EP2125257B1 - Method and lubricant application device for regulating the planarity and/or roughness of a metal strip - Google Patents

Description

The invention relates to a method and a lubricant application device for controlling the flatness and / or roughness of a metal strip in the outlet of a cold rolling mill by appropriately dosing the applied in the inlet of the cold rolling stand on the metal strip amount of at least one lubricant per unit time.

Such a method is, for example, in the non-prepublished German patent application DE 10 2005 042 020 A1 described.

The Japanese publication JP 59 11 82 11 concerns the control of the flatness of a metal strip. It teaches measuring the flatness at the exit of a rolling stand and distributing a lubricant application over the width of the metal strip so as to obtain a desired flatness at the exit of the rolling stand.

Based on this technical teaching, the invention has the object, a known method and a known lubricant application device for controlling the flatness and / or roughness of a metal strip in the outlet of a cold rolling stand to the effect that the quantity of cold-rolled metal strip in terms of its flatness and / or its roughness is further improved.

This object is achieved by the method claimed in claim 1. This is characterized in that the applied amount of the lubricant is metered in the form of a quantity distribution over the width of the metal strip per unit time in accordance with a determined deviation between an actual and a desired flatness distribution over the width of the Metal strip in the outlet of the cold rolling stand or a control deviation between an actual and a desired roughness distribution over the width of the metal strip in the outlet of the cold rolling stand or a combination of the two control deviations.

In contrast to the technical teaching of the introductory cited patent application in the present patent application, the application of a suitable amount of lubricant on the inlet side of the cold rolling mill is not a flat rate, but distributed over the width of the metal strip. In this way it is advantageously possible, for each section in the width direction of the metal strip, e.g. in the application area of a single nozzle, supply an individual amount of lubricant so as to set a predetermined target flatness in the respective width section.

The amount of the lubricant applied is in a range of 1 - 20 ml / min / 100 mm width of the metal strip. This amount is advantageously so small that it allows a targeted change in the coefficient of friction in the nip of the cold rolling mill in view of the desired target flatness or target roughness. The residual amount of lubricant remaining in the outlet on the metal strip is minimal; it is advantageously so small that it does not have to be disposed of separately.

The invention provides that advantageously the residual content of lubricant on the metal strip on the outlet side of the cold rolling mill is measured. On the one hand, this residual content should not fall below a predetermined lower threshold, because otherwise there is a risk of rust formation on the metal strip, because the lubricants typically used also generally have a rust-inhibiting effect. On the other hand, the residual content of lubricant should not exceed an upper threshold, because otherwise there is a risk of a lateral course of the metal strip on a rolling mill downstream of the cold rolling stand.

All desired values given in the context of the present invention are preferably based on empirical values from practice.

For carrying out the method according to the invention, it is important that only the lubricant is applied in exactly metered quantity on the inlet side becomes. An additional application of coolant in the nip on the inlet side of the cold rolling stand is not provided in the inventive method, because this would falsify the targeted adjustment of the coefficient of friction in the nip. A plot of coolant is therefore in the method according to the invention, if provided at all, then only on the outlet side of the cold rolling stand or inlet side such that no coolant enters the roll gap.

Advantageously, a plurality of lubricants each having different coefficients of friction varying in the roll gap are available. As an alternative to metering a lubricant or a lubricant mixture, an exact coefficient of friction in the rolling gap can then also be set by means of a correspondingly suitable mixing ratio of the various lubricants. Advantageously, a mixture of the individual lubricants takes place only within the individual nozzles of a nozzle beam; Thus, a very specific adjustment of the coefficient of friction in the roll gap for each width section of the metal strip is individually possible. In addition, then a separate disposal / storage of unused lubricant is possible.

The adjustment of the desired flatness or roughness on the metal strip is in the present invention expressly not a change in the size of the nip in the cold rolling mill; rather, the size of the nip remains constant during the entire processing time of the metal strip or is controlled by means of a separate control loop, which is not the subject of the present invention. In this case, for example, the difference between the speed of the metal strip in the inlet and in the outlet serves as a measure of the size of the roll gap or the decrease of the strip.

