CA2305401A1 - Method for determining and controlling material flux of continuous cast slabs - Google Patents
Method for determining and controlling material flux of continuous cast slabs Download PDFInfo
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- CA2305401A1 CA2305401A1 CA002305401A CA2305401A CA2305401A1 CA 2305401 A1 CA2305401 A1 CA 2305401A1 CA 002305401 A CA002305401 A CA 002305401A CA 2305401 A CA2305401 A CA 2305401A CA 2305401 A1 CA2305401 A1 CA 2305401A1
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- Prior art keywords
- slab
- temperature
- continuous
- material flow
- slabs
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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
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0081—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for slabs; for billets
-
- 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
- B21B1/466—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 non-continuous process, i.e. the cast being cut before rolling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/005—Control of time interval or spacing between workpieces
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D11/00—Process control or regulation for heat treatments
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Crystallography & Structural Chemistry (AREA)
- Thermal Sciences (AREA)
- Physics & Mathematics (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Continuous Casting (AREA)
- Metal Rolling (AREA)
- Control Of Metal Rolling (AREA)
- Feedback Control In General (AREA)
- Control Of Heat Treatment Processes (AREA)
Abstract
The invention relates to a method for determining and controlling the material flux of continuous cast slabs, in particular steel slabs, by tracking and optimizing the temperature on their transport path between the continuous casting machine and the rolling mill. The known temperature of the liquid phase at the casting die exit of the continuous casting plant and the physical parameters of the slab are used as starting points in order to determine the heat amount and the temperature profile of the slab. The convective intermixture of the heat quantity contained in the slab and the time-dependent heat loss of the slab, which is inhomogeneously cooling to the surrounding medium, are then calculated by means of a mathematical/physical model. The result of the calculation is used, optionally together with the measured surface temperature of the slab, in order to control the flux of material in an existing slab tracking system.
Description
~~ 72118 Method for deterrlining and controlling the material flow of continuous-cast slabs Description The invention relates to a method for determining and controlling the material flow of continuous-cast slabs, in particular steel :labs, by monitoring and optimizing the temperature on the>ir transport path between the continuous-casting installation and the rolling mill.
For the operator of a continuous-casting installation with connected rolling mill, and for projecting slab continuous-casting finishing bays as a link between the continuous-casting installation and the rolling mill, it is becoming increasingly important to know the heat content which is present i.n the slab which has just been cast or is being temporarily stored, in order to bring the slab into a material flow which corresponds to the heat content still present therein in an economical optimum manner. Since a slab which has just been cast has an inhomogeneous temperature profile which, over a prolonged period, strives to achieve a more homogenous temperature profile, it is not possible to draw conclusions about the mean slab temperature using measurable surface temperatures. Therefore, it is also impossible to be certain of the slab temperature profile ' - 2 -after a certain time, for example in order to bring the slab to an optimum, homogenous rolling temperature via a reheating fixture. Finally, the solidified slab which leaves the caster passes through different transport and processing paths, which each lead to different slab temperature profiles.
Differences in the' temperature profile arise depending on whether the slab is transported on a roller table with or without thermal insulation, whether one or more slabs are stored in the stack, whether the slabs are stored in an open slab yard or in an open or closed holding pit. Different temperature profiles also result for slabs which have undergone accelerated cooling in a water immersion basin compared to those which have undergone slower cooling in a water-spraying in~;tallation. It is therefore clear that it is desirable to find and be aware of the cooling profile of the various slabs, in order to use this knowledge in a targeted manner for material monitoring and controlling the material flow, which were hitherto carried out predominantly on the basis of experience and tests.
In view of the above problems, the object of the present invention is to find a method for determining and controlling the material flow of continuous-cast slabs, in particular steel ,labs, which enables the amount of heat and the temperature profile of a continuous-cast slab on its path between the contir..uous-casting installation and the rolling mill to be determined and used in a targeted manner, in order ' _ 3 _ for the values found to be used in an existing slab-monitoring s~~stem, in order to obtain a material flow which is optimum in terms of energy, i.e. is economical and safe.
