guiding device 6 100 mm thick strand 3, which in the roughing mill 4 to an intermediate band 3 'with a

Thickness of 7 mm is reduced after 360 seconds at the latest, preferably after 340 seconds at the latest from the casting plant 2 in the inductive heating device. 7

is introduced and that when leaving the

Caster 2 or when entering the

Strand guiding device 6 115 mm thick strand 3, which is reduced in the roughing mill 4 to an intermediate band 3 'with a thickness of 7.8 mm, at the latest after 480

Seconds, preferably after 460 seconds at the latest

Exit from the casting plant 2 in the inductive

Heating device 7 is introduced.

A finish rolling of the heated intermediate strip 3 'in the

Prefabricated rolling train 5 is preferably carried out in four rolling passes, ie using four finishing stands 5i, 5 ₂ , 5 ₃ , 5 ₄ or in five rolling passes, ie using five

Precast rolling stands 5i, 5 ₂ , 5 ₃ , 5 ₄ , 5s to an end strip 3 '' with a thickness of <1.5 mm, preferably <1.2 mm. By means of a method according to the invention is also a rolling

End thicknesses of <1 mm possible. The finishing mills 5i, 5 ₂ , 53, 5 ₄ , 5s are each under

Distances of <7 m, preferably arranged at intervals of <5 m to each other (measured between the

Work roll axes of the finishing stands 5i, 5 ₂ , 53, 5 ₄ , 5s).

As a result, the end band 3 '' on a

Reel temperature between 500 ° C and 750 ° C, preferably cooled to 550 ° C and 650 ° C and coiled into a bundle.

Finally, a transection of the end band 3 'or of the intermediate band 3 'or of the strand 3 in a direction transverse to the direction of transport 15 and a ready direction of the rolling mill side loose end band 3'.

Alternatively to rewinding would also be a diversion and

Stacking of the end band 3 '' possible.

As can be seen in FIG

Strand guiding device 6 more for the passage of the

Stranges 3 predetermined guide segments 16 as shown in FIG. 3, each of a (not shown in Figure 3 Ilten) lower series of guide elements 9 and a parallel or converging arranged upper series to

Guide elements 10 are constituted.

Each guide element of the lower guide element series 9 is an opposite guide element of the upper

Guide elements series 10 assigned. The guide elements are thus arranged in pairs on both sides of the broad sides of the strand 3.

Between the two guide elements series 9, 10 a receiving shaft 11 provided for receiving a strand 2 emerging from the casting installation 2 is formed, which is at least partially tapered by forming different distances between opposing guide elements 9, 10 in the transport direction of the strand 3 and thereby the strand 3 thickness reducible. The guide elements 9, 10 are designed as rotatably mounted rollers.

As can be seen in FIG. 2, the upper and lower guide element or roller series 9, 10 can in each case in turn be subdivided into (sub) series of specific rollers with different diameters and / or axial distances.

The guide elements of the upper guide elements series 10 are selectively depth adjustable or can be connected to the Guide elements of the lower guide elements series 9 can be approximated. An adjustment of the guide elements of the upper guide elements series 10 and thus a change of the clear receiving cross-section 12 of

Strand guiding device 6 may e.g. by means of a

hydraulic drive. One of the desired

Strand thickness d corresponding and between each other

clear receiving width 12 of the receiving shaft 11 of the strand guiding device 6 measured opposite upper and lower guide elements could e.g. be reduced from 115 mm to a range between 90 and 105 mm.

Since one guided in a narrower receiving shaft 11

Strand 3 solidifies faster and cools down, the

Casting speed and equivalent to the

Rolling 4, 5 continuous flow rate can be increased if you want to continue to bring the bottom of the strand strand as close as possible to the end of the strand guiding device 6.

To reduce the thickness of the strand 3, e.g. three to eight guide elements (pairs) of one of the mold 2 facing - but not necessarily adjoining the mold 2 - first guide segment 16 'adjustable. Alternatively, several juxtaposed guide segments 16 can be used for LCR thickness reduction, which connect directly or indirectly to the mold.

