EP3733323B1 - Procédé et installation de coulée en continu d'une barre de coulée - Google Patents

Procédé et installation de coulée en continu d'une barre de coulée Download PDF

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Publication number
EP3733323B1
EP3733323B1 EP20172396.2A EP20172396A EP3733323B1 EP 3733323 B1 EP3733323 B1 EP 3733323B1 EP 20172396 A EP20172396 A EP 20172396A EP 3733323 B1 EP3733323 B1 EP 3733323B1
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Prior art keywords
casting
software
cast
liquid phase
target
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EP20172396.2A
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German (de)
English (en)
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EP3733323A1 (fr
Inventor
Uwe Plociennik
Thomas Heimann
Wilfried Klos
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SMS Group GmbH
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SMS Group GmbH
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    • 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
    • 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
    • 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
    • B22D11/18—Controlling or regulating processes or operations for pouring
    • B22D11/188—Controlling or regulating processes or operations for pouring responsive to thickness of solidified shell

Definitions

  • the invention relates to a method for casting a cast strand according to the preamble of claim 1, and to a continuous casting plant according to the preamble of claim 11.
  • the operation of the secondary cooling of a continuous casting plant is usually carried out with spray or cooling water, whereby the amount of water that is applied to the surfaces of the cast strand is set using target temperature curves.
  • target temperature curves can vary depending on the material to be cast and, for example, depending on certain cooling zones of the supporting strand guide and/or the casting speed.
  • a target temperature curve determines the target values for the surface temperature to be achieved by the strand within the supporting strand guide, e.g. at the end of individual cooling zones that are part of this supporting strand guide.
  • the spray water quantities of the secondary cooling are regulated so that these target values are achieved.
  • Position control in relation to the sump tip of a cast strand using secondary cooling has the disadvantage that if there is a major change in the casting temperature, it is necessary to either greatly reduce or greatly increase the amount of water. If the amount of water is greatly reduced, there is a risk of bulging. On the other hand, if the amount of water is greatly increased, there is a risk of surface cracks because the surface of the cast strand is cooled (too) much.
  • a further disadvantage is the heavy formation of scale that occurs as a result of the high temperatures and long residence times, which affects the surface temperature of the cast strand. This can distort a measurement of the surface temperature of the cast strand.
  • the device comprises a supporting strand guide in the form of a support roller frame, along the longitudinal extension of which (ie viewed in the casting direction of the cast strand) a plurality of hydraulic servo cylinders are arranged, with which an adjustment of support rollers or a soft reduction for the cast strand is possible.
  • EP 2 346 631 B1 are a method and a device for controlling the solidification of a cast strand in a continuous casting plant when starting the casting process known.
  • a continuous casting plant is equipped with a process computer on which a first software and a second software are installed.
  • the first software calculates in real time and, in a known manner, controls the casting process that is carried out with the continuous casting plant.
  • correction factors are initially generated during the initial phase of a new casting process or when parameters of the currently running casting process are changed on the basis of processing currently obtained data from the ongoing casting process and/or on the basis of data stored in a database, with the second software then using these correction factors to generate corrected target data for the casting process and transferring them to the first software.
  • the above-mentioned technology according to EP 2 346 631 B1 The above-mentioned technology according to EP 2 346 631 B1
  • the use of the second software is primarily used to determine a casting speed or corrected target data for this, so that after this data has been transferred to the first software and the first software has carried out the corresponding control, the position of the sump tip of the casting strand is set to the target or nominal position.
  • the corrected target data calculated by the second software are immediately adopted by the first software and are therefore immediately taken into account in the control carried out by the first software.
  • this type of operation of the second software only takes place at the time from which the casting process is fully represented with the data calculated in real time, so that the first software then controls the casting process exclusively with this data.
  • the invention is based on the object of creating a technology for the continuous casting of metals with which the position of the sump tip of a cast strand, in particular with a large casting thickness, can be held more reliably at a certain target position or in a certain target range of the supporting strand guide and a thickness of the cast strand produced is set using simple and inexpensive means and the soft reduction can take place in a certain range.
  • This object is achieved by a method having the features of claim 1 and by a device having the features of claim 11.
  • a method according to the present invention is used for casting a cast strand in a continuous casting plant equipped with a process computer and having at least one casting machine.
  • the process computer comprises at least a first software that calculates in real time and controls the casting process.
  • the process computer comprises a second additional software that calculates faster than in real time and thus has a calculation speed greater than the first software.
  • the second software calculates, on the one hand in association with a specific casting length and, on the other hand, depending on currently obtained process parameters from the ongoing casting process, in particular in the area of the mold and/or from at least one process parameter stored in a database, which position would currently exist for a sump tip of the cast strand according to the specific casting length along a supporting strand guide of the continuous casting plant.
  • the second software compares this calculated sump tip position with a target position or a target range for the sump tip and continuously calculates a casting speed correction value on the basis of this. Instead of the sump tip, control can also be based on a solidification fraction or on a strand shell distance.