To achieve' the object, it is proposed, according to the invention, that to determine the amount of heat and the temperature profile of the slab, starting from the known temperature of the liquid phase at the mold exit of the continuous-casting installation and given knowledge of the physical parameters of the slab, the convective mixing of the amount of heat contained in the slab and the time-dependent heat loss from the inhomogeneously cooling slab to the surrounding medium are calculated by means of a mathematical-physical model, and the result of the calculation, if appropriate together with the measured surface temperature of the slab, is used to control the material flow in an existing slab-monitoring system.
The proposal of the invention makes it possible to guide a slab in a controlled manner through the various material flows, such as warm charge rolling, hot charge rolling, cold charge rolling or hot direct rolling, from the continuous-casting installation into the rolling mill. It is possible both to find the cooling profile of various slabs in the stack and to determine the profile of cooling at the surface of various slabs, in order to draw a conclusion concerning the temperature in the interior of the slab using _ 4 _ control measurements. The calculated values and additional production data of. the installation can be used, for example, to determine the size of the holding pit and, in operation, to predict hot batches at different mean temperatures.
In a preferred configuration of the method according to the invention, there is provision for the two-dimensional finite element method to be used to calculate the mathematical-physical model. Finite element calculation methods enable a zTery wide range of operations to be simulated, thus a~~sisting with design developments, handling operations, sales and, in the present case, also the future plant operator. In the design phase, the method is frequently used to reveal anct minimize possible risks through structural mechanics analyses>. It can be used to carry out deformation and stress analyses, temperature calculations, thermomechanical ~>imulations and also to determine eigenfrequencies wind eigenforms, with the aim of structural optimization. Simulations based on finite element calculations are often demanded by plant operators as early as the project phase and are frequently included in the supply contract of: the plant as a fixed component of the contract.
Calculatic>ns using the finite element method are also carried out during the development of mathematical-physical models which have to provide accurate results on-line within a very short time, predominantly parameter studies, from the results of which analytic formulae are then derived.
For the present invention, the two-dimensional finite element method, tree finite difference method or software using formulae derived from off-line studies are used to calculate the mathematical-physical model.
A universal, commercially available finite element package can be usE>d in off-line studies to implement the method. On line, this package is probably too large and too slow. Therefore, i_t is appropriate to use, i.e. program, a method (this may also be a finite element method or the finite difference method) which is specifically adapted to the slab geometry (rectangular) and is therefore quick enough. The on-line method can be checked using the off-line finite element package.
The physical parameters of the slab used are preferably the ter~iperature-dependent material values density p, the specific heat cP, the thermal conductivity ~, and scale properties.
According to the invention, to optimize the method, the result of the calculation and the measured surface temperature of the slab are linked to automation of the material flow in the slab-monitoring system.
The invention advantageously makes it possible, by means of the mathematical-physical model, preferably using a finite element sirr~ulation or finite difference method, to determine the temperature profile of slabs and stacks of slabs of different. dimensions under specific cooling conditions. Through evaluation of the profiles of the mean slab temperature and selected surface temperatures over time, it is subsequentl~r possible to make a good estimation of the mean slab temperatures by measuring the surface temperature.
For example, the result of the method according to the invention can be used to draw conclusions as to how many hours a fixed mean slab temperature is maintained in the finishing bay; it is possible to draw conclusions concerning the entire temperature spectrum in the slab-monitoring system. It has emerged that the method according to the invention and the above-described calculation method are very flexible in use and are suitable for achieving the object of the invention, i.e. that of enabling economical and reliable material flow between the continuous-casting installation and the rolling mill. The invention is able to replace the previous slab control method which was based on experience and empirical values. The installations no longer have to be overdimensioned for safety reasons, because with the method according to the invention it is now possible to determine and control the actual conditions for the material flow between continuous;-casting installation and rolling mill.
The invention is easiest to explain with reference to a practical example. In the example, it is assumed that a plurality of continuous-cast slabs are stored in a stack in an open holding p=Lt. The mean cooling profile of the various slabs in the stag; is to be determined, as is the profile of cooling at the surfaces of various slabs in the stack. The aim of an application could be to determine the size of a holding pit or to predict hot batches of slabs at different mean temperatures during ongoing production.