The strand thickness d or the clear receiving width 12 is dependent on the material of the strand 3 and / or in

Depending on the casting speed adjustable.

The adjustment of the respective guide elements 9, 10 takes place in a direction substantially orthogonal to the transport direction of the strand extending direction, wherein both the upper Guide elements 10 and the lower guide elements 9 can be adjustable. As can be seen in Figure 3, upper guide elements 10 are hinged to corresponding support members 17, which are preferably hydraulically adjustable. The adjustable guide elements 9, 10 are preferably in a casting plant 2 facing the front half,

preferably arranged in one of the casting plant 2 facing the front quarter of the longitudinal extent of the strand guiding device 6. The setting of the strand thickness d or the clear

Pickup width 12 may be quasi-static, i.

once, shortly after the start of casting, as soon as one of the

Pre-rolling line 4 facing head portion of the cast

Stranges 3 reaches the end of the strand guide device 6 or has passed the LCR guide elements, or also

dynamic, i. during the casting process or during the continuous quasi-stationary passage of the strand 3 through the strand guiding device 6. In the dynamic adjustment of the strand thickness d this is during the casting

Passage of a strand 3 through the

Strand guiding device 6 as often as desired, using a explained below with reference to Figure 6 relationship as a guideline changed.

4 shows a process diagram for illustrating the production method according to the invention. Based on this

Representation can be seen, why according to the invention aspired high production capacity in generic systems for the production of steel warming band only if compliance

Gießparameter proposed according to the invention, namely compared to known methods comparatively large

Strand thicknesses and large metallurgical or

Strand support lengths L can be achieved. On the ordinate of the diagram according to Figure 4, the casting speed in the unit [m / min] is plotted, while on the abscissa, the strand thickness in the unit [mm] is plotted. They are approximately parabolic lines 20a, 20b, 21a, 21b, 22a, 22b, 23a, 23b, 24a and 24b

drawn, each of which correspond to a casting characteristic at a given metallurgical or strand support length L.

In this case, several lines are shown in each case for selected strand support lengths L, since different grades of steel can be cooled at different speeds and different

Have solidification rates.

The lines 20a and 20b correspond to a strand support length L of 15.2 m, where line 20a is based on a different material-specific (global) solidification factor k than line 20b and therefore these two related lines

differ from each other.

The solidification factor k carries the unit [mm / Vmin] and is for objectively relevant steel grades between 24-27 mm / Vmin, preferably between 25 and 26 mm / Vmin.

The lines 21a and 21b correspond to a strand support length L of 17.5 m, the lines 21a and 21b analogous to the

Lines 20a and 20b turn a different one

Solidification factor k is based. The lines 22a and 22b correspond to a preferred strand support length L of 18.5 m according to the invention and again differ only with respect to a specific strand support length L of 18.5 m

Solidification factor k.

The lines 23a and 23b correspond to a particularly preferred strand support length L of 20 m and according to the invention differ again in terms of a specific

Solidification factor k.

The lines 24a and 24b correspond to a particularly preferred strand support length L of 21.6 m according to the invention and also differ with respect to a specific strand support length L of 21.6 m

Solidification factor k.

Due to the problem of the

Swamp tip position of the strand 3 it is understood that in a casting process to choose the lower casting speed, the shorter the strand support length L one

respective plant is (in the transport direction 15 over the end 14 of the strand guiding device 6 out migrating

Swamp tip would lead to bursting of strand 3).

Conversely, it can be read from the diagram according to FIG. 4 which required strand thickness one must select in an optimized casting process if one wants to cast at a desired casting speed.

If one cuts in the diagram according to FIG. the line 24 b (L = 21.6 m) by means of a vertical line at a

Strand length of 110 mm and migrates from the obtained

Intersection point to the left on the ordinate, so you get a permissible casting speed of just above 5 m / min.