  • the casting speed correction value calculated by the second software is transferred to the first software, whereby the first software regulates the sump position in real time using the casting speed and only takes into account the casting speed correction value calculated by the second software in relation to the specific casting length with a delay that results from a distance between the target position or the target range for the sump tip and the casting speed last set in real time.
  • a sump tip position of the cast strand is always found within a predetermined or selected range along the supporting strand guide or the sump tip of the cast strand is kept in this predetermined range. Furthermore, the calculation of the casting speed correction value is carried out by means of the second software on the basis that from all Positions along the casting length up to the position of the sump tip the current target speed is averaged.
  • the invention and the associated method are based on the essential finding that the second software runs continuously or performs calculations during the casting process.
  • the second software runs continuously in parallel to the actual speed control, which is carried out by the first software.
  • the second software can separately take into account the effects of disturbances such as casting temperature, heat dissipation in the mold and/or changes in the water flow temperatures (e.g. in the secondary cooling or the primary or mold cooling) and calculate corresponding casting speed correction values, which are then transferred to the first software.
  • it is important that the calculation speed for the second software is selected to be higher than for the first software.
  • the first software can regulate or adjust the sump length (i.e. the position of the sump tip of the cast strand) using the casting speed, which serves as the control variable, and taking into account the casting speed correction values calculated by the first software.
  • Another "trick" for the method according to the invention is that the casting speed correction values calculated by the second software, after they have been transferred or sent to the first software, are then not taken into account by the first software immediately, but only after a delay, i.e. with a time lag that depends on the currently set casting speed and the target position or the target range for the sump tip of the cast strand. It is precisely this delayed consideration of the casting speed correction values calculated by the second software by the first software that makes it possible to bring the position of the sump tip into the predetermined or selected area of the supporting strand guide, i.e. into the target range, or to keep it there.
  • the sump tip is preferably used as the controlled variable.
  • a defined solidification fraction in the middle of the strand which has a solid fraction fraction ⁇ 1, can be used as a control variable for the process according to the invention.
  • the strand shell spacing can also be used as a controlled variable for the method according to the invention.
  • the calculation speed for the second software is set higher than for the first software, it is possible to look "into the future" with regard to the casting process and its further course using the method according to the invention.
  • the following example illustrates this: If the first software, which controls the casting process in real time, has a calculation time of 20 minutes, for example, the same sequence of the casting process can be simulated or calculated using the second software in a much shorter time, e.g. in just 30 seconds. Accordingly, it is possible to gain knowledge about the further course of the casting process at a much earlier point in time using the calculation of the second software than using the calculation of the first software.
  • the feature "obtained” can be a setting or a measurement.
  • “obtained” process parameters in the sense of the present invention are those that have either been specifically set (possibly on the basis of a previous calculation) or obtained as a result of a measurement.
  • a temperature field is determined, preferably calculated, for the cast strand along its conveying direction within the supporting strand guide, so that the associated temperature is known for each calculated node point of the cast strand, namely at a specific point of the cast strand or the length of the system, in particular within the supporting strand guide and its Cooling segments. From this, an exact position of the sump tip for the casting strand can then be determined.
  • At least one process parameter of the casting process selected from the group of chemical composition of the material of the cast strand, current casting temperature, current casting speed, water flow temperature for secondary cooling, or water flow temperature for the mold primary cooling and/or set casting length is taken into account. This advantageously ensures that current values or parameters of the ongoing casting process and the type of metal processed in the process are included in the calculations by the second software or are taken into account accordingly by the second software.
  • the casting speed correction value is calculated by means of the second software on the basis of process parameters stored in the database and is used by the first software at the beginning of the casting process as a control variable for its regulation. This is particularly advantageous when starting the casting process at the beginning of a production process or following an interruption in operation.
  • the casting speed correction value is calculated by means of the second software depending on the currently obtained process parameters from the ongoing casting process. In this case, if there are deviations between the target and actual values in relation to the temperature of the cast strand during the casting process, this casting speed correction value is then used by the first software to regulate the casting speed of the casting process.
  • the second software as already explained, is permanently "running" or switched on during the ongoing casting process. This ensures that possible deviations that may occur during the ongoing casting process are responded to by the The casting speed correction values calculated by the second software, which are then transferred from the second software to the first software for controlling the real casting process, can be reacted to accordingly.
  • a reference position along the supporting strand guide between the bath level and the target position or the target area for the sump tip is selected.
  • all target speeds calculated by the second software are used one after the other.
  • a type of average value is formed with regard to the formation of the sump length, since the sump length is an integrative result of the history of the casting speeds.
  • the reference position can expediently be at a point on the supporting strand guide that is between 40% and 70% of the distance from the bath level to the target position of the sump tip. This reference position can preferably be at least 60% of the distance from the bath level to the target position of the sump tip.