Working on the basis of a model as described above, by way of example thirteen slabs each with 420 elements are discretized. It i:~ sufficient to model one half of a slab given symmetrical boundary conditions and, for example, to generate the finite element network in such a way that the mean temperature and the time-dependent control of the stacking operation can subsequently be determined with ease.
The simulation can be divided up as follows:
1. Monitoring of the temperature of the slab cross section a~; it passes through the caster, corresponding to the starting temperature profile for each individual slab at the start of the stack.
For the operator of a continuous-casting installation with connected rolling mill, and for projecting slab continuous-casting finishing bays as a link between the continuous-casting installation and the rolling mill, it is becoming increasingly important to know the heat content which is present i.n the slab which has just been cast or is being temporarily stored, in order to bring the slab into a material flow which corresponds to the heat content still present therein in an economical optimum manner. Since a slab which has just been cast has an inhomogeneous temperature profile which, over a prolonged period, strives to achieve a more homogenous temperature profile, it is not possible to draw conclusions about the mean slab temperature using measurable surface temperatures. Therefore, it is also impossible to be certain of the slab temperature profile ' - 2 -after a certain time, for example in order to bring the slab to an optimum, homogenous rolling temperature via a reheating fixture. Finally, the solidified slab which leaves the caster passes through different transport and processing paths, which each lead to different slab temperature profiles.
Differences in the' temperature profile arise depending on whether the slab is transported on a roller table with or without thermal insulation, whether one or more slabs are stored in the stack, whether the slabs are stored in an open slab yard or in an open or closed holding pit. Different temperature profiles also result for slabs which have undergone accelerated cooling in a water immersion basin compared to those which have undergone slower cooling in a water-spraying in~;tallation. It is therefore clear that it is desirable to find and be aware of the cooling profile of the various slabs, in order to use this knowledge in a targeted manner for material monitoring and controlling the material flow, which were hitherto carried out predominantly on the basis of experience and tests.
In view of the above problems, the object of the present invention is to find a method for determining and controlling the material flow of continuous-cast slabs, in particular steel ,labs, which enables the amount of heat and the temperature profile of a continuous-cast slab on its path between the contir..uous-casting installation and the rolling mill to be determined and used in a targeted manner, in order ' _ 3 _ for the values found to be used in an existing slab-monitoring s~~stem, in order to obtain a material flow which is optimum in terms of energy, i.e. is economical and safe.
To achieve' the object, it is proposed, according to the invention, that to determine the amount of heat and the temperature profile of the slab, starting from the known temperature of the liquid phase at the mold exit of the continuous-casting installation and given knowledge of the physical parameters of the slab, the convective mixing of the amount of heat contained in the slab and the time-dependent heat loss from the inhomogeneously cooling slab to the surrounding medium are calculated by means of a mathematical-physical model, and the result of the calculation, if appropriate together with the measured surface temperature of the slab, is used to control the material flow in an existing slab-monitoring system.
The proposal of the invention makes it possible to guide a slab in a controlled manner through the various material flows, such as warm charge rolling, hot charge rolling, cold charge rolling or hot direct rolling, from the continuous-casting installation into the rolling mill. It is possible both to find the cooling profile of various slabs in the stack and to determine the profile of cooling at the surface of various slabs, in order to draw a conclusion concerning the temperature in the interior of the slab using _ 4 _ control measurements. The calculated values and additional production data of. the installation can be used, for example, to determine the size of the holding pit and, in operation, to predict hot batches at different mean temperatures.
In a preferred configuration of the method according to the invention, there is provision for the two-dimensional finite element method to be used to calculate the mathematical-physical model. Finite element calculation methods enable a zTery wide range of operations to be simulated, thus a~~sisting with design developments, handling operations, sales and, in the present case, also the future plant operator. In the design phase, the method is frequently used to reveal anct minimize possible risks through structural mechanics analyses>. It can be used to carry out deformation and stress analyses, temperature calculations, thermomechanical ~>imulations and also to determine eigenfrequencies wind eigenforms, with the aim of structural optimization. Simulations based on finite element calculations are often demanded by plant operators as early as the project phase and are frequently included in the supply contract of: the plant as a fixed component of the contract.
Calculatic>ns using the finite element method are also carried out during the development of mathematical-physical models which have to provide accurate results on-line within a very short time, predominantly parameter studies, from the results of which analytic formulae are then derived.
