Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/12—Accessories for subsequent treating or working cast stock in situ
  • B22D11/1206—Accessories for subsequent treating or working cast stock in situ for plastic shaping of strands
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
  • B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
  • B21B1/463—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a continuous process, i.e. the cast not being cut before rolling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/12—Accessories for subsequent treating or working cast stock in situ
  • B22D11/128—Accessories for subsequent treating or working cast stock in situ for removing
  • B22D11/1282—Vertical casting and curving the cast stock to the horizontal
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/16—Controlling or regulating processes or operations
  • B22D11/22—Controlling or regulating processes or operations for cooling cast stock or mould
  • B22D11/225—Controlling or regulating processes or operations for cooling cast stock or mould for secondary cooling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B2201/00—Special rolling modes
  • B21B2201/14—Soft reduction

Definitions

• the invention relates to methods and a device for producing a strand of metal by means of a continuous casting plant, which has at least one cow device for cooling the strand, the cow device being assigned at least one reduction framework for reducing the thickness of the strand, the strand being a solidified shell during the thickness reduction and has a liquid core.
• the strand For the production of strands, it is known to associate or assign a reduction framework to a continuous casting plant. A particularly large reduction in thickness is achieved if the strand has a still liquid core when it runs in, the reduction framework. In this process, which is known as so-called soft reduction, it is important that the liquid core is large enough to ensure the necessary reduction in the thickness of the strand, but also not so large that it leads to strand breakthrough and leakage of liquid Metal is coming. To achieve the necessary dimension of the liquid core when the reduction framework is reached, the strand is cooled by means of a cooling device, the necessary cooling being set by an operator after the operator has estimated the dimension of the liquid core.
• the object of the invention is to provide a method and a device for carrying out the method, which permits a soft reduction which is improved compared to the prior art, in particular also with varying strand speed.
• the object is achieved according to the invention by a method according to claim 1 or a device according to claim 10.
• the cooling device is followed by at least one reduction frame for reducing the thickness of the strand, the strand showing a solidified shell and a liquid core in the thickness reduction, and wherein the cooling by means of a temperature and solidification model is set in such a way, in particular automatically, that the
• the solidification limit between the solidified shell and the liquid core when the strand enters the reduction framework corresponds to a predetermined target solidification limit between the solidified shell and the liquid core.
• a particularly good soft reduction is achieved in this way.
• reduction stands in the sense of the invention can be complex roll stands by means of which a certain geometry is rolled into the strand.
• the temperature and solidification model can be, for example, an analytical model, a neural network or a combination of an analytical model and a neural network.
• the temperature and solidification model advantageously relates the cooling of the strand and the solidification limit between the solidified shell and the liquid core.
• Such an embodiment of the invention is particularly advantageous since the temperature and solidification model depicts the solidification limit between the solidified shell and the liquid core as a function of the cooling quantity, the cause-effect relationship between cooling and the solidification limit between the solidified shell and the liquid core ,
• the solidification limit between the solidified shell and the liquid core is dependent on the cooling of the strand, in particular in real time and continuously, and the necessary cooling of the strand is determined iteratively depending on the predetermined set solidification limit between the solidified shell and the liquid core, iterating as often until the deviation of the solidification limit determined with the temperature and solidification model between of the solidified shell and the liquid core of the predetermined target solidification limit between the solidified shell and the liquid core is smaller than a predetermined tolerance value.
• the variables strand geometry, strand shell thickness, time, strand material, coolant pressure or volume and coolant temperature are used to determine the necessary cooling of the strand depending on the solidification limit between the solidified shell and the liquid core.
• the use of these sizes is particularly suitable for achieving particularly precise cooling of the strand.
• each reduction device is assigned a set solidification limit between the solidified shell and the liquid core of the strand.
• the effect of the thickness reduction by the reduction framework in particular the position, is shown in the temperature and solidification model the boundary between the solidified shell and the liquid core is also modeled.
• the reduction in thickness is modeled by the reduction framework by at least one of the large reduction force and degree of reduction.
• At least one of the large reduction force and degree of reduction in the reduction framework is measured and used to adapt the temperature and solidification model.
• the quantities reduction force and degree of reduction in the reduction framework are measured and used to adapt the temperature and solidification model.
• FIG. 1 shows a continuous casting installation
• FIG. 2 shows a flowchart for iteratively determining a target cooling of the strand using a temperature and solidification model