  • the calculation of the casting speed correction value is carried out by means of the second software on the basis that the current target speed is averaged from all positions along the casting length up to the position of the sump tip is based on the meaning that all casting length positions that are currently in the supporting strand guide have been successively assigned a target speed by the second software over time or the calculations.
  • Such an assignment can be understood to mean that the calculation values of the second software, i.e. the casting speed correction values calculated by means of the second software, from the past period are used for the current determination of the target casting speed in the first software in order to control the position of the sump tip of the casting strand in the future period.
  • the current casting speed influences the strand cross-sections along the supporting strand guide at all positions from the casting level to the sump tip, it is expedient to all these target speeds e.g. in the form of an average value for determining the current target speed. Values that occur most frequently - regardless of which position they are assigned to - are represented more strongly by the average value than values that occur rarely (e.g. outliers).
  • the present invention also provides a continuous casting plant for casting a cast strand.
  • a continuous casting plant comprises a mold with a lower opening, which is formed on a lower side of the mold, a process computer with at least a first software that calculates in real time and controls the casting process, wherein the process computer comprises a second additional software that calculates faster than in real time, so that the calculation speed for the second software is thus greater than for the first software, and a supporting strand guide, which adjoins the lower opening of the mold, wherein the cast strand can be moved along the supporting strand guide.
  • adjustable support rollers or pairs of rollers are arranged along the supporting strand guide, with which a thickness reduction for the cast strand takes place.
  • the supporting strand guide has a selected area in which a sump tip of the cast strand is to be located, wherein support rollers or pairs of rollers that have a soft reduction adjustability are arranged exclusively in the selected area of the strand guide.
  • the "trick" of the above-mentioned continuous casting plant is that the support rollers or pairs of rollers that can be adjusted for soft reduction and are intended for supporting the strand guide are arranged exclusively in the selected area in which the sump tip of the cast strand is also to be located.
  • the target position for the sump tip of the cast strand is to be located in the said selected area of the supporting strand guide. In this way, it is possible to carry out a targeted soft reduction for the cast strand using the adjustable support rollers or pairs of rollers in the selected area of the supporting strand guide.
  • All other support rollers or pairs of rollers which - viewed in the conveying direction of the cast strand - are usually located upstream of the selected area, can thus be designed conventionally. namely without a soft reduction adjustment function. These conventional support rollers only follow the thermal shrinkage of the cast strand 100.
  • the support rollers or pairs of rollers are combined to form roller segments. This facilitates both the assembly and disassembly of the individual support rollers when they are installed or removed from the continuous casting plant, and also a possible joint control for the purpose of carrying out a desired soft reduction for the cast strand.
  • the above-mentioned method according to the invention is also suitable for operating a continuous casting plant according to the present invention, in the sense that the position of the sump tip of the cast strand is thereby brought specifically into the selected area of the supporting strand guide or - in the event of changes in the casting process - also held there.
  • the present invention is expediently used in the production of cast strands which - in the case of the production of slabs or similar products - have a casting thickness of at least 250 mm, more preferably even greater casting thicknesses (e.g. 300 mm, preferably 350 mm, or even 400 mm, or more).
  • Such products are also known under the name "thick slabs". Because the control or regulation of the casting process according to the invention has a direct effect on all sections of the cast strand along the supporting strand guide by changing or adjusting the casting speed, this means that the invention is also suitable for such "thick slabs" or comparable products.
  • the cast strand has a casting thickness or a diameter of at least 150 mm.
  • Fig.1 shows a simplified side view of the continuous casting plant 110 according to the invention.
  • the continuous casting plant 110 comprises a mold 112 which has a lower opening 113 and thus a vertical exit downwards.
  • Liquid metal e.g. steel or a steel alloy, is poured into the mold 112 up to a casting level or bath level 114.
  • the continuous casting plant 110 comprises a supporting strand guide 116 in the area of a secondary cooling system 130, which adjoins the lower opening 113 of the mold.
  • the supporting strand guide 116 is thus arranged immediately downstream of the mold 112.
  • a casting or metal strand 100 emerges downwards from the lower opening 113 of the mold 112 and is then moved or transported along the supporting strand guide 116 in a conveying direction F.
  • the secondary cooling 130 comprises individual cooling segments (not specified in more detail) along the supporting strand guide 116, through which the application of a cooling medium, in particular in the form of water, e.g. through spray nozzles, to both sides of the metal strand 100 is ensured in order to cool the metal strand 100 in a targeted manner.
  • These cooling segments are each fed with cooling liquid via lines (not shown) and are each equipped with spray nozzles. Accordingly, it is possible to apply cooling liquid to the surfaces of the metal strand 100, namely to its top and/or bottom, through the spray nozzles of the individual cooling segments.
  • the continuous casting plant 110 is a thick slab plant with which a cast strand 100 with a thickness of preferably 250 mm, or possibly even greater casting thicknesses, can be produced.
  • the continuous casting plant 110 comprises, for example, a total of one hundred and twenty pairs of support rollers, which are divided into twenty physical segments or cooling segments 1-20.