For the present invention, the two-dimensional finite element method, tree finite difference method or software using formulae derived from off-line studies are used to calculate the mathematical-physical model.
A universal, commercially available finite element package can be usE>d in off-line studies to implement the method. On line, this package is probably too large and too slow. Therefore, i_t is appropriate to use, i.e. program, a method (this may also be a finite element method or the finite difference method) which is specifically adapted to the slab geometry (rectangular) and is therefore quick enough. The on-line method can be checked using the off-line finite element package.
The physical parameters of the slab used are preferably the ter~iperature-dependent material values density p, the specific heat cP, the thermal conductivity ~, and scale properties.
According to the invention, to optimize the method, the result of the calculation and the measured surface temperature of the slab are linked to automation of the material flow in the slab-monitoring system.
The invention advantageously makes it possible, by means of the mathematical-physical model, preferably using a finite element sirr~ulation or finite difference method, to determine the temperature profile of slabs and stacks of slabs of different. dimensions under specific cooling conditions. Through evaluation of the profiles of the mean slab temperature and selected surface temperatures over time, it is subsequentl~r possible to make a good estimation of the mean slab temperatures by measuring the surface temperature.
For example, the result of the method according to the invention can be used to draw conclusions as to how many hours a fixed mean slab temperature is maintained in the finishing bay; it is possible to draw conclusions concerning the entire temperature spectrum in the slab-monitoring system. It has emerged that the method according to the invention and the above-described calculation method are very flexible in use and are suitable for achieving the object of the invention, i.e. that of enabling economical and reliable material flow between the continuous-casting installation and the rolling mill. The invention is able to replace the previous slab control method which was based on experience and empirical values. The installations no longer have to be overdimensioned for safety reasons, because with the method according to the invention it is now possible to determine and control the actual conditions for the material flow between continuous;-casting installation and rolling mill.
The invention is easiest to explain with reference to a practical example. In the example, it is assumed that a plurality of continuous-cast slabs are stored in a stack in an open holding p=Lt. The mean cooling profile of the various slabs in the stag; is to be determined, as is the profile of cooling at the surfaces of various slabs in the stack. The aim of an application could be to determine the size of a holding pit or to predict hot batches of slabs at different mean temperatures during ongoing production.
Working on the basis of a model as described above, by way of example thirteen slabs each with 420 elements are discretized. It i:~ sufficient to model one half of a slab given symmetrical boundary conditions and, for example, to generate the finite element network in such a way that the mean temperature and the time-dependent control of the stacking operation can subsequently be determined with ease.
The simulation can be divided up as follows:
1. Monitoring of the temperature of the slab cross section a~; it passes through the caster, corresponding to the starting temperature profile for each individual slab at the start of the stack.
2. Simulation of the stack of the individual slabs.
3. Simulation: of the cooling of the stack of slabs.
In the first substep, the solidification of the slab in the caster is simulated in order to generate an entry temperature profile of the slabs in the holding pit which is close to reality. The material density, specific heat and thermal conductivity are temperature-dependent.
_ g _ In the li<~uid phase, there is also convective heat exchange, but thi;~ was not modeled. In order nevertheless to simulate the temperature homogenization on the basis of the convective mixing, instead the thermal conductivity was increased by a fa<:tor of 100 compared to the solid phase. The various water coo=ing operations in the areas of the primary and secondary coo~_ing zones represent important boundary conditions. The temperature range of possible surface temperatures is d~_vided into sections of various heat transfer types (st:able film evaporation, unstable area, burn-out point, et:c.) on the basis of a heat transfer model, since different approaches apply with regard to the heat transfer coefficient for these areas. In some of these areas, the heat transfer coefficient is also dependent on the materials value of: the surface of the cooling body, this applying, in the present case, in particular to highly oxidized surfaces, for which the materials values of scale are to be used.
The simul~~tion of the stack of slabs begins with the introduction of tree first slab into the holding pit.
Thereafter, every 60 seconds the next slab is stacked on top of the previous slab. The stacking operation ends when a cold slab is laid on top of the twelve slabs which have hitherto been stacked. The inherent weight of the cold slab reduces the curvature of t:he top hot slab.