The casting characteristics according to FIG. 4 are chosen purely by way of example and should not be understood as limiting. In principle, there is no fixed one for each strand thickness

Speed value, but always a corresponding speed range (and vice versa), under which the

Similarly, the strand support length L is not to be reduced to a specific value such as 18 m, for example, but it has been found that strand support lengths L, which are greater than 17.5 m (and preferably less than 23 m) already allow a significant increase in capacity over known systems.

For example, results for a strand support length L of about 22m (in the embodiment of Figure 4 on the basis of lines 24a, 24b to understand, but each one of exact

Strand support length L of 21.6) makes more sense

Casting speed range of 4.2-6.5 m / min, when a strand thickness of 96-117.5 mm is poured. Calculations have shown that e.g. at a

Strand support length L of 22 m (which essentially corresponds to the lines 24a and 24b), a generic system 1 for producing jet heating belt can reach a production capacity of about 3.8 million tons per year (mtpy), compared to systems according to the prior Technology means a big boost.

5 shows a diagram for illustrating the

Annual throughput (line 25), the casting speed (line 26) and the specific volume flow (line 27) as a function of the abscissa-applied strand thickness (with a strand width of 1880 mm).

FIG. 6 illustrates the relationship between the strand thickness d and the casting speed v _c , wherein an adjustment of (target) casting speeds v _c or (target) strand thickness d can be determined using speed factors K proposed according to the invention. The context of the attitude of the

Strand thickness d in connection with the casting speed v _c is determined by the formula stored in a facility:

v _c = [K_lowerLimit ... K_upperLimit] / d ² produced. The following information refers to a stationary continuous operation of the system, including in the present Connection operating phases are understood with a period> 10 minutes, during which the casting speed v _c (in contrast to, for example, a Angießphase) remains substantially constant. The choice of the speed factor K is in addition to the

Strand support length L in particular depending on the C content of the cast steels or on their cooling characteristics. Fast-setting steel grades allow the system to operate at relatively high casting speeds v _c , while lower casting speeds v _{c are} to be selected for slower-setting steel grades in order to prevent bulging and bursting of the strand in the area of the swamp tip. The following tables refer to strands cast steel grades that are "hard" to cool, ie quickly solidify and the

"Medium-hard" to cool, that is, a little slower to solidify.

For the speed factor K are respectively

Corridor areas indicated, within which a

casting technology operation is efficient and feasible feasible. A strand support length-specific corridor range is determined by one of the following tables

Speed factor K_upperLimit and one

Speed factor K_lowerLimit limited.

The choice of the speed factor K is dependent on the strand length L of the support and of the grade of steel, in particular from the carbon content of the cast steel, the solidification ^¬ or Umwandlungscharakterisitik whose strength or

Ductility properties and others

Material characteristics depends.

For cooling the strand 3 is on this in the field of strand guiding device 6 (between the lower end of the

Mold 2 and the pre-rolling line 4 facing the end 14 of Strand guiding device 6) a coolant, preferably water applied. The application of the coolant to the strand 3 by means of a not shown

An injection device comprising any number of spray nozzles arranged in any desired configuration (e.g., behind and / or beside and / or between the guide elements 9, 10)

includes.

For a hard cooling 3 to 4 liters of coolant per kg of extruded steel are used, for medium-hard cooling 2 to 3.5 liters of coolant per kg of extruded steel and a soft

Cooling <2.5 liters (preferably 1-2.2 liters) of coolant per kg of extruded steel. The quantities of coolant called for hard, medium hard and soft cooling overlap

due to already mentioned above constructive

Design features of the sprayer and the

Strand guiding device 6.

By example selected, essentially the same

Design and boundary conditions of the sprayer and the strand guide device 6 could be applied to realize a hard cooling 3 to 4 liters, to realize a medium-hard cooling 2 to 3 liters and to realize a soft cooling l, up to 2 liters of coolant per kg of extruded steel.