  • the crack-critical straightening area is located within the supporting strand guide 116 in the cooling or straightening segments with numbers 8 and 9, which can be equipped with their own control circuits for the coolant supply, so that the specified target temperatures can be achieved.
  • the continuous casting plant 110 comprises a control or regulating unit 122, which is connected via a signal path 124 to the cooling segments of the supporting strand guide 116, among others.
  • This signal path 124 can be wired or wireless, e.g. via a radio link or the like.
  • the control or regulation unit 122 comprises a process computer 123 on which a first software I and a second additional software II are installed. The meaning and functionality of these two software packages I, II are explained separately below.
  • the control or regulation unit 122 is connected to a data storage 126 in which the required process data for the continuous casting plant 110 are stored.
  • this data storage 126 forms a database.
  • Via an interface it is possible to enter or read individual process data PD into the data storage 126.
  • This input option is provided in the Fig.1 symbolized by an arrow with "PD".
  • the continuous casting plant 110 is equipped with at least one (not specified in more detail) temperature sensor, or a plurality of such sensors, which is or are arranged adjacent to the supporting strand guide 116.
  • the temperature of the metal strand 100 can be determined by means of such a sensor or a plurality of such sensors in order to compare, for example, the previously calculated temperature of the metal strand 100 with the measurement.
  • the temperature data of the sensor or sensors are first fed to a data acquisition unit 128 and from there sent to the control or regulating unit 122 via the signal path 124.
  • the data memory 126 stores variables or parameters on the basis of which target temperatures can be set or determined for the individual cooling segments along the supporting strand guide 116. These variables can include a first target temperature, a second target temperature and a predetermined distance from the casting level 114. These variables depend on a specific material or a specific group of materials from which the metal strand 100 is produced, and in any case are independent of a specific continuous casting plant.
  • control and regulation unit 122 can be used to determine the individual cooling segments along the strand guide 116 in the area of the secondary cooling 130 of a specific continuous casting plant, e.g. the continuous casting plant 110 of Fig.1 , target temperatures can be set or specified.
  • the continuous casting plant 110 comprises a selected or predetermined region 120 for the supporting strand guide 116 or along it, which corresponds, for example, to segments No. 17 and No. 18.
  • adjustable support rollers 118 are arranged in this selected region 120, each of which is present in pairs in the form of an upper support roller R1 and a lower support roller R2 opposite thereto.
  • each of the segments No. 17 and No. 18 consists of three such roller pairs R1, R2, wherein the associated support rollers 118 can be adjusted individually, i.e. in the direction of the cast strand 100 guided between the support rollers 118. By adjusting these support rollers, a soft reduction is carried out for the cast strand 100.
  • both the upper support roller R1 and the lower support roller R2 are expediently adjusted so that a thickness reduction is achieved for the cast strand 100 both on its upper side and on its lower side. This is particularly important for a metal strand 100 in the form of a slab with a comparatively large Casting thickness, ie ⁇ 250mm is particularly advantageous. By reducing the thickness on the top and bottom, the internal quality of the cast strand 100 can be improved.
  • the adjustable support rollers 118 By using a more powerful design of the adjustable support rollers 118, larger individual removals are possible for a metal strand 100 and/or the service life of the soft reduction unit (i.e. segments no. 17 and no. 18) can be extended. Furthermore, the removal steps can be individually graded.
  • the support rollers which have a soft reduction adjustment function, are arranged only in the segments No. 17 and No. 18, i.e. in accordance with the selected area 120. This means that with the support rollers 118, which are arranged in the selected area 120, a soft reduction can be carried out for the cast strand 100.
  • the remaining support roller segments No. 1-16 and No. 19-20 are conventionally designed and do not have such a soft reduction adjustment function. Instead, they can only be adjusted to follow the thickness reduction caused by thermal shrinkage. This allows the continuous casting plant 110 to be built more cost-effectively.
  • the selected or predetermined area 120 of the supporting strand guide 116 is to be seen in the context that the sump tip of the cast strand 100 should be located or positioned therein during operation of the continuous casting plant 110.
  • a target position or a target area for the sump tip of the cast strand 100 is located within this selected area 120. This makes it possible to specifically carry out a soft reduction for the cast strand 100 within the selected area 120 of the supporting strand guide 116, finally by adjusting the support rollers 118 as explained.
  • Fig.2 shows a flow chart to illustrate the "architecture" of the control or regulation unit 122.
  • the process computer 123 (cf. Fig.1 ) of this control or regulating unit 122, a first software I (also referred to as simulation model "regulation”) and a second software II (also referred to as simulation model "feedback control").
  • a first software I also referred to as simulation model "regulation”
  • a second software II also referred to as simulation model "feedback control”
  • control or regulating unit 122 is shown positioned in the middle and is also labeled "communication simulation models and casting process". This indicates that the control or regulating unit 122 is set up or has the appropriate means to enable data exchange from the second software II with the first software I.