_ g _ After the first slab has been introduced into the store, the corresponding elements of this slab are activated, and the finite element simulation for this slab takes place as early as in the holding pit. The second slab follows, and the elements of s7_ab two are activated. This procedure continues in a similar manner until the final, cold slab is introduced into the store. The simulation of the entire stack of slabs in the holding pit then begins. Here as well, the heat transfer coefficients between the slab surfaces and the environment form ~~ignificant boundary conditions. With the exception of the bottom support surface, heat transfer through air convection plus radiation is assumed for all surfaces of the stack of slabs.
The air convection is calculated using specific functions, since different heat transfer coefficients apply for the horizonta7_ and vertical surfaces. At high temperatures, there coefficients are still low compared to the heat transfer coefficients of radiation, but at low temperatures the convection coefficients become dominant.
Furthermore, the ambient temperature throughout the wider environment of thEe hall and the walls of the holding pit form part of the calcu7_ation. However, in a representative stack, these parameters c:an only be seen in a particular part of the solid angle, while in other parts of the solid angle there are adjacent stac~a, which are at a similar temperature.
The bottom horizontal surface of the stack is in contact with the pit floor. The pit floor itself could be included in the finite element calculation, but in a simplified version it is also possible to model the pit floor as a semi-infinite' body which remains constantly at its starting temperature, at which there is then a time-dependent heat transfer coef=f icient .
For given slab dimensions, it is then possible to determine the temperature profile over the cross section of the slab or the stack of slabs. To be reintegrated into the material flow between caster and rolling mill, the mean temperature of a :steel slab should lie between 500 and 600°C.
At the start of cooling, the first slab still has the temperature profile corresponding to when it leaves the caster. At the encL of the stacking operation, it is found that there is a me>re homogenous temperature distribution in the stack if the floor is appropriately well insulated. As a result of the cold slab being laid on top, the top slab in the stack loses a relatively large amount of heat in the first hour, and the bottom slab in the stack cools rapidly during a short initial period, until the floor acts as an insulator.
By linking a physical-mathematical model to the automation of a standard slab material flow, the method according to the invention makes it possible to control the individual slabs between continuous-casting installation and rolling mill in an economical and reliable manner. By carrying out control measurements on the surface of the slabs, including t:he values obtained through the calculation model, it is possuble to draw conclusions as to the amount of heat and the temperature profile of the slab in a simple manner, provided that the appropriate boundary conditions are included. In this way it is possible to determine, at any location between continuous-casting installation and rolling mill and, in particular, in storage yards, how much heat is associated with tree particular slab and what level of energy has to be supplied or dissipated in order to reach the temperature profiles which are optimum for the further process. The invention provides a design engineer with a means of designing the installation optimally, so that it is economical to produce and run.
In the first substep, the solidification of the slab in the caster is simulated in order to generate an entry temperature profile of the slabs in the holding pit which is close to reality. The material density, specific heat and thermal conductivity are temperature-dependent.
_ g _ In the li<~uid phase, there is also convective heat exchange, but thi;~ was not modeled. In order nevertheless to simulate the temperature homogenization on the basis of the convective mixing, instead the thermal conductivity was increased by a fa<:tor of 100 compared to the solid phase. The various water coo=ing operations in the areas of the primary and secondary coo~_ing zones represent important boundary conditions. The temperature range of possible surface temperatures is d~_vided into sections of various heat transfer types (st:able film evaporation, unstable area, burn-out point, et:c.) on the basis of a heat transfer model, since different approaches apply with regard to the heat transfer coefficient for these areas. In some of these areas, the heat transfer coefficient is also dependent on the materials value of: the surface of the cooling body, this applying, in the present case, in particular to highly oxidized surfaces, for which the materials values of scale are to be used.
The simul~~tion of the stack of slabs begins with the introduction of tree first slab into the holding pit.
Thereafter, every 60 seconds the next slab is stacked on top of the previous slab. The stacking operation ends when a cold slab is laid on top of the twelve slabs which have hitherto been stacked. The inherent weight of the cold slab reduces the curvature of t:he top hot slab.
