Device and method for rolling a metal strip

Abstract

A device and a method for rolling a metal strip. A distance of the upper/lower backup roll at at least one point thereof from a predetermined upper/lower reference point is measured by an upper/lower sensor and the measured values of the sensors are sent to a control device. A strain of the roll stand is calculated using a mathematical model, taking into account the rolling force generated. By the control device, an absolute value of the roll gap and thus the resulting thickness of the rolling stock is determined by the control device on the basis of the measured positions of the backup rolls and the calculated strain of the roll stand.

Claims

1. A device for rolling a metal strip, comprising a roll stand formed by a pair of stands, a pair of work rolls and backup rolls, the backup rolls having an upper backup and lower backup roll, wherein the work rolls and the backup rolls are each supported by respective associated chocks on the roll stand, wherein a roll gap is formed between the work rolls, and the work rolls are each supported by at least one backup roll, and a measuring device is configured to determine a value of the roll gap between the work rolls, wherein each of the respective associated chocks are movably guided by at least one of the upper backup roll and the lower backup roll in the roll stand, and is adjusted vertically by a hydraulic cylinder, wherein the measuring device comprises at least one upper sensor configured to measure a distance from at least one point on the upper backup roll to a predetermined upper reference point, and at least one lower sensor configured to measure a distance from at least one point on the lower backup roll to a predetermined lower reference point, the measuring device comprises a force measuring device positioned between at least one of the respective associated chock of the lower backup roll and the roll stand, wherein the force measuring device is configured to measure a rolling force generated with the roll stand, the measuring device is configured to send signals to a control device, wherein the control device is equipped with at least one mathematical model to calculate a strain of the roll stand, taking into account the rolling force generated, and the control device is configured to determine an absolute value of the roll gap and thus a resulting thickness of a rolling stock on a basis of the measured distance from at least one point on the upper backup roll, distance from at least one point on the lower backup roll and the strain of the roll stand calculated by the mathematical model wherein the absolute value for the roll gap is compared with a target value for the roll gap by the control device, and the hydraulic cylinder is controlled for a vertical displacement of either the upper backup roll or the lower backup roll or both, in order to set the roll gap or the resulting thickness of the rolling stock in a form of the metal strip to a desired target value in a controlled manner.

2. The device according to claim 1, wherein the control device is equipped with a mathematical compensation model with which thermals and wear of the work rolls and/or the backup rolls is calculated.

3. The device according to claim 1, wherein the roll stand has an upper crossbar on which the at least one upper sensor is attached.

4. The device according to claim 1, wherein the roll stand has a lower crossbar on which the at least one lower sensor is attached.

5. The device according to claim 1, wherein the at least one lower sensor is attached to a foundation of the roll stand.

6. The device according to claim 1, wherein the at least one upper sensor and/or the at least one lower sensor are connected to a respective associated adjusting device, wherein a position of the at least one upper or the at least one lower sensor relative to the upper backup roll or the lower backup roll is variable by the respective associated adjusting device.

7. The device according to claim 1, wherein the at least one upper sensor and/or the at least one lower sensor are positioned in relation to a width of the roll stand such that a distance to a point in a center of the backup rolls is measured.

8. The device according to claim 1, wherein the at least on upper sensor and/or the at least one lower sensor are eachan optical sensor, a laser triangulation sensor, or a confocal sensor.

9. The device according to claim 8, wherein a blowing device is provided adjacent to the at least one upper sensor and another blowing device is provided adjacent to the at least one lower sensor, and compressed air is introduced into a space between respective backup roll and sensor using the blowing devices.

10. The device according to claim 1, wherein the at least one upper sensor and/or the at least one lower sensor are eddy current sensors.

11. The device according to claim 1, wherein the at least one upper sensor or the at least one lower sensor comprises a plurality of upper sensors or lower sensors is provided respectively adjacent to the upper or lower backup roll along a width of an associated backup roll.