  • these process parameters PD can be entered into the data memory 126 via an interface and from there via the signal path 124 to the processor of the control or regulation unit 122. Following this, these process data are then forwarded by the control or regulation unit 122 to both the first software I (simulation model "feed-forward control") and the second software II (simulation model "regulation").
  • the second software II also receives information from the control and regulation unit 122 regarding the respective process parameters for the current casting process.
  • the second software II While the casting process is running and is controlled by the first software I, the second software II is running permanently in the background. In this regard, it is particularly emphasized that the second software II calculates much faster than in real time, at least faster than the first software I. In other words, the calculation speed for the second software II is set higher than for the first software I.
  • a method according to the present invention works as follows:
  • the second software II calculates or simulates, on the one hand in association with a specific casting length ("x") and, on the other hand, depending on currently obtained process parameters from the ongoing casting process, in particular in the area of the mold 112 and/or from at least one process parameter stored in the database 126, which position would currently exist for a sump tip of the cast strand 100 according to the specific casting length along the supporting strand guide 116 of the continuous casting plant 110.
  • the second software II calculates the position of the solidification or a defined solidification portion either in the middle of the strand or at a predetermined distance between the strand shells much faster than in real time of the casting strand 100 on the loose and fixed side, with the control variable casting speed.
  • the second software II compares this calculated sump tip position with the selected area 120, or with the target position for the sump tip, and on this basis continuously calculates a pouring speed correction value (in Fig.2 also referred to as "optimal speed for the casting length x").
  • This casting speed correction value corresponds to a target casting speed and is assigned to a specific casting length of the cast strand 100, based on the current process parameters of the casting process, such as casting temperature, chemical composition of the cast metal, heat dissipation in the mold and changes in the water flow temperatures (secondary cooling, primary or mold cooling).
  • the actual control of the casting process is carried out by the first software I (simulation model "control") in real time.
  • the first software I receives the necessary information regarding the individual process parameters from the control or regulating unit 122.
  • the first software I also receives the casting speed correction values calculated by the second software II via the control or regulating unit 122, i.e. values for the target casting speed, each of which belongs to a relevant casting length.
  • the value for an associated target speed (meaning: target casting speed) is then sent back to the control or regulating unit 122 using the first software I and from there output to the relevant components of the continuous casting plant 110.
  • the first software I controls the sump position in real time using the casting speed for the casting process carried out with the continuous casting plant 110 and in doing so uses the casting speed correction value calculated by the second software II in association with the determined Casting length is only taken into account with a delay.
  • This delay is determined by a distance of the selected area 120 or a target position for the sump tip and the casting speed last set in real time. As a result, this ensures that a sump tip position of the cast strand 100 in the ongoing casting process is always within the selected area 120 along the supporting strand guide 116 or the sump tip of the cast strand 100 is held in this predetermined area 120.
  • the control according to the invention can be carried out, for example, with a PI controller or a controller with similar properties.
  • a PI controller or a controller with similar properties.
  • it is possible to use algorithms to search for zero points ( target position - actual position 0). Which controller or algorithm is selected for the zero point search can be parameterized.
  • a casting operation is required for the continuous casting plant 110 in accordance with Fig.1 set such that the position of the sump tip of the cast strand 100 should be within the selected area 120.
  • a correspondingly set casting speed and adapted cooling (primary and secondary cooling) of the cast strand 100 With a correspondingly set casting speed and adapted cooling (primary and secondary cooling) of the cast strand 100, its sump tip is then located within the selected area 120.
  • the target position for the sump tip of the casting strand 100 has a distance of 20 meters from the casting level 114, with the set casting speed being 1 m/min.
  • the casting temperature in the area of the mold 112 or the casting level 114 is 10° increases. Such a temperature increase can be induced by the use of a new ladle. According to a further assumption, this temperature increase takes place in the area of the mold 112 at a time t n . At this time t n , a casting length of N meters has already been cast, so that the new piece of the cast strand 100 is designated with the casting length "N".
  • the cast strand 100 Due to the higher casting temperature, the cast strand 100 has more heat, so that the calculated sump tip increases by approx. 1 meter. If the other process parameters, such as in particular the cooling of the cast strand 100 in the area of the secondary cooling 130, remained unchanged during the above-mentioned temperature increase and only the first software I was available to control the casting process, this would result in the position of the sump tip, in view of the above-mentioned increase in length of approx. 1 meter - seen in the conveying direction F of the cast strand 100 - moving downstream (ie in the representation of Fig.1 from left to right) and would thereby "run out" of the selected area 120.
  • the other process parameters such as in particular the cooling of the cast strand 100 in the area of the secondary cooling 130, remained unchanged during the above-mentioned temperature increase and only the first software I was available to control the casting process, this would result in the position of the sump tip, in view of the above-mentioned increase in length of approx
  • a corresponding casting speed correction value is calculated using the second software II.