Table 1: Speed factor K for steel grades with low C content (<0.16%) and relatively hard cooling (3 - 4 1 coolant / kg extruded steel): L = 17.5 m L = 21.5 m L = 23 m

K upper limit 48900 60300 64600

K lower Limit 42000 51600 55200

Table 2: Speed factor K for steel grades with C content> 0.16% and medium-hard cooling (2 - 3.5 1 coolant / kg extruded steel):

Table 3: Speed factor K for special grades and soft cooling

(1.0 - 2.2 coolant / kg extruded steel):

L = 17.5 m L = 21.5 m L = 23 m

K upper limit 44100 54050 59000

K lower Limit 37100 44800 48900 So it is according to a preferred management in accordance with

Table l provided that for hard-to-cool strand steels, i. with application of 3 to 4 liters of coolant per kg of extruded steel, the relationship of measured in [mm]

Strand thickness d with that measured in [m / min]

Casting speed v _c according to the formula v _c = K / d ²

is complied with, with one included in the formula

Speed factor K at a preferably minimum strand support length of 17.5 m in a corridor range from 42000 to 48900, preferably in a corridor range from 45500 to 48900, while the speed factor K at a preferably maximum strand support length L _max of 23 m in a corridor range from 55200 to 64600, preferably in a corridor range from 59900 to 64600. For determining (target) casting speeds v _c or

(Target) strand thickness d for plants with between the

preferably strand support lengths Lmi _n and L _max lying

Strand support lengths L is an interpolation between the corridor areas listed above (to obtain another corridor area not shown in the tables) feasible. For example, for a strand support length L of 21.5 m for steel grades with a C content <0.16% and relatively hard cooling, a corridor range of 51600 to 60300 results. Interpolation between the corridor regions takes place in a substantially linear manner.

In the case of strand support lengths> L _max is also a

Extrapolation to the above

Corridor areas possible.

According to Table 2, for steel grades with a C content> 0.16% and medium-hard cooling, it is recommended to use a speed factor K with a strand support length L of 17.5 m from a corridor range of 39600 to 46500 and at a strand support length L of 21.5 m from a corridor range of 48300 to 57200 and at one

Strand support length L of 23 m from a corridor range of 52100 to 61900. According to Table 3, we recommend for soft to cool

Grades of steel, i. with application of 1 to 2.5 liters

Coolant per kg strand steel the use of a

Speed factor K at a strand support length L of 17.5 m from a corridor range of 37100 to 44100 and at a strand support length L of 21.5 m from a corridor range of 44800 to 54050 and at a strand support length L of 23 m from a corridor range of 48900 to 59000 ,

6 shows a diagram with characteristic curves 28-33 corresponding to the above-mentioned speed factors K. On the abscissa of the diagram is the (at the end of the strand guide device 6 or at the inlet into the

Pre-rolling line 4) strand thickness d in the unit [mm], on the ordinate the casting speed in the unit [m / min]. The curves 28, 29 and 30 apply to strand support lengths

L = 17.5 m, the characteristic curves 31, 32 and 33 for strand support lengths L = 21, 5 m.

Decisive for efficient operation of the plant are each the top, for a specific

Strand support length L valid curves, thus according to Figure 6 for strand support lengths L = 17.5 m, the characteristic curve 28 and

Strand support lengths L = 21.5 m the characteristic curve 31.

The top, for a specific strand support length L

The applicable characteristic curves correspond to the speed factors listed above in tabular form

K_upperLimit. Specifically, characteristic 28 corresponds to one Speed factor K of 48900 and characteristic 31 a speed factor K of 60300. The curves 28 and 31 thus correspond to rapidly solidifying steel grades, which allow high casting speed and heat dissipation in compliance with standardized quality criteria.

The lowest in accordance with Figure 6, for a specific

Strand support length L applicable characteristics (for

Strand support lengths L = 17.5 m: characteristic 30; For

Strand support lengths L = 21.5 m: characteristic curve 33) correspond to the speed factors listed in the table

K_lowerLimit.