12. A method for rolling, comprising: setting roll gap between a pair of work rolls and backup rolls supported by the respective associated chocks on roll stand, measuring a distance of a upper backup roll at least one point thereof from a predetermined upper reference point by an upper sensor, a distance of a lower backup roll at least one point thereof from a predetermined lower reference point by an lower sensor, and the measured distances of the sensors are sent to a control device, calculating a strain of the roll stand with a mathematical model with which the control device is equipped, taking into account the generated rolling force, and determining a resulting thickness of the rolling stock, by the control device, on a basis of the measured distance of the upper backup roll, the measured distance of the lower backup roll, and a strain of the roll stand calculated by the mathematical model an absolute value of the roll gap, comparing the absolute value for the roll gap with a target value for the roll gap, hydraulically adjusting at least one backup roll to adjust the roll gap or the resulting thickness of the rolling stock in the form of the metal strip to the target value in a controlled manner.

13. The method according to claim 12, programming the control device with respect to the mathematical model in such a way that parts of the strain of the roll stand which have been determined directly by measuring the positions of the backup rolls, are removed from a stand spring.

14. The method according to claim 12, wherein the control device is equipped with a mathematical compensation model with which thermals and wear of the work rolls and/or the backup rolls are calculated, wherein the hydraulic adjustment of the at least one backup roll are taken into account in order to set the roll gap or the resulting thickness of the rolling stock in the form of the metal strip to the target value in a controlled manner.

15. The method according to claim 12, the upper sensor and/the lower sensor are arranged along a width of the respective backup roll.

16. The method according to claim 12, wherein the upper sensor and/or the lower sensor are each designed as optical sensors.

17. The method according to claim 16, wherein a blowing device is provided adjacent to the upper sensor and another blowing device is provided adjacent to the lower sensor, and compressed air is introduced into a space located between respective backup roll and sensor.

18. The method according to claim 12, wherein the upper sensor and/or the lower sensor are eddy current sensors.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Further advantages and details of the invention follow from the exemplary embodiments described below and from the drawings. Showing:

(2) FIG. 1 a simplified view of a device according to the invention for rolling a metal strip,

(3) FIG. 2 a simplified view of a device for rolling a metal strip according to another embodiment of the invention,

(4) FIG. 3 a simplified view of the device according to the invention from FIG. 1 or FIG. 2, supplemented by the symbols of a control loop of an associated control device, and

(5) FIG. 4 a simplified view of the device of FIG. 1 or FIG. 2 respectively, according to a further embodiment of the invention, supplemented by the symbols of a control loop of an associated control device.

DETAILED DESCRIPTION

(6) Referring now to FIGS. 1-4, preferred embodiments of a device 10 and associated method for rolling a metal strip according to the present invention are shown and explained. The same features in the drawings are each provided with the same reference symbols. At this point it is pointed out separately that the drawings are merely simplified and in particular is not shown to scale.

(7) FIG. 1 shows a simplified view of parts of the device 10 according to the invention according to a first embodiment. The device includes a roll stand 12 having a pair of stands 14 between which a pair of work rolls 16 are rotatably mounted. Furthermore, an upper backup roll 18 and a lower backup roll 20 are rotatably mounted between the stands 14 and arranged adjacent to a work roll 16, respectively.

(8) In the exemplary embodiment of FIG. 1, the device 10 comprises a total of four rolls, namely, as explained, two work rolls 16 and two backup rolls 18, 20. The associated roll stand 12 of this device 10 is therefore a so-called four-high stand.

(9) The work rolls 16 and the backup rolls 18, 19 are held on the roll stand 12 or the associated stands 14 by respectively assigned chocks E. In FIG. 1 only one of these chocks E is shown tightened for the purpose of a simplified representation.

(10) The chocks E of at least one backup roll 18, 20 are movably guided in the roll stand in the vertical direction and are associated with a hydraulic cylinder 22. This is illustrated by way of example for the upper backup roll 18 in FIG. 1. By means of an actuation of the hydraulic cylinder 22, it is possible to adjust the upper backup roll 18 in the vertical direction and thereby change a distance between the two work rolls 16.