_ g _ After the first slab has been introduced into the store, the corresponding elements of this slab are activated, and the finite element simulation for this slab takes place as early as in the holding pit. The second slab follows, and the elements of s7_ab two are activated. This procedure continues in a similar manner until the final, cold slab is introduced into the store. The simulation of the entire stack of slabs in the holding pit then begins. Here as well, the heat transfer coefficients between the slab surfaces and the environment form ~~ignificant boundary conditions. With the exception of the bottom support surface, heat transfer through air convection plus radiation is assumed for all surfaces of the stack of slabs.
The air convection is calculated using specific functions, since different heat transfer coefficients apply for the horizonta7_ and vertical surfaces. At high temperatures, there coefficients are still low compared to the heat transfer coefficients of radiation, but at low temperatures the convection coefficients become dominant.
Furthermore, the ambient temperature throughout the wider environment of thEe hall and the walls of the holding pit form part of the calcu7_ation. However, in a representative stack, these parameters c:an only be seen in a particular part of the solid angle, while in other parts of the solid angle there are adjacent stac~a, which are at a similar temperature.
The bottom horizontal surface of the stack is in contact with the pit floor. The pit floor itself could be included in the finite element calculation, but in a simplified version it is also possible to model the pit floor as a semi-infinite' body which remains constantly at its starting temperature, at which there is then a time-dependent heat transfer coef=f icient .
For given slab dimensions, it is then possible to determine the temperature profile over the cross section of the slab or the stack of slabs. To be reintegrated into the material flow between caster and rolling mill, the mean temperature of a :steel slab should lie between 500 and 600°C.
At the start of cooling, the first slab still has the temperature profile corresponding to when it leaves the caster. At the encL of the stacking operation, it is found that there is a me>re homogenous temperature distribution in the stack if the floor is appropriately well insulated. As a result of the cold slab being laid on top, the top slab in the stack loses a relatively large amount of heat in the first hour, and the bottom slab in the stack cools rapidly during a short initial period, until the floor acts as an insulator.
By linking a physical-mathematical model to the automation of a standard slab material flow, the method according to the invention makes it possible to control the individual slabs between continuous-casting installation and rolling mill in an economical and reliable manner. By carrying out control measurements on the surface of the slabs, including t:he values obtained through the calculation model, it is possuble to draw conclusions as to the amount of heat and the temperature profile of the slab in a simple manner, provided that the appropriate boundary conditions are included. In this way it is possible to determine, at any location between continuous-casting installation and rolling mill and, in particular, in storage yards, how much heat is associated with tree particular slab and what level of energy has to be supplied or dissipated in order to reach the temperature profiles which are optimum for the further process. The invention provides a design engineer with a means of designing the installation optimally, so that it is economical to produce and run.
Claims (4)
1. A method for determining and controlling the material flow of continuous-cast slabs, in particular steel slabs, by monitoring and optimizing the temperature on their transport path between the continuous-casting installation and the rolling mill, wherein, to determine the amount of heat and the temperature profile of the slab, starting from the known temperature of the liquid phase at the mold exit of the continuous-casting installation and given knowledge of the physical parameters of the slab, the convective mixing of the amount of heat contained in the slab and the time-dependent heat loss from the inhomogeneously cooling slab to the surrounding medium are calculated by means of a mathematical-physical model, and the result of the calculation, if appropriate together with the measured surface temperature of the slab, is used to control the material flow in an existing slab-monitoring system.
2. The method for determining and controlling the material flow of continuous-cast slabs as claimed in claim 1, wherein the two-dimensional finite element method, the finite difference method or software using formulae derived from off-line studies are used to calculate the mathematical-physical model.
3. The method for determining and controlling the material flow of continuous-cast slabs as claimed in claims 1 and 2, wherein the physical parameters of the slab used are the temperature-dependent materials values, such as density p, the specific heat c p, the thermal conductivity .lambda. and scale properties.