  • the second software II calculates much faster than in real time, the new strand piece with the casting length "N" reaches the position of the previous solidification, i.e. 20 meters from the casting level 114, after just 30 seconds, for example, in the "pre-control" simulation model.
  • the simulation time with the first software I which calculates in real time, would have already increased or progressed by 20 minutes.
  • the casting speed correction value calculated by the second software II - initially in the model and theoretically - is used to calculate the casting speed for the cast strand.
  • 100 resulting casting speed in the present numerical example is reduced in such a way that the position of the sump tip for the casting length "N" is again within the selected range 120 and thus reaches its target position.
  • the first software I stores the casting speed correction value calculated by the second software II after receiving it.
  • An essential feature of the method according to the invention is that the first software I does not immediately reduce the real casting speed by the said casting speed correction value, but only after a time delay.
  • the current casting speed is already reduced by the first software I by the casting speed correction value calculated by the second software II.
  • a position of e.g. 5 meters in front of the current or last sump position of e.g. 20 meters corresponds - at a casting speed of 1 m/min - to a time period of 15 minutes that the new piece of the cast strand 100 with the casting length "N" has covered up to that point.
  • the time required for this example is therefore Delay with which the first software I adjusts or reduces the real casting speed, taking into account the casting speed correction value calculated by the second software II, is 15 minutes.
  • the sump length is reduced by half the value by which it had increased in the simulation of the second software II, i.e. by only 0.5 m, until the arrival of the warmer strand section, ie the new section of the cast strand 100 with the casting length "N".
  • the real sump length of the cast strand 100 also increases by about 1 meter.
  • the second software II uses the casting speed which is about half the distance between the bath level 114 and the target position for the sump tip (this corresponds to Fig.6 the casting length L).
  • the first software I can, using the casting speed correction value calculated by the second software II and taking into account the said delay, reduce the actual casting speed for the casting process in a control-technical manner such that the sump length of the cast strand 100 continues to be within the selected range 120 or remains therein.
  • the first software I and the second software II always receive the same process values or process parameters of the ongoing casting process.
  • the reduction in the actual casting speed mentioned is related to the fact that a temperature increase is assumed in the area of the mold 112. If, contrary to this example, the melting temperature in a ladle were to drop, this would result in the first software I increasing the actual casting speed of the casting process using a casting speed correction value calculated accordingly by the second software II, also while observing the time delay explained.
  • FIG.3 shows an example of a possible link between second software II and first software I for the purpose of controlling the casting speed in order to achieve a target sump length or a target position for the sump tip of the casting strand 100.
  • Fig.3 two diagrams in which the pouring speed (with a solid line) and the position of the sump length (with a dashed line) are plotted as a function of time.
  • the upper diagram refers to the second software II (or the simulation model "feedback control”).
  • the lower diagram refers to the first software I (or the simulation model "control").
  • the target sump length is shown with a dash-dotted line.
  • the hatched area within which the respective dash-dotted line runs indicates a target area for the target position of the sump tip of the cast strand 100.
  • this hatched target area for the sump tip is within the selected area 120 of the supporting strand guide 116.
  • a sump tip control would only register an increase in the casting temperature when the first strand cross-section with the higher temperature has reached the solidification point.
  • the resulting exceedance of the target position leads to a decreasing speed ramp through the PI control.
  • another strand piece must have traveled the distance from the casting level 114 to the sump tip. If the control is set too high, this will result in undesirable overshoots. If it is set lower, the correction takes correspondingly longer.
  • the control system can determine very quickly which target speed would be suitable for which strand length. Since this target speed is usually not the same for all strand positions, an algorithm calculates which casting speed overall delivers the smallest deviations from the target value. This is done either by selecting a reference position for which the target speed is determined, or the current target speed is averaged from all positions up to the sump tip (which is also the case in Fig.6 shown with three example casting lengths K, L and M).
  • the averaged target speed (ie an average value calculated from the target casting speeds determined by the second software II for different casting lengths) can then be adopted directly by the first software I as the target speed, taking into account the time delay explained above.
  • a PI control can also be used to superimpose the current deviation of the sump length from the target position in order to take the actual process history of all strand cross-sections into account separately.
  • FIG.4 a dash-dotted horizontal line marking the setpoint for the position of the sump tip of the casting strand 100.
  • the diagram of Fig.4 illustrates that when the casting temperature changes by up to 20 °C, the casting speed is controlled such that the calculated sump length agrees well with the target value for the position of the sump tip of the casting strand 100.
  • Fig.5 shows two diagrams, namely in the upper diagram a course of the pouring temperature as a function of time, and in the lower diagram the resulting position of the sump tip as a function of time.
  • the time axes in the upper and lower diagrams of Fig.5 are chosen to be consistent. This means that the course of the sump tip (shown in the lower diagram) results in response to the change in the pouring temperature (shown in the upper diagram).
