EP2477763B1 - Cold roller path with mass flow regulation on a roller frame - Google Patents

Description

The present invention relates to a control method for a cold rolling mill, which has a plurality of cold strip successively traversed stands, wherein metrologically an actual speed is detected, with which the cold strip from one of the rolling stands expires, further comprising a strip thickness is detected with which the cold strip from the expires rolling stand.

The present invention further relates to a control device for a cold rolling mill, which has a plurality of rolling mills passed through in succession by a cold strip, the control device being supplied with a metrologically detected actual speed with which the cold strip runs out of one of the rolling mills, wherein the control device further comprises a metrologically detected strip thickness , with which the cold strip runs out of the relevant rolling stand, is supplied.

The present invention further relates to a computer program having machine code which is directly executable by a controller of a multi-stand cold rolling mill and whose execution by the controller causes the control means to control the cold rolling mill according to a control method of the type described in the opening paragraph.

• wobei die Kaltwalzstraße mehrere von einem Kaltband nacheinander durchlaufene Walzgerüste aufweist,
• wobei die Kaltwalzstraße eine Geschwindigkeitserfassungseinrichtung aufweist, die einem der Walzgerüste nachgeordnet ist und mittels derer messtechnisch eine Istgeschwindigkeit erfasst wird, mit der das Kaltband aus einem der Walzgerüste ausläuft,
• wobei die Kaltwalzstraße eine Dickenerfassungseinrichtung aufweist, die dem betreffenden Walzgerüst nachgeordnet ist und mittels derer eine Banddicke erfasst wird, mit der das Kaltband aus dem betreffenden Walzgerüst ausläuft,
• wobei die Kaltwalzstraße eine Steuereinrichtung der eingangs beschriebenen Art aufweist, so dass die Kaltwalzstraße gemäß einem Regelverfahren der eingangs beschriebenen Art betrieben wird.

Finally, the present invention relates to a cold rolling mill,

• wherein the cold rolling mill has a plurality of rolling stands through which a cold strip passes in succession,
• wherein the cold rolling mill has a speed detecting device, which is arranged downstream of one of the rolling stands and by means of which a metrological Actual speed is detected, with which the cold strip runs out of one of the rolling stands,
• wherein the cold rolling train has a thickness detection device, which is arranged downstream of the respective rolling stand and by means of which a strip thickness is detected, with which the cold strip runs out of the respective rolling stand,
• wherein the cold rolling train has a control device of the type described above, so that the cold rolling mill is operated according to a control method of the type described above.

The above items are for example from the WO 2009/095323 A1 known.

In the WO 2009/095323 A1 The strip thicknesses in front of and behind the first mill stand of the cold rolling mill as well as the actual speed of the cold strip behind the first mill stand of the cold rolling mill are recorded. On the basis of these variables, the setpoint value for the roll circumferential speed of the first roll stand is tracked such that the mass flow through the first roll stand corresponds to a desired mass flow. At the same time, on the basis of the strip thickness and the strip speed in front of the first rolling stand of the cold rolling train, a strip feeding device (for example a reel or an S-roll set) upstream of the first rolling stand is likewise regulated to the desired mass flow. The doctrine of WO 2009/095323 A1 is based on the principle of impressing the target mass flow over the strip feed device in front of the first rolling stand of the cold rolling mill and adjusting the strip thickness behind the first rolling stand of the cold rolling line indirectly via the actual speed of the cold strip behind the first rolling stand of the cold rolling mill.

The from the WO 2009/095323 A1 known procedure leads to good results if the tape feeder can be controlled so that it actively affects the mass flow ("can memorize the target mass flow"). However, there are also cold rolling mills in which the tape feed Although it can passively follow a changed mass flow, it can not actively set the mass flow itself. An example of such a cold rolling train is a cold rolling mill in which the belt feeding device operates in tension controlled operation, ie adjusts the mass flow in accordance with the tension in the cold strip between the strip feeding device and the first rolling stand of the cold rolling mill.