The steel grades corresponding to the characteristic curves 32 and 33 are not so "hard" due to their slower solidification, i.e. not as quickly coolable as one of the characteristic curve 31

appropriate steel grade. Likewise, the grades 29 and 30 corresponding steel grades are not as cool as a corresponding characteristic 28 steel grade.

The cooling rate significantly determines the position of the sump tip within the strand 3. Above the

Steel grade specific characteristics 28-31 lying

Casting speed ranges are to be avoided in order to avoid

Bulging and bursting of strand 3 in the area of

To avoid swamp tip. In other words, the characteristics 28-31 represent limit casting speed curves for

different types of steel

In an operation identical in FIG. 6 to the starting point of an arrow 31 'with a casting speed v _c = 6.5 m / min and a strand thickness d = 104.5 mm, for example, the sump tip of the strand 3 would be at the end of FIG

Strand guiding device 6, ie as close to the entrance to the roughing mill 4, whereby an optimal exploitation of Casting heat is ensured for the subsequent rolling process. If, as shown by way of example by arrow 31 ', the casting speed v _{c is} reduced to 5 m / min for operational reasons, the strand thickness d would have to be raised to approximately 110 mm in accordance with arrow 31 "in order to continue the sump tip of the strand 3 at the end of

Strand guiding device 6 to hold and an optimal

Exploit the casting heat to ensure in the subsequent rolling process.

Conversely, when the casting speed v _{c is increased} (eg after operational problems which necessitated temporary throttling of the casting speed v _{c have} been eliminated), the strand thickness d must be correspondingly reduced.

In the case of operational reasons, which necessitate a reduction in the casting speed v _c , these may be, for example, irregularities in the area of the slide or mold, in particular at the bath level of the mold or deviations in the line temperature from predetermined values, detected by sensors.

A change in the strand thickness d can be effected by a previously described dynamic LCR thickness reduction by means of the LCR guide segment 16 '.

If the casting speed v _c falls from the preceding

down mentioned contexts, the

Operating team pointed out by a spending facility to the Liquid Core Reduction (LCR) so too

reduce that the strand thickness d increases, and so the context of the invention or a respective

Corridor area to reach again. In accordance with the invention, it is preferable to aim for an upper region of the corridor. Depending on what is considered by the operators as the main parameter of the plant (the strand thickness d or the

Casting speed v _c ), starting from a desired strand thickness d a corresponding target casting speed v _c can be selected or it can be based on a

desired casting speed v _c the strand thickness d

be varied accordingly.

It should be noted that in terms of a high

Operational stability previously described changes in the strand thickness d only for relevant changes in

Casting speed v _c (eg for changes of v _c by approx.

0.25 m / min) and not at each

slight deviation of the casting speed v _c from a respectively desired target casting speed.

Based on the characteristic curves according to the invention or on the corresponding speed factors K, the strand thickness d can be increased as the casting speed v _c decreases, thereby increasing the material throughput and thus

be optimized.

Since a casting speed v _c above about 7 m / min are hardly accessible for stable casting, this became

Area hidden from the diagram of Figure 6.

Claims

claims

1. A process for the continuous or semi-continuous production of steel heat-tape, which starting from a strand guided by a strand guiding device (6)

(3) is rolled in a roughing train (4) to an intermediate strip (3 ') and subsequently in a finishing train (5) to an end strip (3''), characterized in that in a mold (2) of a casting plant cast strand (3) has a strand thickness (d) between 105 and 130 mm, preferably a strand thickness (d) between 115 and 125 mm, and liquid-core reduction (LCR) method by means of the subsequent strand guiding device (6) in liquid Cross-sectional core of the strand (3) is reduced to a strand thickness (d) between 85 and 120 mm, preferably to a strand thickness (d) between 95 and 115 mm, one between the meniscus (13), ie the bath level of the mold (2) and a strand support length (L) measured at an end (14) of the strand guiding device (6) facing the rough rolling mill (4) is greater than or equal to 18.5 m, preferably in a range between 18.7 and 23 m, particularly preferably between 20.1 and 23 m, lies, with a Gießgeschwi (v _c ) is in a range of 3.8 - 7 m / min and where. Strands (3) with different strand thicknesses (d) in