  • the lower diagram of Fig.5 illustrates that - if significant fluctuations occur for the casting temperature - then the resulting position of the sump tip, which is set using the method according to the invention, has smaller deflections compared to the conventional curve and is significantly closer to the target value (indicated by an arrow to the left of the ordinate) for the sump tip of the cast strand 100.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)

Claims (16)

  1. Procédé de coulée d'un fil de coulée (100) dans une installation de coulée continue (110) équipée d'un ordinateur de processus (123) avec au moins une machine de coulée, l'ordinateur de processus (123) comprenant au moins un premier logiciel (I) qui calcule en temps réel et régule le processus de coulée, l'ordinateur de processus (123) comprenant un deuxième logiciel (II) supplémentaire qui calcule plus rapidement qu'en temps réel, de sorte que la vitesse de calcul pour le deuxième logiciel (II) soit supérieure à celle du premier logiciel (I),
    dans lequel le deuxième logiciel (II) calcule, d'une part en association avec une longueur de coulée déterminée (K; L; M), et d'autre part en fonction des paramètres de processus actuellement obtenus à partir du processus de coulée en cours, en particulier dans la zone de la lingotière (112), et/ou à partir d'au moins un paramètre de processus stocké dans une base de données, quelle position est actuellement en cause pour une pointe de bain du fil de coulée (100) selon la longueur de coulée déterminée (K; L; M) le long d'un guide-support de fil de coulée (116) de l'installation de coulée continue (110), le deuxième logiciel (II) comparant cette position de pointe de bain calculée avec une position cible ou une plage cible (120) pour la pointe de bain et calculant en continu sur cette base une valeur de correction de vitesse de coulée, caractérisé en ce que
    la valeur de correction de vitesse de coulée calculée par le deuxième logiciel (II) est transmise au premier logiciel (I), le premier logiciel (I) régulant la position du bain à l'aide de la vitesse de coulée en temps réel et prenant en compte la valeur de correction de vitesse de coulée calculée par le deuxième logiciel (II) en association avec la longueur de coulée déterminée seulement avec un retard qui résulte d'une distance de la position cible ou de la plage cible (120) pour la pointe de bain et de la dernière vitesse de coulée réglée en temps réel, de sorte qu'une position de pointe de bain du fil de coulée (100) dans le processus de coulée en cours se trouve toujours à l'intérieur d'une plage (120) prédéterminée ou sélectionnée le long du guide-support de fil de coulée (116), ou que la pointe de bain du fil de coulée (100) est maintenue dans cette plage (120) prédéterminée ou sélectionnée, et
    en ce que le calcul de la valeur de correction de vitesse de coulée à l'aide du deuxième logiciel (II) est basé sur le fait que la vitesse cible actuelle est moyennée à partir de toutes les positions (K; L; M) le long de la longueur de coulée jusqu'à la position de la pointe de bain.
  2. Procédé selon la revendication 1, caractérisé en ce que pour le calcul de la valeur de correction de la vitesse de coulée au moyen du deuxième logiciel (II), au moins un paramètre de processus du processus de coulée est pris en compte qui est choisi parmi le groupe comprenant la composition chimique du matériau du fil de coulée (100), la température de coulée actuelle, la vitesse de coulée actuelle, la température d'entrée de l'eau pour le refroidissement secondaire, ou la température d'entrée de l'eau pour le refroidissement primaire de la lingotière et/ou la longueur de coulée réglée.
  3. Procédé selon la revendication 1 ou 2, caractérisé en ce que la valeur de correction de la vitesse de coulée calculée au moyen du deuxième logiciel (II) est basée sur des paramètres de processus stockés dans la base de données et est utilisée par le premier logiciel (I) au début du processus de coulée comme grandeur de réglage pour sa régulation.
  4. Procédé selon l'une des revendications 1 à 3, caractérisé en ce que la valeur de correction de la vitesse de coulée est calculée au moyen du deuxième logiciel (II) en fonction des paramètres de processus (128) actuellement obtenus à partir du processus de coulée en cours, cette valeur de correction de la vitesse de coulée étant utilisée par le premier logiciel (I) pour régler la vitesse de coulée du processus de coulée dans le cas où, dans le cours du processus de coulée, il y a des écarts entre les valeurs cibles et les valeurs réelles en ce qui concerne la longueur du bain du fil de coulée (100).
  5. Procédé selon l'une des revendications précédentes, caractérisé en ce qu'une position de référence est choisie le long du guide-support de fil de coulée (116) entre le niveau du bain (114) et la position cible ou la plage cible (120) pour la pointe de bain, à partir de laquelle la valeur de correction de la vitesse de coulée est reprise.
  6. Procédé selon la revendication 5, caractérisé en ce que la position de référence se situe à un endroit du guide-support de fil de coulée (116) qui est entre 40% et 70% de la distance du niveau du bain (114) à la position cible de la pointe de bain, de préférence en ce que la position de référence est à au moins 60% de la distance du niveau du bain (114) à la position cible de la pointe de bain.