The object of the present invention is to provide possibilities by means of which the mass flow can be set precisely in a simple manner even if the band feeding device arranged upstream of the first rolling stand can not actively set the mass flow.

The object is procedurally achieved by a control method having the features of claim 1. Advantageous embodiments of the control method according to the invention are the subject of the dependent claims 2 to 5.

• dass die erfasste Istgeschwindigkeit mit einer korrespondierenden Sollgeschwindigkeit verglichen wird und anhand des Vergleichs ein Sollwert für eine Walzenumfangsgeschwindigkeit des betreffenden walzgerüsts nachgeführt wird, so dass die Istgeschwindigkeit an die Sollgeschwindigkeit angeglichen wird,
• dass das betreffende Walzgerüst entsprechend dem nachgeführten Sollwert für die Walzenumfangsgeschwindigkeit des betreffenden Walzgerüsts angesteuert wird und
• dass ein Walzspalt des betreffenden Walzgerüsts anhand zumindest der erfassten Banddicke derart nachgeführt wird, dass das Produkt von Istgeschwindigkeit des Kaltbandes und Banddicke einem Sollmassenfluss entspricht.

According to the invention - in addition to the features mentioned above - provided

• in that the detected actual speed is compared with a corresponding set speed and, based on the comparison, a setpoint value for a roller circumferential speed of the relevant rolling stand is tracked so that the actual speed is adjusted to the set speed,
• that the rolling stand in question is driven in accordance with the tracked setpoint value for the circumferential roller speed of the respective rolling stand, and
• a roll nip of the relevant roll stand is tracked on the basis of at least the detected strip thickness such that the product of the actual speed of the cold strip and the strip thickness corresponds to a desired mass flow.

In a preferred embodiment of the control method according to the invention, it is provided that the setpoint value for the roll circumferential speed of the rolling stand in question is determined on the basis of the desired speed and a model-determined advance and that the tracking of the target value for the roller peripheral speed of the respective stand is realized by adapting the model by which the lead is determined on the basis of the comparison of the actual speed with the target speed , By means of this configuration, it can be achieved, in particular, that in the event that the detection of the actual speed is disturbed, an emergency operation can be maintained. Because in this case, only the adaptation of the model, by means of which the overfeed is determined, must be interrupted.

Of the three sizes actual speed of the cold strip, strip thickness and mass flow, one of the sizes is redundant, since the product of the actual speed and the strip thickness corresponds to the mass flow. Due to the fact that the actual speed is controlled directly in the context of the present invention, it is therefore possible that the rolling gap of the respective rolling mill is tracked exclusively on the basis of the detected strip thickness. In general, however, it leads to better results when the nip of the respective rolling mill is tracked by the product of the actual speed of the cold strip and strip thickness.

The control method according to the invention can in principle be used in any of the rolling stands of the cold rolling mill. It is also possible to use the control method according to the invention simultaneously in several rolling stands of the cold rolling mill. It is preferred that at least the rolling mill of the cold rolling train, which is first passed through by the cold strip, is regulated in accordance with the invention.

The object is also achieved by a device with the features of claim 6. Advantageous embodiments of the control device according to the invention are the subject of the dependent claims 7 to 10.

• die ihr zugeführte Istgeschwindigkeit mit einer korrespondierenden Sollgeschwindigkeit vergleicht und anhand des Vergleichs einen Sollwert für eine Walzenumfangsgeschwindigkeit des betreffenden Walzgerüsts nachführt, so dass die Istgeschwindigkeit an die Sollgeschwindigkeit angeglichen wird,
• das betreffende Walzgerüst entsprechend dem nachgeführten Sollwert für die Walzenumfangsgeschwindigkeit des betreffenden Walzgerüsts ansteuert und
• einen Walzspalt des betreffenden Walzgerüsts anhand zumindest der ihr zugeführten Banddicke derart nachführt, dass das Produkt von Istgeschwindigkeit des Kaltbandes und Banddicke einem Sollmassenfluss entspricht.