Cast depending on the following casting speeds become :

at casting speeds between 5, 0 and 5, 9 m / min with 85-110 mm strand thickness, preferably with 95-110 mm strand thickness,

2. The method according to claim 1, characterized in that in the roughing train (4) is a rough rolling of the strand (3) to an intermediate belt (3 ') in at least four rolling passes, ie using four Vorwalzgerüsten (4i, 4 ₂ , 4 _3rd 4 ₄ ), preferably in five rolling passes, ie using five roughing stands (4i, 4 ₂ , 4 ₃ , 4 ₄ , 4 s).

3. The method according to claim 2, characterized in that in the roughing train (4) taking place roll passes within a maximum of 80 seconds, preferably within a maximum of 50 seconds.

4. The method according to claim 2 or 3, characterized in that the first rolling pass in the roughing train (4) within a maximum of 7 minutes, preferably within a maximum of 6.2 minutes from the start of solidification of the mold in the mold (2) liquid strand (3 ) he follows. Method according to one of claims 1 to 4, characterized in that between the end (14) of

Strand guiding device (6) and an inlet region of the roughing train (4) only one by a

Ambient temperature conditioned cooling of the strand (3) is allowed.

Method according to one of claims 1 to 5, characterized in that in the roughing train (4) per

Rolling a reduction in the thickness of the strand (3) by 35- 60%, preferably by 40-55% takes place.

Method according to one of claims 1 to 6, characterized in that a cooling of the from

Pre-rolling (4) exiting intermediate belt (3 ') under a cooling rate of not more than 3 K / m, preferably at a cooling rate of not more than 2.5 K / m.

Method according to one of claims 1 to 7, characterized in that a heating of the from

Pre-rolling line (4) leaked intermediate band (3 ') by means of an inductive heating device (7), preferably in the transverse field heating method, starting at a

Temperature above 770 ° C, preferably above 820 ° C to a temperature of at least 1110 ° C,

preferably to a temperature of above 1170 ° C.

9. The method according to claim 8, characterized in that the heating of the intermediate strip (3 ') within a period of 4 to 25 seconds, preferably within a period of 5 to 13 seconds. 10. The method according to claim 2 and 8, characterized in that when making exactly four rolling passes in the

Pre-rolling line (4) is provided, that the passage of time between the first pass and the entry into the

Heating device (7) at intermediate strip thicknesses of 5-10 mm not longer than 105 seconds, preferably not longer than 70 seconds.

11. The method according to any one of claims 1 to 10, characterized

characterized in that a finish rolling of the heated

Intermediate belt (3 ') in the finishing train (5) in four rolling passes, i. using four

Finish rolling stands (5i, 5 ₂ , 5 ₃ , 5 ₄ ) or in five

Rolling passes, i. using five

Fertigwalzgerüsten (5i, 5 ₂ , 5 _3i 5 ₄ , 5 ₅ ) to an end strip (3 '') with a thickness <1.5 mm, preferably <1.2 mm.

12. The method according to claim 11, characterized in that within the finishing train (5) performed rolling passes within a period of maximum 16 Seconds, preferably within a maximum period of 8 seconds.

13. The method according to any one of claims 1 to 12, characterized

characterized in that for LCR thickness reduction of

Stranges (3) for contacting predetermined

Guide elements (9, 10) of the strand guiding device (6) relative to a longitudinal axis of the strand (3) are adjustable, wherein an adjustment of the guide elements (9, 10) depending on the material of the strand (3) and / or the casting speed (v _c ) is made.