  7. Procédé selon l'une des revendications précédentes, caractérisé en ce qu'une fraction de solidification définie au milieu du fil de coulée, qui a une fraction solide < 1, est utilisée comme grandeur de réglage.
  8. Procédé selon l'une des revendications précédentes, caractérisé en ce qu'une distance entre coquille et fil de coulée est utilisée comme grandeur de réglage.
  9. Procédé selon l'une des revendications précédentes, caractérisé en ce qu'il est utilisé pour produire des brames, le fil de coulée (100) ayant une épaisseur de coulée d'au moins 250 mm, de préférence d'au moins 300 mm, de préférence encore d'au moins 350 mm, de préférence encore d'au moins 400 mm.
  10. Procédé selon l'une des revendications 1 à 8, caractérisé en ce qu'il est utilisé pour produire des produits longs, le fil de coulée (100) ayant une épaisseur de coulée ou un diamètre d'au moins 150 mm.
  11. Installation de coulée continue (110) pour la coulée d'un fil de coulée (100), comprenant
    une lingotière (112) avec une ouverture inférieure (113) qui est formée sur un côté inférieur de la lingotière (112),
    un ordinateur de processus (123) comprenant au moins un premier logiciel (I), qui calcule en temps réel et régule le processus de coulée, l'ordinateur de processus (123) comprenant un deuxième logiciel (II) supplémentaire, qui calcule plus rapidement qu'en temps réel, de sorte que la vitesse de calcul pour le deuxième logiciel (II) soit supérieure à celle du premier logiciel (I), et
    un guide-support de fil de coulée (116), qui est connecté à l'ouverture inférieure (113) de la lingotière (112), le fil de coulée (100) pouvant être déplacé le long du guide-support de fil de coulée (116),
    des rouleaux de support ou des paires de rouleaux (118) pouvant être ajustés étant disposés le long du guide-support de fil de coulée (116), avec lesquels une réduction d'épaisseur pour le fil de coulée (100) est effectuée,
    le guide-support de fil de coulée (116) ayant une zone (120) sélectionnée dans laquelle une pointe de bain du fil de coulée (100) doit se trouver, caractérisé en ce que
    les rouleaux de support ou les paires de rouleaux (118), qui ont une capacité d'ajustement de réduction douce, sont exclusivement disposés dans la zone (120) sélectionnée du guide de fil de coulée (116).
  12. Installation de coulée continue (110) selon la revendication 11, caractérisée en ce qu'une paire de rouleaux (118) est formée de rouleaux de support opposés (R1, R2), entre lesquels le fil de coulée (100) peut être passé, les rouleaux de support respectifs pouvant être ajustés individuellement dans la direction de l'autre rouleau de support respectif.
  13. Installation de coulée continue (110) selon la revendication 11 ou 12, caractérisée en ce que les rouleaux de support ou les paires de rouleaux (118) sont regroupés en segments de rouleaux (17; 18).
  14. Installation de coulée continue (110) selon l'une des revendications 11 à 13, caractérisée en ce qu'une position d'une pointe de bain du fil de coulée (100) peut être réglée en particulier par un procédé selon l'une des revendications 1 à 8, de sorte que la position de la pointe de bain se trouve à l'intérieur de la zone (120) sélectionnée du guide-support de fil de coulée (116).
  15. Installation de coulée continue (110) selon l'une des revendications 11 à 14, caractérisée en ce que la lingotière (112) et le guide-support de fil de coulée (116) sont conçus de telle manière qu'un fil de coulée (100) sous forme de produit long avec une épaisseur de coulée d'au moins 150 mm peut être produit.
  16. Installation de coulée continue (110) selon l'une des revendications 11 à 14, caractérisée en ce que la lingotière (112) et le guide-support de fil de coulée (116) sont conçus de telle manière qu'un fil de coulée (100) sous forme de fil de coulée avec une épaisseur de coulée d'au moins 250 mm, de préférence d'au moins 300 mm, de préférence encore d'au moins 350 mm, de préférence encore d'au moins 400 mm peut être produit.
EP20172396.2A 2019-05-02 2020-04-30 Procédé et installation de coulée en continu d'une barre de coulée Active EP3733323B1 (fr)

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EP4124400A1 (fr) * 2021-07-28 2023-02-01 Primetals Technologies Austria GmbH Procédé de détermination d'une probabilité de défaut d'une partie de produit coulé
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DE10255550B3 (de) * 2002-11-28 2004-01-22 Sms Demag Ag Verfahren und Einrichtung zum Stranggießen von Brammen-, Dünnbrammen-, Vorblock-, Vorprofil-, Knüppelsträngen und dgl. aus flüssigem Metall, insbesondere aus Stahlwerkstoff
EP2346631B1 (fr) 2008-11-04 2015-07-22 SMS Siemag Aktiengesellschaft Procédé et dispositif de commande de la solidification d'une barre de coulée dans une installation de coulée continue lors de la mise en marche du processus de coulée

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