The above object of the invention is further achieved by a computer program, a data carrier with this computer program and a lubricant application device. The advantages of these solutions match the advantages mentioned above with reference to the inventive method.

Figur 1

ein Kaltwalzgerüst mit einem Düsenbalken;

Figur 2

die erfindungsgemäße Kaskadenregelung; und

Figur 3

eine Detaildarstellung eines Blockes der Kaskadenregelung

The description is a total of four figures attached, wherein

FIG. 1

a cold rolling stand with a nozzle bar;

FIG. 2

the cascade control according to the invention; and

FIG. 3

a detailed representation of a block of cascade control

illustrated.

The invention will be described in detail below with reference to the mentioned figures.

FIG. 1 shows a lubricant application device 100 for applying lubricant S1, S2, S3 on the surface of a metal strip 400 in the inlet of a cold rolling stand. The lubricant application device 100 comprises a nozzle beam 110-o with a plurality of nozzles 110-i with i = 1-I for applying the lubricant 200 on the top of the metal strip 400 and another nozzle bar 110-u, also with a plurality of nozzles, for Applying lubricant to the underside of the metal strip 400. Each individual nozzle is 100-i is individually adjustable or regulatable with regard to the amount of lubricant discharged by it.

In addition to the amount of lubricant dispensed, the respective lubricant composition is individually adjustable by means of a mixer 150 for each nozzle 110-i. If a plurality of lubricants S1, S2, S3, each having different friction coefficient variations in the nip, are available, then the mixer 100 allows a suitable one to be assembled Lubricant mixture of the available lubricants S1, S2 and S3 with a specific desired property in terms of the coefficient of friction in the nip.

The already mentioned with the help of the nozzles possible dosage of the applied amount of lubricant also allows complete shutdown of individual nozzles 110-i. This is particularly advantageous in the outer nozzle of the nozzle beam, because by their switching on or off an adaptation to the width of each rolled metal strip 400 can be made and in this way a waste of lubricant can be prevented.

FIG. 2 illustrates the method of the invention for controlling the flatness and / or the roughness of a metal strip 400 in the outlet of a cold rolling mill 300 in the form of a control scheme. The diagram shows that the metering of the amount of lubricant applied to the metal strip is effected in the form of a cascade control with an internal control circuit for the distribution of the applied quantity of lubricant in the width direction, wherein the target value for the quantity distribution desired MV by means of a superimposed control loop determined or specified.

The inner control loop comprises a set / actual value comparator 124, a flow regulator 126 and an actuator in the form of the lubricant application device 110, and a quantity detection device 115 for detecting the amount of lubricant applied to the metal strip 400 by the nozzle bar 110 before the strip enters the cold rolling stand 300 The quantity distribution Ist-MV over the width of the metal strip 400 thus detected as an actual quantity is compared in the comparator 124 with a predefined desired quantity distribution desired MV and the control deviation e- _MV resulting from this comparison is fed to the downstream quantity regulator 126 , The quantity regulator, preferably a proportional P controller, converts the received deviation e _MV into a suitable control signal for driving the nozzles 110-i of the nozzle beam 110. The flow regulator 126 is preferably made of I individual regulators, which are each assigned to a nozzle 110-i of the nozzle beam individually. These individual controllers can be linked together via a bus. The output signal of the quantity regulator 126 in the form of the actuating signal for the nozzle bar 110 then in turn comprises a plurality of i individual actuating signals for the individual nozzles 110-i. Of course, the detection of the quantity distribution and its regulation by means of the inner loop for the top and bottom of the metal strip 400 is separated.

With reference to the Figures 2 and 3 In the following, the calculation according to the invention of the desired quantity of desired MV applied to the metal strip of lubricant for the upper or lower side of the metal strip 400 will be explained in greater detail with the aid of the superimposed control loop.