• FIG. 3 shows a flowchart for iteratively determining an adaptation coefficient.
• Reference numeral 1 designates the cast strand which has a solidified shell 21 within a solidification limit 22 and a liquid core 2.
• the strand is moved with drive or guide rollers 4 and cooled on its way through cow devices 5. These are advantageously designed as water spray devices.
• cow devices 5 are divided into cooling segments. This division is not necessary in the new and inventive method, but can be taken into account.
• Both the drive rollers 4 and the cow devices 5 are connected in terms of data technology to a computing device. In the present exemplary embodiment, both are technically connected to one and the same automation device 7.
• the automation device 7 optionally also has a terminal, not shown, and a keyboard, not shown.
• the automation device 7 is connected to a superordinate computing system 8.
• the material required for continuous casting, in this case liquid steel, is fed via a feed device 20.
• the manipulated variables for the cow devices 5 are calculated by means of a temperature and solidification model, ie a thermal model of the strand, which is implemented on the superordinate computer system 8 in the exemplary embodiment.
• Reference numerals 9, 10 and 11 designate reduction frameworks assigned to the cooling device 5. In an advantageous embodiment of the invention, these are connected to the programmable logic controller 7 in terms of data technology, the rolling force and the degree of reduction, for example in the form of the roll gap, being transmitted to the automation device 7.
• three reduction frameworks 9, 10 and 11 are provided.
• so-called soft reduction is carried out only in the reduction frameworks 9 and 10.
• the strand to be reduced is not completely solidified, but has a liquid core 2 and a solidified shell 21 when it enters a reduction framework.
• only a soft reduction in the reduction frameworks 9 and 10 is provided for the strand 1.
• the cooling with the cow devices 5 is set by means of the automation device 7 in such a way that that the solidification limit 22 between the solidified shell 21 and the liquid core 2 of the strand 1 corresponds to a desired set solidification limit between the liquid core 2 and the solidified shell 21 when it enters the reduction frames 9 and 10.
• the reduction frame 9 is arranged in a particularly advantageous manner within the cooling section, i.e. cooling devices 5 are provided in front of and behind the reduction frame 9. It can also be provided in an advantageous manner to also provide 10 cooling devices behind the second reduction frame.
• the cooling device 9 is advantageously not arranged in the bend of the strand 1, as is indicated for reasons of clarity in FIG. 1, but is arranged in front of the bend of the strand or behind the bend of the strand 1.
• the solidification limits e x in the strand are determined in the temperature and solidification model 13 from a given cooling of the strand k ⁇ by means of the temperature and solidification model 13.
• This solidification limit e x is compared in a comparator 14 with the set solidification limit eo in the strand.
• the comparator 14 asks whether I ⁇ i-eol ⁇ ⁇ e max , where ⁇ e max is a predetermined tolerance value.
• the function block 12 determines a new proposal k for improved cooling of the strand.
• a value for the cooling is used as the initial value for the iteration, which has proven to be a tried and tested experience in the long-term average. If the magnitude of the difference between e ⁇ and e 0 is less than or equal to the tolerance value ⁇ e max , the target value k 0 for the cow the string is set equal to the value.
• the values e lf e 0 , ⁇ e max , k ⁇ r k 0 are not necessarily scalars, but column matrices with one or more values. For example, B.
• the iteration circuit shown in FIG. 2 takes place on the basis of genetic algorithms. This is particularly useful when k x or k 0 are column matrices with many elements.
• the temperature and solidification model 13 can be implemented both as a one-dimensional model and as a two-dimensional model.
• the thermal conduction equation is the basis of the temperature and solidification model, shown here for the two-dimensional case
• T is the temperature
• t is the time
• a is the temperature conductivity
• x and y are the two-dimensional spatial coordinates.
• the cross-section of the strand skin is divided into small rectangles of the size ⁇ x times ⁇ y and the temperature is calculated in small time steps ⁇ t.
• ⁇ is assumed to be constant and Tu is equated to the temperature of the cooling water in the mold.
• Tu is equated to the temperature of the coolant and ⁇ is, for example, according to
• V is the coolant volume in - ⁇ .
• D min at V can be specified differently for each point on the strand surface, which means that the model can also be used to describe nozzle characteristics.
• the model also calculates the course of the solidification limit from the course of the temperature distribution in the strand.
• the individual model parameters include:
• the solidification limits e x in the strand are determined in the temperature and solidification model 13 from a given cooling of the strand by means of the temperature and solidification model 13.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Continuous Casting (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Heat Treatment Of Strip Materials And Filament Materials (AREA)

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Publications (2)

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• 1999
  • 1999-07-07 DE DE19931331A patent/DE19931331A1/de not_active Ceased
• 2000
  • 2000-06-29 WO PCT/DE2000/002117 patent/WO2001003867A1/fr active IP Right Grant
  • 2000-06-29 AT AT00951251T patent/ATE229392T1/de active
  • 2000-06-29 RU RU2002103039/02A patent/RU2245214C2/ru not_active IP Right Cessation
  • 2000-06-29 US US10/030,340 patent/US6880616B1/en not_active Expired - Lifetime
  • 2000-06-29 DE DE50000941T patent/DE50000941D1/de not_active Expired - Lifetime
  • 2000-06-29 EP EP00951251A patent/EP1200216B1/fr not_active Expired - Lifetime

Non-Patent Citations (1)

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