EP3642372B1 - Method for operating an annealing surface - Google Patents

Description

The one in the EP patent EP 2 742 158 B1 The claimed regulation of the material properties of a metal strip to a desired target material property including a simulation of actual material properties of a metal strip with the help of a computer-aided model requires a lot of computing power and computing time. The regulation takes place through an interactive modification of process parameters, temperature and / or speed in such a way that the desired material properties for the metal strip result. The increased computing time is disadvantageous because it results in a reduction in the possible calculation cases or iteration steps.

The essay Yahiro K et al: "Development of strip temperature control system for a continuous annealing line", Plenary Session, Emerging Technologies, and Factory Automation. MAUI, Nov. 15-19, 1993 ; [ Proceedings of the International Conference on Industrial Electronics, Control, and Instrumentation (IECON)], New York, IEEE, Us, Vol. 1, Nov. 15, 1993 (1993-11-15, pp. 481-486, XP000451844 discloses a method for operating an annealing furnace for annealing a metal strip with the following steps: According to patent claim 1: presetting at least one desired target material property that a point or a section of the metal strip should have after passing through the annealing furnace; Providing at least one piece of information (E) about the metal strip in front of or in the annealing furnace; Calculating a target temperature distribution and / or a target speed of the metal strip in the annealing furnace with the aid of a computer-aided model as a function of the desired target material property and the information about the metal strip; and setting the target temperature distribution and / or the target speed of the metal strip in the annealing furnace with the aid of a furnace control as an actuator.

The essay by Vallee G et al: "Ligne de recuit tout asynchrone pour ugine gueugnon", Revue de Metallurgie - Cahiers d'Informations Techniques, Revue de Metallurgie. Paris, FR, Vol. 90, No. 6, June 1, 1993 / 1993-06-01), pages 843-847, XP000393745, ISSN: 0035-1563 discloses a method similar to the aforementioned Yahiro paper, but using the properties of the metal strip to be treated and the actual properties of the method in a model to determine the speed and temperature to be used for the furnace.

The US patent application US 5,673,368 A also discloses a method of operating an annealing furnace using a computerized model. According to the US patent application, this model is adapted in each case after a complete heat treatment cycle.

The essay by Smith MA et al: "Application of distributes control on UPI'S KM / CAL", Aise Steel Technology, Aise, Pittsburg, PA, US, Vol. 70, No. 6, June 1, 1993 (1993-06-01), pp. 17 -22, XP000387767, ISSN: 0021-1559 discloses a method for operating an annealing furnace for annealing a metal strip according to the preamble of claim 1.

The invention is based on the object of developing a known method for operating an annealing furnace for annealing a metal strip with a view to improving the product quality and increasing the output.

This object is achieved by the method claimed in claim 1.

The method claimed according to claim 1 represents a control, but not a regulation. In the context of this control, the calculation and specification of a target temperature distribution and / or a target speed of the metal strip in the annealing furnace takes place so that the metal strip has a Has desired target material property. The presence of this desired target material property is not monitored in the context of the method claimed in claim 1 - unlike in the case of a regulation; in particular takes place No comparison of the desired target material property with a measured actual material property of the metal strip behind the exit of the annealing line for the purpose of forming a material property control difference and there is no regulation of this control difference to zero.

Strictly speaking, the term “temperature distribution” relates to a section of the metal strip. In the context of the present description, however, the term “temperature distribution” also implies a singular temperature value at a specific point on the metal strip.

The term “annealing furnace” in the context of the present description includes not only heating devices but also the heating devices downstream cooling devices in the flow direction.

The calculation and specification of a target temperature distribution and / or a target speed of the metal strip in the annealing furnace is less computationally time-intensive than the simulation of material properties. In addition, there is no feedback of a process variable in the context of the claimed control. Overall, this makes it possible to increase the output.