According to the invention it is provided that the control device - in addition to the features mentioned above -

• compares the actual speed supplied to it with a corresponding set speed and, on the basis of the comparison, tracks a setpoint value for a roller circumferential speed of the respective rolling stand, so that the actual speed is matched to the set speed;
• the respective rolling mill according to the tracking setpoint for the roller circumferential speed of the respective rolling stand controls and
• a rolling gap of the respective roll stand based on at least the strip thickness fed to it nachzuführen such that the product of actual speed of the cold strip and strip thickness corresponds to a desired mass flow.

The advantageous embodiments of the control device correspond in content to those of the control method. In addition, the control device can be designed as a software programmable control device.

The object is further achieved by a computer program of the type mentioned above, whose execution by the control device causes the control device controls the cold rolling train according to a control method according to the invention. The computer program can be stored on a data carrier in machine-readable form.

Finally, the object is achieved by a cold rolling train, in which - in addition to the features mentioned above - the control device is designed in accordance with the invention, so that the cold rolling train is operated according to a control method according to the invention.

FIG 1

schematisch eine Kaltwalzstraße,

FIG 2

eine mögliche Ausgestaltung der Geschwindigkeitsregelung und

FIG 3

eine bevorzugte Ausgestaltung einer Walzspaltregelung.

Further advantages and details will become apparent from the following description of exemplary embodiments in conjunction with the drawings. In a schematic representation:

FIG. 1

schematically a cold rolling mill,

FIG. 2

a possible embodiment of the cruise control and

FIG. 3

a preferred embodiment of a roll gap control.

According to FIG. 1 For example, a cold rolling mill for rolling a cold strip 1 has a plurality of rolling stands 2. The rolling stands 2 are passed through by the cold strip 1 in succession.

As far as below generally speaking only of the rolling stands 2 of the cold rolling mill, only the reference numeral 2 itself is used for the rolling stands 2. Partially, however, the reference numeral 2 - separated by a hyphen - a digit or letter n readjusted. In this case, "2-1" denotes the rolling mill 1 first passed through by the cold-rolled strip 1, "2-2" the rolling mill etc. next passed by the cold-rolled strip 1, etc. "2-n" denotes the rolling stand of the cold rolling line last passed by the cold strip 1. Further, the shorter notation will be referred to briefly as the first rolling stand, the second rolling stand, etc. up to and including the last rolling stand, because of the respective rolling stands 2-1, 2-2, etc.

The cold rolling mill is preceded by a strip feeding device 3, via which the cold strip 1 is fed to the first rolling stand 2-1. The tape feeder 3 is according to FIG. 1 designed as a rewinder.

At least one of the rolling stands 2 - as shown by FIG. 1 the first rolling stand 2-1 - a speed detection device 4 is arranged downstream. By means of the speed detection device 4 an actual speed v is detected by measurement, with which the cold strip 1 from the speed detection device 4 upstream rolling stand 2 (here: the first rolling stand 2-1) expires. The detected actual speed v is - with the exception of unavoidable measuring errors - directly with the actual speed the cold strip 1 identical. The actual speed v is, in particular, not a roller peripheral speed vU of the upstream rolling stand 2, that is to say a size that is linked to the actual speed of the cold strip 1 only via an overfeed. Also, it is not a roller peripheral speed vU 'of a downstream roll stand 2, according to FIG. 1 Rolling mill 2-2.

The design of the speed detection device 4 can be made as needed. For example, as shown in FIG FIG. 1 a role are employed on the cold strip 1, which runs along with the cold strip 1 and whose speed is detected, for example by means of a pulser. Optical measuring methods, in particular laser measuring methods, are also known.

The same rolling mill 2-1 is further downstream of a thickness detection device 5. By means of the thickness detection device 5, a strip thickness d is measured, with which the cold strip 1 from the thickness detection device 5 upstream rolling stand 2 (here: the first rolling stand 2-1) expires.