4. The method for determining and controlling the material flow of continuous-cast slabs as claimed in claims 1 to 3, wherein the results of the calculation and the measured surface temperature of the slab are linked to automation of the material flow in the slab-monitoring system.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19744815A DE19744815C1 (en) | 1997-10-02 | 1997-10-02 | Method for determining and controlling material flow during continuous casting of slabs |
| DE19744815.1 | 1997-10-02 | ||
| PCT/DE1998/002915 WO1999018246A1 (en) | 1997-10-02 | 1998-09-22 | Method for determining and controlling material flux of continuous cast slabs |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2305401A1 true CA2305401A1 (en) | 1999-04-15 |
Family
ID=7845173
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002305401A Abandoned CA2305401A1 (en) | 1997-10-02 | 1998-09-22 | Method for determining and controlling material flux of continuous cast slabs |
Country Status (10)
| Country | Link |
|---|---|
| EP (1) | EP1019550A1 (en) |
| JP (1) | JP2001519474A (en) |
| KR (1) | KR20010072534A (en) |
| CN (1) | CN1094983C (en) |
| AU (1) | AU1432899A (en) |
| BR (1) | BR9812707A (en) |
| CA (1) | CA2305401A1 (en) |
| DE (1) | DE19744815C1 (en) |
| TW (1) | TW409083B (en) |
| WO (1) | WO1999018246A1 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100372950C (en) * | 2004-05-28 | 2008-03-05 | 上海宝信软件股份有限公司 | Process for controlling temperature of strip steel |
| CN100371097C (en) * | 2005-05-26 | 2008-02-27 | 上海宝信软件股份有限公司 | Control method of multiple material flow tracing |
| DE102011077322A1 (en) * | 2011-06-09 | 2012-12-13 | Sms Siemag Ag | Process for processing a continuously cast material |
| CN102393722B (en) * | 2011-11-14 | 2013-01-09 | 北京首钢自动化信息技术有限公司 | Monitoring method used for information management of materials in steel rolling mill |
| CN102416456B (en) * | 2011-12-14 | 2013-12-04 | 武汉钢铁(集团)公司 | Secondary cooling control system for continuous casting of plate blank and method |
| US9716399B2 (en) * | 2014-05-07 | 2017-07-25 | Fairchild Korea Semiconductor Ltd. | Vehicle charger |
| ES2879913T3 (en) | 2014-11-04 | 2021-11-23 | Primetals Tech Italy S R L | Method to minimize the overall production cost of long metal products |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3901582A1 (en) * | 1989-01-20 | 1990-08-02 | Schloemann Siemag Ag | Continuous casting plant |
| DE19508476A1 (en) * | 1995-03-09 | 1996-09-12 | Siemens Ag | Control system for a plant in the basic material or processing industry or similar |
| DE19545101C2 (en) * | 1995-12-04 | 2001-10-04 | Siemag Transplan Gmbh | Method and device for cooling metallurgical and rolling mill products |
| DE19603233C1 (en) * | 1996-01-30 | 1997-03-13 | Wick Hans Joachim Dr Ing | Determining product temperature profiles in metallurgical production processes |
-
1997
- 1997-10-02 DE DE19744815A patent/DE19744815C1/en not_active Revoked
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1998
- 1998-09-15 TW TW087115371A patent/TW409083B/en active
- 1998-09-22 WO PCT/DE1998/002915 patent/WO1999018246A1/en not_active Application Discontinuation
- 1998-09-22 CN CN98809770A patent/CN1094983C/en not_active Expired - Fee Related
- 1998-09-22 KR KR1020007003548A patent/KR20010072534A/en not_active Application Discontinuation
- 1998-09-22 CA CA002305401A patent/CA2305401A1/en not_active Abandoned
- 1998-09-22 BR BR9812707-1A patent/BR9812707A/en not_active Application Discontinuation
- 1998-09-22 AU AU14328/99A patent/AU1432899A/en not_active Abandoned
- 1998-09-22 EP EP98958181A patent/EP1019550A1/en not_active Ceased
- 1998-09-22 JP JP2000515037A patent/JP2001519474A/en active Pending
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|---|---|
| JP2001519474A (en) | 2001-10-23 |
| AU1432899A (en) | 1999-04-27 |
| DE19744815C1 (en) | 1999-03-11 |
| CN1094983C (en) | 2002-11-27 |
| BR9812707A (en) | 2000-08-22 |
| WO1999018246A1 (en) | 1999-04-15 |
| KR20010072534A (en) | 2001-07-31 |
| TW409083B (en) | 2000-10-21 |
| EP1019550A1 (en) | 2000-07-19 |
| CN1272887A (en) | 2000-11-08 |
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