The claimed method is designed to carry out a desired self-correction or self-adaptation. For this purpose, the actual material property of the metal strip is measured after it has passed through the annealing furnace, and a comparison temperature distribution and / or a comparison speed of the metal strip in the annealing furnace is determined with the aid of the computer-aided model of the annealing furnace as a function of the measured actual material property and information provided about the metal strip in front of or in the annealing furnace. The temperature distribution and / or the speed of the metal strip in the annealing furnace is then adapted to the previously determined comparison temperature distribution and / or the comparison speed by suitable adaptation of the computer-aided model.

In other words: As part of the self-correction or self-adaptation, the method according to claim 1 for specifying a temperature distribution and / or the speed of the metal strip in the annealing furnace is carried out with the only difference that the computer model instead of the target material property the actually measured material property of the metal strip after passing through the annealing furnace is supplied as an input variable. For a better conceptual differentiation, in this case the output variables of the computer-aided model are called comparison variables, here specifically the comparison temperature distribution and / or the comparison speed. The actual temperature distribution and / or the actual speed of the metal strip in the annealing furnace are recorded as actual values and compared with the previously calculated comparison values. This comparison can result in a non-zero deviation for the temperature distribution and / or for the speed of the metal strip in the annealing furnace. In an adaptation value calculation unit, at least one suitable adaptation value is then subsequently calculated on the basis of the said deviations. The computer-aided model is then subsequently adapted with the aid of the calculated adaptation value. The method according to the invention described above for operating an annealing furnace is then carried out for future metal strips, preferably with the adapted computer-aided model. This then results in optimized target temperature distributions and / or target speeds for the metal strip, which are set with the aid of a furnace control as an actuator in the annealing furnace.

According to an embodiment of the invention, the computerized model can e.g. B. work with an experience database or with a statistical model or with stored glow curves and can therefore be used for any type of steel. This model can be used immediately, especially with newly developed steel grades. In contrast to a physical model, which must first be implemented for each new type of steel, the statistical model used according to the invention is easier to generate.

According to a further preferred exemplary embodiment, the computer-aided model is not adapted while that metal strip is passing through by the annealing furnace, on the basis of whose measured or simulated actual material property the calculation of the at least one adaptation value or the adaptation of the computer-aided model was carried out. Instead, the adaptation takes place preferably only for metal strips to be glowed in the future.

In the context of the present description, the term "material property of the metal strip", regardless of whether it is desired or actual size, means, for example, the yield point, tensile strength, elongation at break or the uniform elongation of the metal strip after it has passed through the annealing furnace.

• die Haspeltemperatur,
• die Endwalztemperatur des Metallbandes beim Auslauf aus einer Fertigstraße,
• die Eingangstemperatur der Bramme, aus dem das Metallband hervorgeht, am Eingang einer Fertigwalzstraße,
• die Bandgeschwindigkeit des Metallbandes beim Auslauf aus dem letzten Gerüst - der Fertigwalzstraße,
• die Walzkraft in einem Dressiergerüst,
• die Walzkräfte beim Kaltwalzen,
• die Walzkräfte beim Warmwalzen,
• die Eingangstemperatur der Bramme in einem Vorgerüst vor der Fertigwalzstraße,
• den Kaltwalzgrad,
• die Zusammensetzung des Werkstoffs, insbesondere des Stahls des Metallbandes, weiter insbesondere dessen Kohlenstoffanteil und / oder
• die Richtkraft am Flattener vor der CGL / CAL

meinen.The term “information about the metal strip” includes, for example, its tensile strength and / or yield point in front of a continuous galvanizing line CGL, in front of a continuous annealing line CAL, in a pickling line or in front of a reel. The information can also

• the reel temperature,
• the final rolling temperature of the metal strip when it leaves a finishing train,
• the entry temperature of the slab from which the metal strip emerges at the entry of a finishing train,
• the strip speed of the metal strip when it leaves the last stand - the finishing train,
• the rolling force in a skin pass mill,
• the rolling forces during cold rolling,
• the rolling forces during hot rolling,
• the inlet temperature of the slab in a roughing stand before the finishing train,
• the degree of cold rolling,
• the composition of the material, in particular the steel of the metal strip, further in particular its carbon content and / or
• the straightening force on the flattener in front of the CGL / CAL

mean.