The detection of the actual speed v is possible virtually without delay. The exact arrangement of the speed detection device 4 is therefore of secondary importance. The detection of the strip thickness d, however, can only be delayed, since the strip thickness d can only be detected locally at the location of the thickness detection device 5 and from the expiry of the cold strip 1 from the upstream rolling stand 2-1 passes until reaching the thickness detection device 5, a transport time. Preferably, therefore, the thickness detection device 5 is arranged as close as possible to the upstream rolling stand 2-1 in order to keep the transport time as low as possible and therefore to achieve the highest possible dynamics.

The detected actual speed v and the detected strip thickness d are fed to a control device 6 of the cold rolling train. The control device 6 evaluates the actual speed v supplied to it and the strip thickness d fed to it and controls the respective rolling stand 2 - according to the embodiment of FIG FIG. 1 the first rolling stand 2-1 - accordingly. This is done as follows:

The control device 6 compares the detected actual speed v of the cold strip 1 with a corresponding desired speed v *, that is, with the speed at which the cold strip 1 is to run out of the upstream rolling stand 2-1. Based on the comparison, the control device 6 performs a desired value vU * for the circumferential roll speed vU of the respective rolling stand 2-1, so that the actual speed v of the cold strip 1 is adjusted to the desired speed v *. Corresponding to the tracked nominal value vU * for the roller circumferential speed vU, the control device 6 controls the relevant rolling stand 2-1.

In order to readjust the setpoint value vU * for the circumferential roller speed vU, the control device 6 can correspond to FIG FIG. 1 implement an underlying controller structure in the simplest case: an external setpoint-actual controller determines the setpoint vU * for the roller peripheral speed vU based on the difference between the actual speed v of the cold strip 1 and the corresponding setpoint speed v *, an internal controller regulates the difference of the setpoint vU * for the roller peripheral speed vU and the roller peripheral speed vU itself, the roller circumferential speed vU. Preferably, however, the procedure is different. The preferred procedure is described below in connection with FIG. 2 explained in more detail.

According to FIG. 2 there is a roll gap model 7, by means of which a lead a is determined on the basis of framework and strip sizes, that is to say a factor which determines the setpoint speed v * of the cold-rolled strip 1 and the setpoint value vU * for the circumferential roll speed vU are related, $$a=v*/\mathit{vU}*$$

The reciprocal of the overfeed a is fed to a multiplier 8, which determines the corresponding desired value vU * for the circumferential roll speed vU on the basis of the setpoint speed v * of the cold strip 1.

According to FIG. 2 is determined on the basis of the comparison of target speed v * and actual speed v of the cold strip 1 - in particular on the basis of the difference - a correction factor k, based on which the roll gap model 7 is adapted. Due to the adaptation of the roll gap model 7, the overfeed a determined by the roll gap model 7 changes (inter alia). The tracking of the target value vU * for the circumferential roll speed vU is performed according to FIG. 2 Thus realized indirectly, namely the fact that the roll gap model 7 on the basis of the comparison of the actual speed v of the cold strip 1 with the target speed v * is adapted.

The control device 6 further performs, by means of a corresponding manipulated variable s *, a rolling gap s of the respective rolling stand 2-1 in such a way that the product of the actual speed v of the cold strip 1 and the strip thickness d corresponds to a desired mass flow M *. It is according to the representation of FIG. 1 it is possible for the control device 6 to track the roll gap s exclusively on the basis of the strip thickness d (and a corresponding desired thickness d *). Because due to the regulation of the actual speed v of the cold strip 1 to the desired speed v * also this type of tracking results in a defined mass flow. Preferably, however, according to FIG. 3 in a multiplier 9, the product of the actual speed v of the cold strip 1 with the strip thickness d is formed and this product (= the actual mass flow) is regulated to the desired mass flow M *.

The control device 6 can be implemented in individual cases circuit technology. In general, the control device 6, however, according to the illustration of FIG. 1 designed as a software programmable controller 6. This is in FIG. 1 indicated by the letters "μP" (for microprocessor). In this case, the control device 6 executes a computer program 10 with which the control device 6 is programmed.