(11) Between the uprights 14 of the roll stand 12, an upper crossbar Q1 and a lower crossbar Q2 are attached.

(12) The device 10 according to the invention comprises a measuring device, by means of which a distance between the two work rolls 16 and thus a resulting roll gap W (cf. FIG. 3, FIG. 4) between the work rolls can be determined.

(13) In the embodiment of FIG. 1, the above-mentioned measuring device comprises at least one upper sensor 24, which is attached to the upper crossbar Q1, and at least one lower sensor 25, which is attached to the lower crossbar Q2. In the representation of FIG. 1, these sensors 24, 25 are simply symbolized in each case by an arrow.

(14) With the upper sensor 24, a distance of the upper backup roll 18 can be measured at least at one point thereof from a predetermined upper reference point P1. In the same way, the lower sensor 25 can be used to measure a distance from the lower backup roll 20 at at least one point here to a predetermined lower reference point P2.

(15) In the context of the present invention, the aforementioned reference points P1 and P2 form fixed points, with respect to which the movement of the backup rolls 18, 20 is measured by means of the sensors 24, 25. For example, these reference points P1, P2 can be fixed on the upper crossbar Q1 or on the lower crossbar Q2, as is symbolized by corresponding circles in the embodiment of FIG. 1.

(16) According to an alternative embodiment, it can be provided for the lower sensor 25 that it is attached to a foundation F (cf. FIG. 1) of the roll stand 12instead of to the lower crossbar Q2. In this case, the predetermined lower reference point P2 is then expediently also fixed to the foundation F.

(17) In the embodiment of FIG. 1, the sensors 24, 25 are each mounted in a central region of the crossbars Q1, Q2. Correspondingly, a distance of the backup rolls 18, 20 in a central region thereof from the predetermined reference points P1, P2 is measured by means of the sensors 24, 25. This means that the upper sensor 24 and the lower sensor 25 are positioned in relation to a width of the roll stand 12 such that these sensors 24, 25 each measure a distance from a point in the middle of the associated backup rolls 18, 20.

(18) The measuring device also includes a force measuring device 30 which is positioned between a chock of a backup roll and the roll stand 12. In the representation of FIG. 1 it is shown, for example, an arrangement for such a force measuring device 30 which is arranged here adjacent to the respective chocks E of the lower backup roll 20. By means of the force measuring device 30 it is possible to measure the rolling force generated in the roll stand 12.

(19) The device 10 according to the invention also comprises blowing devices 28 (cf. FIG. 1) which are arranged adjacent to the upper and lower sensors 24, 25, respectively. By means of these blowing devices 28, it is possible to introduce compressed air 29 into a space R located between a backup roll 18, 20 and the respective sensor 24, 25. For example, such a blowing device 28 can be designed in the form of a blower or ventilator. In any case, such a blowing device 28 and the compressed air 29 generated with it ensure that interfering particles in the space R between the backup rolls 18, 20 and the sensors 24, 25, which particles can be formed from water mist, dirt particles or the like, are effectively removed. This makes a significant contribution to improving the measurement accuracy of the sensors 24, 25 in relation to a movement of the backup rolls 18, 20.

(20) FIG. 2 shows parts of a second embodiment of the device 10 according to the invention. In contrast to the first embodiment of FIG. 1, a plurality of upper sensors 24 and lower sensors 25 are arranged adjacent to the upper backup roll 18 and the lower backup roll 20 which, in the same way as in FIG. 1, are symbolized here in simplified form only by arrows. For example, three sensors 24, 25 are provided here along a width extension of the respective backup rolls 18, 20. In this regard, it goes without saying that the plurality for the upper sensors 24 or lower sensors 25 can also be different from three, that is to say can also be, for example, more or less than three. Otherwise, the embodiment of FIG. 2 corresponds to that of FIG. 1, so that to avoid repetition, reference may be made to the explanations for FIG. 1.