The calculation takes place in the setpoint calculation device 122 on the basis of a predetermined desired flatness distribution setpoint PLV and / or a predetermined setpoint roughness distribution setpoint RHV. These two predefined set values are empirical values which are suitably specified in particular as a function of the material of the respective strip to be rolled. As in FIG. 3 can be seen, the target value for the flatness distribution target PLV is first compared in a first comparator 122-1 with an actual value actual PLV, which represents the flatness distribution of the metal strip 400 at the exit of the cold rolling mill 300. The actual value actual PLV for the flatness distribution in the width direction of the metal strip is determined by means of a flatness meter 130-1, z. B. in the form of a flatness measuring roll, measured. At the output of the comparator 122-1 is then the deviation planarity distribution e- _PLV . Similarly, the target value for the roughness distribution target RHV is compared with the associated actual value actual RHV at the outlet of the cold rolling stand 300 in a second comparator 122-2, so that then a control deviation roughness e _RHV at the output of the second comparator 122nd -2 is present. The actual value actual RHV for the roughness distribution in the width direction of the metal strip is measured by means of a roughness sensor device 130-2, for example in the form of an optical sensor. Depending on the wishes of the user / application, the control deviation flatness distribution and the control deviation roughness distribution can be individually weighted in the calculation of the target quantity distribution. For this purpose, the two control deviations are weighted individually in a weighting device 122-3 before they enter into the calculation of the soli quantity distribution within the computing device 122-4.

As in FIG. 3 can be seen, in addition to the two weighted control deviations and various parameters in the calculation of the target quantity distribution. These characteristics are on the one hand metal strip 400 specific characteristics P1 on the inlet side of the cold rolling stand 300. This is the one the belt speed on the inlet side (variable) and the width of the metal strip, the material or the alloy of the metal strip and its profiling , In contrast to the speed of the metal strip on the inlet side, the three parameters mentioned below are to be regarded as constant in the context of the present invention. In addition to the metal strip-specific characteristics P1, rolling stand-specific parameters P2 are also included in the calculation of the setpoint quantity distribution, which in turn are all considered constant in the context of the present invention. These cold rolling stand-specific characteristics are the diameter of the work rolls, their roughness, their material and their crowning. As a third group, the outlet-side characteristics P3 should be mentioned, which comprises the flatness distribution of the metal strip, its roughness distribution, its bandwidth and its residual oil content per transport length unit, each measured on the outlet side of the cold rolling stand. As already mentioned, the flatness distribution and the roughness distribution are measured online as actual variables on the outlet side and fed individually to the comparator device 122-1 or 122-2 as variable process variables. In contrast, the bandwidth (assumed to be constant within the scope of the invention) and the residual oil content (measured online as a variable process variable) are fed to the arithmetic unit 122-4. The two outlet side Parameters of bandwidth and residual oil content are summarized below under the name P3 '.

As an intermediate result is thus to be noted that the setpoint distribution for the inner loop within the computing unit 122-4 in accordance with the inlet side characteristics P1, the cold rolling stand specific characteristics P2, the outlet side characteristics P3 'and determined in accordance with the weighted deviations for the flatness distribution and the roughness distribution becomes. It should be noted that of all the parameters mentioned only the speed of the metal strip on the inlet side, the two control deviations and the outlet side residual oil content per transport length unit of the metal strip are variable in time, while all other parameters are considered to be constant over time.