This list does not claim to be complete; rather, other or further information can also be fed to the computer-aided model according to the invention as input variables.

Further advantageous refinements of the method according to the invention are the subject of the dependent claims.

• Figur 1 das erfindungsgemäße Verfahren; und
• Figur 2 die erfindungsgemäße Adaption des computergestützten Modells veranschaulicht.

Two figures are attached to the description, wherein

• Figure 1 the method according to the invention; and
• Figure 2 illustrates the inventive adaptation of the computer-aided model.

The invention is described in detail below with reference to the figures mentioned in the form of exemplary embodiments. In all figures, the same technical elements are denoted by the same reference symbols.

Figure 1 illustrates the method according to the invention for operating an annealing furnace 200. In the annealing furnace 200, metal strip 100 is annealed while it passes through the annealing furnace in the direction of the arrow. The core element of the method according to the invention is the calculation of a target temperature distribution T _target and / or a target speed V _target for the metal strip in the annealing furnace. This calculation takes place with the aid of a computer-aided model 220 of the annealing furnace as a function of a predetermined desired material property ME _{Soll of} the metal strip and as a function of information E about the metal strip. The Information relate to properties of the metal strip before or in the annealing furnace 200 or they relate to information about previous processing steps in the production of the metal strip. With regard to a more extensive meaning of the terms “material property” and “information”, reference is made at this point to the definitions of these terms given above in the general part of the description.

After the setpoint temperature distribution T _setpoint and / or the setpoint speed V _{setpoint has} been calculated by the computer-aided model 220, the corresponding values are output to a furnace control 230 as an actuator and implemented or set by this in the annealing furnace 200. Said setting of the target temperature distribution and / or the target speed V _{Soll of} the metal strip in the annealing furnace takes place with the aim of converting the actual material property ME _{Ist of} the metal strip behind the annealing furnace into the predetermined desired material property ME _Soll , also behind the Annealing furnace.

The calculation of the target temperature distribution T _Soll and / or the target speed V _{Soll of} the metal strip in the annealing furnace takes place as long as at least one point or section of the metal strip to which the said target material property ME _{Soll of} the metal strip relates or in the annealing furnace.

When calculating the target temperature distribution T _Soll in the annealing furnace 200 and / or when calculating the target speed V _Soll at which the metal strip passes through the annealing furnace 200, the computer-aided model 220 can rely on an experience database, a statistical model and / or fall back on stored glow curves.

• Messen der Ist-Materialeigenschaft ME_Ist des Metallbandes 100 nach Durchlauf durch den Glühofen 200, siehe Figur 1. Die Messung erfolgt vorzugsweise an dem Punkt oder Abschnitt des Metallbandes, für den die gewünschte Soll-Materialeigenschaft vorgegeben wurde.
• Berechnen einer Vergleichstemperaturverteilung T_Vgl und / oder einer Vergleichsgeschwindigkeit V_Vgl des Metallbandes 100 in dem Glühofen mit Hilfe des computergestützten Modells 220 in Abhängigkeit der gemessenen Ist-Materialeigenschaft ME_Ist des Metallbandes 100 und in Abhängigkeit der bereitgestellten Informationen E über das Metallband vor oder in dem Glühofen 200.

In order to continuously improve the quality of the method according to the invention for operating the annealing furnace 200, the method according to the invention optionally provides an occasional adaptation of the computer-aided model 220, see Figure 2 . The method according to the invention provides the following sub-steps for this adaptation:

• Measuring the actual material property ME _{ist of} the metal strip 100 after passing through the annealing furnace 200, see FIG Figure 1 . The measurement is preferably carried out at the point or section of the metal strip for which the desired target material property was specified.
• Calculating a comparison temperature distribution T _Vgl and / or a comparison _{speed V Vgl of} the metal strip 100 in the annealing furnace with the aid of the computer-aided model 220 as a function of the measured actual material property ME _{Ist of} the metal strip 100 and as a function of the information E provided about the metal strip before or in the Annealing furnace 200.