(21) In the following, further features for the device 10 according to the invention and its mode of operation as well as for a method according to the present invention are shown and explained in FIGS. 3 and 4:

(22) The embodiment of FIG. 3 corresponds to the embodiment of FIG. 1 or FIG. 2, with details of a control device 32 and the associated control loop also being shown, which are also part of the device 10 according to the invention.

(23) It should first be pointed out for FIG. 3 that an upper sensor 24 and a lower sensor 25 are arranged in a central region of the associated backup roll 18, 19. This corresponds to the illustration in FIG. 1. Optionally, a plurality of first sensors 24 and second sensors 25 can be arranged along a width of the associated backup roll 18, 20, wherein these additional sensors are symbolized here by dashed arrows. Such a plurality of sensors 24, 25 then corresponds to the illustration in FIG. 2.

(24) FIG. 3 makes it clear that the upper and lower sensors 24, 25 and also the force measuring device 30 are each connected to the control device 32 in terms of signals. In this way, the control device 32 receives information regarding the movements or deformations of the backup rolls 18, 20 that can occur during rolling operation.

(25) The control device 32 is equipped with a mathematical model 34 with which a strain of the roll stand 12 can be calculated, taking into account the rolling force generated. According to the invention, it is important that the measured values for the rolling force measured on the drive side of the roll stand (F.sub.AS) and for the rolling force measured on the operator side of the roll stand (F.sub.BS) are each sent to this mathematical model 34. In this regard, it is pointed out that the rolling forces generated in FIG. 3 are symbolized by corresponding block arrows positioned in the stands 14.

(26) As already explained elsewhere above, the strain of the roll stand 12 can be calculated by the mathematical model 34 according to the invention. In this regard, FIG. 3 illustrates that flattening occurs during rolling operation both between the metal strip B and the work rolls 16 on the one hand and between the work rolls 16 and the backup rolls 18 adjoining them on the other. These flattenings form part of the strain of the roll stand 12, which is calculated using the mathematical model 34.

(27) FIG. 4 illustrates a third embodiment of the device 10 according to the invention. In contrast to the embodiment of FIG. 3, here the sensors 24, 25 are each equipped with adjusting devices 26 with which the position of a respective sensor 24, 25 can be adapted to a different diameter of an associated backup roll 18, 20. This means that, depending on a roll diameter of the respective backup rolls 18, 20, the sensors 24, 25 can be moved vertically in or out of the roll stand 12. In other words, a position of the upper or lower sensor 24, 25 relative to the upper or lower backup roll 18, 20 can be changed by means of the adjusting devices 26, as explained in adaptation to the respective diameter of the backup rolls 18, 20. Regarding their other features the embodiment of FIG. 4 corresponds to that of FIG. 3, so that, in order to avoid repetition, reference may be made to the explanations for FIG. 3.

(28) The other symbols used in FIG. 3 and FIG. 4 are understood as follows: AGC: Automatic Gauge Control: This means an automatic adjustment of the roll gap by means of a corresponding vertical adjustment of at least one backup roll. HGCAs: Hydraulic Gauge Control on the drive side AS: This means an actuation of the hydraulic cylinder 22, which is assigned to a chock E of the upper backup roll 18 on the drive side AS. SAS: This means the distance by which the chock E of the upper backup roll 18 is vertically displaced on the drive side AS when the hydraulic cylinder 22 arranged there is employed. HGCBs: Hydraulic Gauge Control on the operator side BS: This means an actuation of the hydraulic cylinder 22, which is assigned to a chock E of the upper backup roll 18 on the operator side BS. SBS: This means the distance by which the chock E of the upper backup roll 18 is vertically displaced on the operator side BS when the hydraulic cylinder 22 arranged there is employed.

(29) The invention now works as follows:

(30) To roll a metal strip, this is passed between the work rolls 16 of the roll stand 12. In this case, the work rolls 16 are spaced apart from one another, so that a roll gap is formed between the work rolls 16. In FIGS. 3 and 4, the metal strip is denoted by B and the roll gap that occurs between the work rolls 16 including the metal strip B is symbolized by the arrow W.