14. The method according to claim 13, characterized in that the strand thickness (d) quasi-static after the beginning of a casting sequence, i. shortly after the exit of the strand (3) from the mold (2) is adjustable. A method according to claim 13, characterized in that the strand thickness (d) is dynamically adjustable, i. during the casting process or during the passage of the

Stands (3) by the strand guiding device (6) is arbitrarily variable. 16. The method according to any one of claims 1 to 15, characterized

in that, by means of an injection device in the region of the strand guiding device (6), hard-to-cool strand steels, ie with the application of 3 to 4 liters of coolant per kg of strand steel, in a stationary continuous operation of the plant, the relationship between a measured in [mm] strand thickness (d) with the measured in [m / min] casting speed (v _c ) according to the formula v _c = K / d ^{2 is} maintained, wherein a speed factor contained in the formula (K) at one

Strand support length (L) = 17.5 m in a corridor range of 42000 to 48900, preferably in a corridor range of 45500 to 48900, while the speed factor

(K) at a strand support length (L) = 23 m in one

Corridor range from 55200 to 64600, preferably in a corridor range from 59900 to 64600, wherein for determining (target) casting speeds (v _c ) or

(Target) strand thicknesses (d) for plants with between the

Strand support lengths L = 17.5 m and L = 23 m

Strangstützlängen (L) an interpolation between the corridor areas mentioned above is feasible.

17. The method according to any one of claims 1 to 15, characterized in that medium-hard to be cooled by means of a spraying device in the region of the strand guiding device (6) strand steels, i. applying 2 to 3.5 liters of coolant per kg of extruded steel, in one

stationary-continuous operation of the plant

Context of a strand thickness (d) measured in [mm] with the casting speed (v _c ) measured in [m / min] the formula v _c = K / d ^{2 is} maintained, wherein a speed factor (K) contained in the formula at a strand support length (L) of 17.5 m in a corridor range from 39600 to 46500, preferably in one

Corridor range from 43050 to 46500, while the speed factor (K) at a strand support length (L) = 23 m in a corridor range from 52100 to 61900, preferably in a corridor range from 57000 to 61900, wherein for determining (target) casting ^¬ velocities (v _c ) or (target) strand thicknesses (d) for installations with strand support lengths (L) lying between the strand support lengths L = 17.5 m and L = 23 m, interpolation can be carried out between the previously mentioned corridor areas.

18. The method according to any one of claims 1 to 15, characterized in that for by means of a spraying device in the region of the strand guiding device (6) soft-to-cool strand steels, i. with application of less than 2.2 liters of coolant per kg of extruded steel, in a stationary-continuous operation of the plant

Context of a measured in [mm] strand thickness (d) with the measured in [m / min] casting speed (v _c ) according to the formula v _c = K / d ^{2 is} maintained, wherein a speed factor contained in the formula (K) at a Strand support length (L) of 17.5 m in a corridor area from 37100 to 44100, preferably in a corridor range from 40600 to 44100, while the

Speed factor (K) at a strand support length (L) = 23 m in a corridor range from 48900 to 59000, preferably in a corridor range from 53950 to 59000, wherein for determining (target) casting ^¬ speeds (v _c ) or (target -) strand thicknesses (d) for systems with strand support lengths (L) lying between the strand support lengths L = 17.5 m and L = 23 m, an interpolation between the corridor regions specified above can be carried out.

19. Annex to the implementation of a procedure for

Continuous or semi-continuous production of steel hot strip according to one of claims 1 to 18, comprising a mold (2), one of these downstream

Strand guiding device (6), one of these downstream Vorwalzstraße (4), one of these downstream, preferably inductive heating device (7) and one of these

downstream finishing train (5), wherein the

Strand guiding device (6) a series at the bottom

Guide elements (9) and one in parallel or

converging series at upper

Guide elements (10) and between the two guide element series (9, 10) for receiving a from the mold (2) emerging strand (3) provided Receiving shaft (11) is formed, which by

Training different distances between opposing guide elements (9, 10) to each other in the transport direction of the strand (3) is at least partially tapered and thereby the strand (3) thickness is reduced, characterized in that the clear receiving width (12) of the receiving shaft (11) at its the Mold (2)