The comparison _{temperature distribution T Vgl} and comparison _{speed V Vgl} are calculated with the same computer model 220 taking into account the same information E about the metal strip as the first input variable as the setpoint temperature distribution and the setpoint speed of the metal strip in the annealing furnace according to FIG Figure 1 . However, for the calculation of the comparison variables, the computer model 220 does not take into account the desired target material property ME _{target as the second input variable, but rather the actual material property ME actual of} the metal strip, which is actually measured behind the annealing furnace. The temperature distribution and / or the speed of the metal strip in the annealing furnace are then adapted to the calculated corresponding comparison variables, ie the comparison temperature distribution T _Vgl and / or the comparison speed V _Vgl by appropriately adapting the computer-aided model 220.

Specifically, said adaptation comprises the following sub-steps; please refer Figure 2 :
The actual temperature distribution T _Ist and / or the actual speed V _{Ist of} the metal strip 100 in the annealing furnace 200 is / are recorded by measurement; please refer Figures 1 and 2 . These measured variables are compared in a comparison device 250 with the previously calculated associated comparison variables; that is, if necessary, a temperature deviation ΔT and / or a speed deviation ΔV are determined: ΔT = T _Vgl - T _actual , ΔV = V _Vgl - V _actual .

At least one of these deviations is input into an adaptation value calculating device 240, which calculates at least one suitable adaptation value a for adapting or adapting the computer-aided model 220 from these input variables. The computer-aided model 220 is then adapted with this adaptation value. According to the invention, this adaptation of the computer model 220 does not take place while a metal strip is running through the annealing furnace, but preferably always only after a complete metal strip has run through. The adaptation of the computer-aided model 220 therefore only affects future metal strips. The adjustment to the comparison value is therefore extremely slow. Advantageously, the adaptation and the measured value acquisition carried out for this enable good documentation and thus also conclusive evidence of the production conditions in the past; this is valuable quality documentation for further processors.

After the adaptation of the computer model 220 has taken place, future calculations of the target temperature distribution T _target and / or the target speed V _{target of} the metal strip are carried out with the aid of the adapted computer-aided model. The annealing furnace 200 is then operated with the newly calculated target values for the temperature distribution or the speed distribution.

List of reference symbols

100

Metal band

200

Annealing furnace

220

computerized model

230

Furnace control as an actuator

240

Adaptation value calculation device

E.

Information about the metal band

Most of time

Actual material property of the metal strip

MESoll

Target material property of the metal strip

Tis

Actual temperature distribution of the metal strip in the annealing furnace

Toll

Target temperature distribution of the metal strip in the annealing furnace

TVgl

Comparative temperature distribution for the metal strip

VIst

Actual speed of the metal strip in the annealing furnace

VSoll

Target speed of the metal strip in the annealing furnace

Cf.

Comparison speed for the metal strip in the annealing furnace

ΔT

Temperature deviation

ΔV

Speed deviation

Claims (6)

1. Method of operating an annealing furnace (200) for annealing a metal strip, comprising the following steps:

   - predetermining at least one desired target material characteristic (ME_Soll), such as, for example, the yield point, the tensile strength, the elongation at fracture and/or the uniform elongation, which a point or section of the metal strip (100) is to have after transiting the annealing furnace (200);

   - providing at least one item of information (E) about the metal strip before or in the annealing furnace (200);

   - calculating a target temperature distribution (T_Soll) and/or a target speed (V_Soll) of the metal strip (100) in the annealing furnace (200) with the help of a computer-supported model (220) in dependence on the desired target material characteristic (ME_Soll) and the item of information (E) about the metal strip;
   and