(31) During rolling operation, a distance from the upper backup roll 18 at at least one point thereof (see FIG. 1) or at, for example, three points along the width extension of the backup roll 18 (see FIG. 2) to the predetermined upper reference point P1 is measured by the upper sensor(s) 24, wherein the resulting measured values are then sent to the control device 32. In the same way, a distance of the lower backup roll 20 at at least one point thereof (see FIG. 1) or at, for example, three points along the width extension of the backup roll 20 (see FIG. 2) to the predetermined lower reference point P2 is measured by the or the lower sensor(s) 25. Then the measurement signals from the sensors 24, 25 are sent to the control device 32.

(32) Taking into account the rolling forces F.sub.AS, F.sub.BS measured by the force measuring devices 30, a strain of the roll stand is calculated by the mathematical model 34, as explained.

(33) According to the method according to the invention, it is then provided that by means of the control device 32 on the basis of the positions of the backup rolls 18, 20 measured by the upper sensor 24 and the lower sensor 25 and a strain of the roll stand 12 calculated by the mathematical model 34 an absolute value of the roll gap W and thus the resulting thickness of the rolling stock is determined, wherein this absolute value (h.sub.Act) for the roll gap W is compared with a target value (h.sub.REF) for the roll gap W by means of the control device 32 and at least based on this the backup roll 18 is then adjusted hydraulically by the hydraulic cylinder 22 in the vertical direction in order to set the roll gap W or the resulting thickness of the rolling stock in the form of the metal strip B to the target value in a controlled manner.

(34) In order to carry out the above-mentioned method according to the invention, the control device 32 is set up accordingly in terms of programming. For the present invention, this means that by means of the control device 32 based on the measured values of the upper and lower sensors 24, 25 with regard to the measured position of the upper/lower backup roll 18, 20 and a strain of the roll stand 12 calculated by the mathematical model 34, an absolute value of the roll gap W and thus the resulting thickness of the rolling stock can be determined. Subsequently, this absolute value h.sub.Act is compared with the target value h.sub.REF for the roll gap W by means of the control device 32 and on the basis of this the hydraulic cylinder 22 is then controlled for the vertical displacement of the associated upper backup roll 18 in order to thereby adjust the roll gap W or the resulting thickness of the rolling stock in the form of the metal strip B to the desired target value.

(35) To further improve the measurement accuracy, the invention can provide for the control device 32 to be equipped with a mathematical compensation model, which is denoted by 36 in FIGS. 3 and 4 and provided with the designation compensation. Using such a mathematical compensation model 36, thermals and wear of the work rolls 16 and/or the backup rolls 18, 20 can be calculated, wherein on the basis of this corresponding correction variable can be introduced into the controlled system.

(36) The present invention has been explained above with reference to possible embodiments of the device 10, which correspond to a so-called four-high stand. As an alternative to this, the device 10 according to the invention can also be designed in the form of a so-called six-high stand, wherein the roll stand 12 is equipped with a total of four backup rolls. In this case, the explanations given above for the backup rolls 18, 20 refer, mutatis mutandis, to the respective outer backup rolls of a six-high stand, in order to adjust the roll gap W or the resulting thickness of the rolling stock in the form of the metal strip B to a desired target value in a controlled manner as a result and in the same way.

LIST OF REFERENCE NUMBERS

(37) 10 Device 12 Roll stand 14 Stand 16 Work roll(s) 18 Upper backup roll 20 Lower backup roll 22 Hydraulic cylinder 24 Upper sensor 25 Lower sensor 26 Adjusting device (for upper sensor 24/lower sensor 25) 28 Blowing device 29 Compressed air 30 Force measuring device 32 Control device 34 Mathematical model 36 Mathematical compensation model B Metallic strip E Chock(s) F Foundation h.sub.REF Target value (for the roll gap W) Q1 Upper crossbar Q2 Lower crossbar P1 Predetermined upper reference point P2 Predetermined lower reference point R Space (between a backup roll 18, 20 and a sensor 24, 25) W Roll gap