• a) Die am Auslauf des Kaltwalzgerüstes 300 festgestellte Rauheit des Metallbandes 400 ist weicht vom Sollwert ab.
  Dies kann z.B. bedeuten, dass die Ist-Rauheitsverteilung größer ist als der entsprechende vorgegebene Soll-Wert Soll-RHV, so dass die aus einem Vergleich dieser beiden Größen resultierende Regelabweichung Rauheitsverteilung e-_RHV negativ ist. In diesem Beispiel soll die Planheitsverteilung außer Acht bleiben, so dass die negative Regelabweichung bezüglich der Rauheit zu 100 % in die Recheneinrichtung 124-4 eingeht. Die Recheneinrichtung wird dann nach Maßgabe der Regelabweichung Rauheitsverteilung, sämtlicher konstanter Kenngrößen und nach Maßgabe des online ermittelten Restölgehaltes auf dem Metallband auf der Auslaufseite des Kaltwalzgerüstes 300 eine geeignete Soll-Mengenverteilung für den inneren Regelkreis vorgeben, so dass sich die Rauheitsverteilung im Auslauf des Kaltwalzgerüstes möglichst kurzfristig wieder auf das Niveau der Soll-Rauheitsverteilung einpegelt.
  Allgemein lässt sich festhalten, dass die Recheneinheit 122-4 bei zu großer Rauheit die Soll-Mengenverteilung und damit die einlaufseitig aufgetragene Menge an Schmiermittel nach Maßgabe der negativen Regelabweichung Rauheit verändern wird, um kurzfristig wieder eine Angleichung der gemessenen Rauheitsverteilung auf der Auslaufseite an die vorgegebene Rauheitsverteilung zu erzielen.
  In welcher Weise die Rauheit durch die Schmiermittelmenge und/oder Schmiermittelart beeinflusst wird, hängt von den allgemeinen Prozessbedingungen des Walzfalls ab, und wird vorteilhafterweise durch ein Prozessmodell berechnet.
• b) Die Planheitsverteilung auf der Auslaufseite des Kaltwalzgerüstes ist weicht von der Soll-Planheitsverteilung ab.
  In welcher Weise die Bandzugsspannungsverteilung und damit die Planheitsverteilung durch die Schmiermittelmenge und/oder Schmiermittelart beeinflusst wird, hängt von den allgemeinen Prozessbedingungen des Walzfalls ab, und wird vorteilhafterweise durch ein Prozessmodell berechnet.

The method according to the invention will now be described by way of example in some cases:

• a) The roughness of the metal strip 400 ascertained at the outlet of the cold rolling stand 300 differs from the nominal value.
  This may mean, for example, that the actual roughness distribution is greater than the corresponding predefined setpoint value target RHV, so that the control deviation roughness distribution e _RHV resulting from a comparison of these two variables is negative. In this example, the planarity distribution should be disregarded, so that the negative deviation with respect to the roughness is 100% in the computing device 124-4. The computing device will then according to the control deviation roughness distribution, all constant characteristics and according to the online determined residual oil content on the metal strip on the outlet side of the cold rolling stand 300 specify a suitable target quantity distribution for the inner loop, so that the roughness distribution in Outlet of the cold rolling stand as soon as possible leveled back to the level of the target roughness distribution.
  In general, it can be stated that, if the roughness is too great, the arithmetic unit 122-4 will change the setpoint quantity distribution and thus the amount of lubricant applied on the inlet side in accordance with the negative control deviation roughness in order to reconcile the measured roughness distribution on the outlet side to the predefined one Roughness distribution to achieve.
  How the roughness is affected by the amount of lubricant and / or type of lubricant depends on the general process conditions of the rolling case, and is advantageously calculated by a process model.
• b) The flatness distribution on the outlet side of the cold rolling stand is different from the desired flatness distribution.
  The manner in which the strip tensile stress distribution and hence the flatness distribution is influenced by the lubricant quantity and / or lubricant type depends on the general process conditions of the rolling case, and is advantageously calculated by a process model.

The criteria roughness distribution and flatness distribution can not only be considered separately, but also in parallel and set to predetermined target values. For this purpose, it is necessary to adjust the amount of lubricant applied on the inlet side as a function of the two control deviations of the flatness distribution and the roughness distribution.

For each calculation of the target quantity distribution within the computing device 122-4, the current residual oil content is taken into account only insofar as that is checked within the computing unit 122-4, on the one hand the residual oil content does not exceed a predetermined upper threshold for the residual oil content and on the other hand does not fall below a predetermined lower threshold for the residual oil content. Compliance with the upper threshold value is important in order to avoid lateral running of the metal strip on a roller conveyor connected behind the cold rolling stand. Compliance with the lower threshold is required to prevent rusting on the metal strip.