   - setting the target temperature distribution (T_Soll) and/or the target speed (V_Soll) of the metal strip (100) in the annealing furnace (200) with the help of a furnace control (230) as setting element;

   characterised by
   measuring the actual material characteristic (ME_Ist) of the metal strip (100) after transit through the annealing furnace (200), preferably at the point or section of the metal strip for which the target material characteristic is predetermined;
   calculating a comparative temperature distribution (T_Vgl) and/or a comparative speed (V_Vgl) of the metal strip (100) in the annealing furnace (200) with the help of the computer supported model (220) in dependence on the measured actual material characteristic (ME_Ist) after the transit and the provided item of information (E) about the metal strip before or in the annealing furnace (200); and
   adapting the temperature distribution and/or the speed of the metal strip (100) in the annealing furnace (200) to the comparative temperature distribution (T_Vgl) and/or the comparative speed (V_Vgl) by suitable adaptation of the computer-supported model, wherein the adaptation of the computer-supported model is carried out only after transit of at least the entire metal strip, optionally also several metal strips, through the annealing furnace (200);
   characterised in that
   the step of adaptation of the computer-supported model comprises the following substeps:

   measuring an actual temperature distribution (T_Ist) and/or an actual speed (V_Ist) of the metal strip (100) in the annealing furnace (200);

   comparing the actual temperature distribution (T_Ist) with the calculated comparative temperature distribution (T_Vgl) and determining a temperature difference (ΔT);

   comparing the actual speed (V_Ist) of the metal strip (100) in the annealing furnace (200) with the comparative speed (V_Vgl) and determining a speed difference (ΔV);

   calculating at least one suitable adaptation value (a) for adaptation of the computer-supported model (220) on the basis of the temperature difference (ΔT) and/or the speed difference (ΔV);

   adapting the computer-supported model (220) on the basis of the adaptation value (a); and recalculation of the target temperature distribution (T_Soll) and/or the target speed (V_Soll) of a new metal strip (100) with the help of the adapted computer-supported model (220).
2. Method according to claim 1,
   characterised in that
   the calculation of the target temperature distribution and/or the target speed of the metal strip is carried out as long as the at least one point or section of the metal strip to which the desired target value characteristic (ME_Soll) of the metal strip relates is still in front of or in the annealing furnace (200).
3. Method according to claim 1 or 2,
   characterised in that
   for calculation of the target temperature distribution (T_Soll) and/or the target speed (V_Soll) the computer-supported model (220) has resort to an empirical databank, a statistical model or filed annealing plots.
4. Method according to claim 1,
   characterised in that
   the actual material characteristic of the metal strip is measured directly on-line or at a sample, which is removed from the metal strip, after the transit of the metal strip (100) through the annealing furnace.
5. Method according to claim 1,
   characterised by
   repetition of the steps according to any one of the preceding claims with the adapted computer-supported model for the annealing of a future metal strip (100).
6. Method according to any one of the preceding claims,
   characterised in that
   the items of information (E) about the metal strip (100) before or in the annealing furnace (200) are, for example:

   - the tensile strength and/or yield point thereof before a continuous galvanising line CGL, before a continuous annealing line CAL, in a pickling line or before a coiler,

   - the coiler temperature,

   - the final rolling temperature of the metal strip at the outlet of a finishing train,

   - the entry temperature of the slab, from which the metal strip is produced, at the inlet of a finishing rolling train,

   - the strip speed of the metal strip at the outlet from the last stand of the finishing rolling train,

   - the rolling force in a finishing stand,

   - the rolling forces during cold rolling,

   - the rolling forces during hot rolling,

   - the entry temperature of the slab into a roughing stand in front of the finishing rolling train,

   - the degree of cold rolling,

   - the composition of the material, particularly the steel of the metal strip, more particularly the carbon proportion thereof; and/or

   - the straightening force at the flattener in front of the CGL / CAL.

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