Assigning input range between 105 and 130 mm, preferably between 115 and 125 mm, that the receiving shaft (11) at its pre-rolling line (4) facing end (14) one of the strand thickness (d) of

Stranges (3) corresponding clear receiving width (12) between 85 and 120 mm, preferably between 95 and 115 mm, one between the meniscus (13), d.i. the bath level of the mold (2) and the strand support length (L) measured at the end (14) of the receiving shaft (11) of the strand guide device (6) is greater than or equal to 18.5 m, preferably in a range between 18, 7 and 23 m, more preferably between 20.1 and 23 m, and wherein a

Control device is provided, by means of which the casting speed (v _c ) of the strand (3) in a range between 3.8 - 7 m / min is durable.

20. Plant according to claim 19, characterized in that the roughing train (4) four or five roughing stands (4i,

4 ₂ , 4 ₃ , 4 ₄ , 4 ₅ ).

21. Plant according to one of claims 19 or 20, characterized

characterized in that between the end (14) of the

Receiving shaft (11) and the strand guiding device (6) and an inlet region of the roughing train (4) no cooling device, but a thermal cover

is provided, which at least partially surrounds a conveying device provided for transporting the strand (3).

22. Plant according to one of claims 19 to 21, characterized

in that by means of pre-rolling stands (4i, 4 ₂ , 4 _3i 4 ₄ , 4 ₅ ) arranged in the roughing train (4) a

Reduction of the thickness of the strand (3) by 35-60%, preferably by 40-55% per roughing stand (4i, 4 ₂ ,

4 ₃ , 4 ₄ , 45) is feasible, so that an intermediate band (3 ') with a thickness of 3 to 15 mm, preferably with a thickness of 4 to 10 mm can be generated.

23. Plant according to one of claims 19 to 22, characterized

characterized in that the heating device (7) as

inductive transverse field heating furnace is formed, by means of which the strand (3), starting at a temperature above 770 ° C, preferably above 820 ° C. a temperature of at least 1110 ° C, preferably to a temperature of above 1170 ° C can be heated.

24. Plant according to one of claims 19 to 23, characterized

characterized in that the finishing train (5) four

Finish rolling stands (5i, 5 ₂ , 53, 5 ₄ ) or five

Roughing stands (5i, 5 ₂ , 5 ₃ , 5 ₄ , 5 ₅ ) comprises, by means of which one of the roughing train (4) exiting

Intermediate band (3 ') to an end band (3' ') with a thickness of <1.5 mm, preferably <1.2 mm can be reduced.

25. Plant according to claim 24, characterized in that the finishing mills (5i, 5 ₂ , 5 _3i 5 ₄ , 5 ₅ ) in each case at intervals of <7 m, preferably at intervals of <5 m are arranged to each other, wherein the distances between the work roll axes of the finishing mills (5i, 5 ₂ , 5 _3i 5 ₄ , 5 ₅ ) are measured.

26. Plant according to one of claims 19 to 25, characterized

characterized in that to reduce the thickness of the strand (3) certain guide elements (9, 10) adjustable and thereby a clear receiving width (12) of the

Receiving shaft (11) can be reduced or enlarged, wherein the strand thickness (d) or the clear receiving width (12) in dependence of the material of the strand and / or the casting speed is adjustable.

27. Plant according to claim 26, characterized in that the adjustable guide elements (9, 10) in one of the mold (2) facing the front half, preferably in one of the mold (2) facing the front quarter of the longitudinal extension of the strand guide device (6) are arranged ,

28. Plant according to one of claims 20 to 27, characterized

characterized in that a work roll axis of the strand guide device (6) next adjacent first roughing stand (4i) of the rough rolling mill (4) a maximum of 7 m, preferably a maximum of 5 m after the end (14) of

Strand guiding device (6) is arranged.

29. Plant according to one of claims 19 to 28, characterized

characterized in that a pre-rolling facing inlet end (7a) of the heating device (7) is arranged at most 25 m, preferably not more than 19 m after the work roll axis of the heating device (7) nearest roughing stand.