The computer program 10 has according to FIG. 1 Machine code 11, which is directly executable by the control device 6. In this case, executing the machine code 11 by the controller 6 causes the controller 6 to control the cold rolling line according to the above-explained control method.

The computer program 10 can be supplied to the control device 6 in any manner. For example, a supply via a computer-computer connection is possible. Examples of suitable computer-computer connections are a local area network (LAN) and the World Wide Web. Alternatively, it is possible to supply the computer program 10 to the control device 6 via a data carrier 12, on which the computer program 10 is stored in machine-readable form. Examples of suitable data carriers 12 are a CD-ROM, a USB memory stick or an SD memory card. For example, in FIG. 4 the data carrier 12 is designed as a USB memory stick.

The present invention has many advantages. In particular, a defined mass flow and at the same time a correct strip thickness can be achieved in a simple manner. Therefore, it is only necessary for the roll stands 2, which are arranged downstream of the roll stand 2-1 regulated according to the invention, to correctly set the roll peripheral speed vU 'of the respective roll stand 2. This can alternatively take place in that behind the respective rolling stand 2 (for example, the second rolling stand 2-2) by means of a corresponding speed detection device 13, the actual Actual speed is detected and controlled behind this rolling stand 2 or that over a corresponding roll gap model, the respective overfeed is modeled and in this rolling stand 2-2 outlet side desired belt speed is converted into the corresponding circumferential roll speed vU '. Behind the last roll stand 2-n, a conventional monitor control for the last fine correction of the final strip thickness (that is, for the strip thickness of the cold strip 1 behind the last rolling stand 2-n) may be provided.

The regulation of the mass flow according to the invention shows its advantages not only under static operating conditions, but above all under dynamically changing operating conditions such as, for example, the threading operation, the passage of a weld seam or the changing of the setpoint speed v *. It also results in these operating conditions improved dimensional accuracy of the final strip thickness. Furthermore, the extent of the required adaptation of the roll gap model 7 is a direct indication of the quality of the roll gap model 7. This indicator can also be used generally for optimizing process models for the cold rolling mill. The dynamic of the control is limited - even in dynamic operating conditions - only by the speed of the cruise control. Furthermore, a continuation of the operation of the cold rolling mill is possible even in case of failure of the speed detection.

The above description is only for explanation of the present invention. The scope of the present invention, however, is intended to be determined solely by the appended claims.

Claims (13)

1. Regulation method for a cold rolling train having a number of roll stands (2), through which a cold rolled strip (1) successively runs,

   - wherein an actual velocity (v) with which the cold rolled strip (1) is discharged from one (2-1) of the roll stands (2) is detected by measurement technology,

   - wherein a strip thickness (d) with which the cold rolled strip (1) is discharged from the roll stand (2-1) concerned is also detected,

   characterised i n that the detected actual velocity (v) is compared with a corresponding setpoint velocity (v*) and, on the basis of the comparison, a setpoint value (vU*) for a circumferential roll velocity (vU) of the roll stand concerned (2-1) is adjusted, so that the actual velocity (v) is adapted to the setpoint velocity (v*),

   - wherein the detected roll stand (2-1) is activated in accordance with the adjusted setpoint value (vU*) for the circumferential roll velocity (vU) of the roll stand concerned (2-1),

   - wherein a nip (s) of the roll stand concerned (2-1) is adjusted on the basis of at least the detected strip thickness (d) such that the product of actual velocity (v) of the cold rolled strip (1) and strip thickness (d) corresponds to a desired mass flow (M*).
2. Regulation method according to claim 1,
   characterised in that the setpoint value (vU*) for the circumferential roll velocity (vU) of the roll stand concerned (2-1) is determined on the basis of the setpoint velocity (v*) and an advance (a) determined on the basis of a model and that the adjustment of the setpoint value (vU*) for the circumferential roll velocity (vU) of the roll stand concerned (2-1) is realised by the model (7), by means of which the advance (a) is determined, being adapted on the basis of comparing the actual velocity (v) with the setpoint velocity (v*).
3. Regulation method according to claim 1 or 2,
   characterised in that the nip (s) of the roll stand concerned (2-1) is adjusted exclusively on the basis of the detected strip thickness (d).
4. Regulation method according to claim 1 or 2,
   characterised in that the nip (s) of the roll stand concerned (2-1) is adjusted on the basis of the product of actual velocity (v) of the cold rolled strip (1) and strip thickness (d).
5. Regulation method according to one of the preceding claims,
   characterised in that the roll stand (2-1) concerned is the first roll stand (2-1) of the cold rolling train through which the cold rolled strip (1) passes.
6. Control device of a cold rolling train having a number of roll stands (2) through which a cold rolled strip (1) successively passes,