For all applications, a respective desired change in the coefficient of friction in the roll gap is realized not only by a change in quantity but alternatively also by a change in the composition of the lubricant mixture from the available lubricant components S1, S2 and S3 etc. or by a combination of change in quantity and mixture change become.

Preferably, the invention finds application in the last framework of a multi-stand rolling train.

Claims (21)

1. Method of regulating the planarity of a metal strip (400) in the outlet of a cold-rolling stand (300) by suitable metering of the quantity, which is applied to the metal strip in the inlet of the cold-rolling stand, of at least one lubricant (200) in the form of a quantity distribution over the width of the metal strip (400) per unit of time, characterised in that the metering is carried out in accordance with an ascertained regulating difference (e-_RHV) between an actual and a target surface roughness distribution over the width of the metal strip (400) in the outlet of the cold-rolling stand (300).
2. Method according to claim 1, characterised in that the metering is additionally carried out in accordance with an ascertained regulating difference (e-_PLV) between an actual and a target planarity distribution over the width of the metal strip (400) in the outlet of the cold-rolling stand.
3. Method of regulating the surface roughness of a metal strip (400) in the outlet of a cold-rolling stand (300) by suitable metering of the quantity, which is applied to the metal strip in the inlet of the cold-rolling stand, of at least one lubricant (200) per unit of time, wherein the applied quantity of the lubricant (200) is metered in the form of a quantity distribution over the width of the metal strip (400) per unit of time in accordance with an ascertained regulating difference (e-_PLV) between an actual and a target planarity distribution over the width of the metal strip (400) in the outlet of the cold-rolling stand or a regulating difference (e-_RHV) between an actual and a target surface roughness distribution over the width of the metal strip (400) in the outlet of the cold-rolling stand (300) or a combination of the two regulating differences.
4. Method according to any one of the preceding claims, characterised in that the quantity of the applied lubricant (200) is varied in a range of 1 to 20 ml / minute / 100 mm width of the metal strip (400).
5. Method according to any one of the preceding claims, characterised in that the metering of the quantity is carried out in the form of a cascade regulation by an internal regulating circuit for the applied quantity distribution, wherein the target value for the quantity distribution (Soll-MV) is determined with the help of a superimposed regulating circuit on the basis of individual, multiple or all variables from the groups of inlet-side variables (P1), variables (P2) specific to the cold rolling stand and outlet-side variables (P3) in accordance with the ascertained regulating deviation (e-_PLV) between the actual and the target planarity distribution, the regulating difference (e-_RHV) between the actual and the target surface roughness distribution or a combination of the two regulating differences.
6. Method according to claim 5, characterised in that the group of inlet-side variables (P1) of the metal strip (400) comprises the speed thereof there, the width thereof there, the material thereof and the profiling thereof there.
7. Method according to claim 5 or 6, characterised in that the group of variables (P2) specific to the cold rolling stand comprises the working roll diameter, the working roll surface roughness, the material of the working rolls and the camber of the working rolls.
8. Method according to claim 5, 6 or 7, characterised in that the group of outlet-side variables (P3) of the metal strip (400) comprises the speed thereof there, the width thereof there, the residual content of lubricant there on the surface thereof per unit of length in transport direction, the planarity distribution thereof there in width direction and the surface distribution thereof there in width direction.
9. Method according to claim 8, characterised in that an upper threshold value and/or a lower threshold value for the permissible residual content of lubricant on the outlet side is or are predetermined.
10. Method according to any one of claims 5 to 7, characterised in that the actual planarity distribution and the actual surface roughness distribution are each preset to a suitable start value, for example to zero, at the start of the method for the first determination of the target value for the quantity distribution.
11. Method according to any one of the preceding claims, characterised in that the metal strip (400) is cooled only on the outlet side, but not on the inlet side of the cold-rolling stand.
12. Method according to any one of the preceding claims, characterised in that a plurality of lubricants (S1, S2, S3) with respectively different action in reducing the coefficient of friction in the rolling gap of the cold-rolling stand (300) is available and the metering of the quantity distribution of the lubricant (200), which is applied to the metal strip, per unit of time and over the width of the metal strip is carried out by mixing, which is appropriate with respect to a desired coefficient of friction in the rolling gap, of the available lubricants (S1, S2, S3) with one another and with air.
13. Method according to any one of the preceding claims, characterised in that the metal strip (400) is, for example, a steel strip or a non-ferrous NE metal strip, for example an aluminium strip.
14. Method according to any one of the preceding claims, characterised in that the size of the rolling gap of the cold-rolling stand is kept constant during the entire period of processing of the metal strip (400).
15. Method according to any one of the preceding claims, characterised in that the lubricant is applied in the inlet of the cold-rolling stand to the upper side and/or lower side of the metal strip and/or to at least one working roll of the cold-rolling stand.
16. Computer program with a program code for a control device (120) of a lubricant application device (100), characterised in that the program code is constructed for performing the method according to any one of claims 1 to 15.
17. Data carrier with a computer program according to claim 16.
18. Lubricant application device (100) comprising:

    containers (160) for at least one lubricant (S1, S2, S3);

    at least one nozzle bar (110) with a plurality of nozzles (110-i), wherein the nozzle bar is arranged on the inlet side of a cold-rolling stand (300) transversely to the transport direction of a metal strip (400) for metering the lubricant (S1, S2, S3) to the metal strip per unit of time; and

    a control device (120) for suitable control of the nozzles (110-i) of the nozzle bar (110) with respect to a desired planarity of the metal strip;

    characterised in that a

    a surface roughness sensor device (130-2) is provided on the outlet side for detecting the actual surface roughness distribution there over the width of the metal strip (400); and

    the control device (120) is constructed in co-operation with the nozzle bar (110) to meter the at least one lubricant (S1, S2, S3) in quantity distribution over the width of the metal strip (400) and per unit of time in accordance with a regulating difference (e-_RH) between the actual and a target surface roughness distribution over the width of the metal strip (400) in the outlet of the cold-rolling stand.
19. Lubricant application device (100) according to claim 18, characterised in that a planarity sensor device (130-1) is provided on the outlet side of the cold-rolling stand (300) for detecting the actual planarity distribution there over the width of the metal strip and the control device (120) is constructed to meter the lubricant with respect to the desired planarity additionally in accordance with an ascertained regulating difference (e-_PLV) between the actual and a target planarity distribution over the width of the metal strip in the outlet of the cold-rolling stand (300) with respect to a desired planarity of the metal strip.
20. Lubricant application device (100) comprising:

    containers (160) for at least one lubricant (S1, S2, S3);

    at least one nozzle bar (110) with a plurality of nozzles (110-i), wherein the nozzle bar is arranged on the inlet side of a cold-rolling stand (300) transversely to the transport direction of a metal strip (400) for metering the lubricant (S1, S2, S3) to the metal strip per unit of time; and

    a control device (120) for suitable control of the nozzles (110-i) of the nozzle bar (110) with respect to a desired surface roughness of the metal strip;

    wherein

    a planarity sensor device (130-1) is provided on the outlet side of the cold-rolling stand (300) for detecting the actual planarity distribution there over the width of the metal strip and/or a surface roughness sensor device (130-2) is provided on the outlet side for detecting the actual surface roughness distribution there over the width of the metal strip (400); and

    the control device (120) is constructed in co-operation with the nozzle bar (110) to meter the at least one lubricant (S1, S2, S3) in quantity distribution over the width of the metal strip (400) and per unit of time in accordance with an ascertained regulating difference (e-_PLV) between the actual and a target planarity distribution over the width of the metal strip in the outlet of the cold-rolling stand (300) or a regulating difference (e-_RH) between the actual and a target surface roughness distribution over the width of the metal strip (400) in the outlet of the cold-rolling stand or a combination of the two regulating differences.
21. Lubricant application device (100) according to any one of claims 18, 19 and 20, characterised in that the lubricant application device is constructed for performance of the method according to any one of claims 1 to 15.

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