   - wherein the control device is supplied with an actual velocity (v), detected by measurement technology, with which the cold rolled strip (1) is discharged from one (2-1) of the roll stands (2),

   - wherein the control device is also supplied with a strip thickness (d) detected by measurement technology, with which the cold rolled strip (1) is discharged from the roll stand (2-1) concerned,

   characterised in that the control device compares the actual velocity (v) supplied to it with a corresponding setpoint velocity (v*) and on the basis of the comparison, adjusts a setpoint value (vU*) for a circumferential roll velocity (vU) of the roll stand concerned (2-1), so that the actual velocity (v) is adjusted to the setpoint velocity (v*),

   - wherein the control device activates the roll stand (2-1) concerned in accordance with the adjusted setpoint value (vU*) for the circumferential roll velocity (vU) of the roll stand concerned (2-1),

   - wherein the control device adjusts a nip (s) of the roll stand concerned (2-1) on the basis of at least the strip thickness (d) supplied to it, such that the product of actual velocity (v) of the cold rolled strip (1) and strip thickness (d) corresponds to a desired mass flow rate (M*).
7. Control device 5 according to claim 6,
   characterised in that the control device determines the setpoint value (vU*) for the circumferential roll velocity (vU) of the roll stand concerned (2-1) on the basis of the setpoint velocity (v*) and an advance (a) determined on the basis of a model and that the control device realises the adjustment of the setpoint value (vU*) for the circumferential roll velocity (vU) of the roll stand concerned (2-1) in that it adapts the model (7), by means of which the advance (a) is determined, on the basis of the comparison of the actual velocity (v) with the setpoint velocity (v*).
8. Control device according to claim 6 or 7,
   characterised in that the control device adjusts the nip (s) of the roll stand concerned (2-1) exclusively on the basis of the detected strip thickness (d).
9. Control device according to claim 6 or 7,
   characterised in that the control device adjusts the nip (s) of the roll stand concerned (2-1) on the basis of the product of the actual velocity (v) of the cold rolled strip (1) and strip thickness (d).
10. Control device according to one of claims 6 to 9,
    characterised in that it is embodied as a software-programmable control device.
11. Computer program comprising machine code (11) which is able to be executed directly by a control device (6) of a multi-stand cold rolling train and the execution of which by the control device (6) causes the control device (6) to regulate the cold rolling train in accordance with a regulation method according to one of claims 1 to 5.
12. Computer program according to claim 11,
    characterised in that it is stored on a data medium (12) in machine-readable form.
13. Cold rolling train,

    - wherein the cold rolling train comprises a number of roll stands (2) through which a cold rolled strip (1) successively passes,

    - wherein the cold rolling train has a velocity detection device (4) which is disposed downstream from one (2-1) of the roll stands (2) and by means of which an actual velocity (v) with which the cold rolled strip (1) is discharged from the roll stand (2-1) concerned is measured,

    - wherein the cold rolling train has a thickness detection device (5) which is arranged downstream from the roll stand (2-1) concerned and by means of which a strip thickness (d) with which the cold rolled strip (1) is discharged from the roll stand (2-1) concerned is detected,

    - wherein the cold rolling train has a control device (6) according to one of claims 6 to 10, so that the cold rolling train is operated in accordance with a regulation method according to one of claims 1 to 5.

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