FLATNESS MEASUREMENT IN ROLLING MILLS FOR HOT ALUMINUM METAL STRIP

Description

field of technology

[0001] The present invention is based on a rolling device for a hot metal strip made of aluminum, wherein the rolling device comprises a rolling stand, wherein the rolling device comprises a coiler device arranged on the outlet side of the rolling stand with a coiler and a rear deflection roller, wherein the rear deflection roller is arranged between the rolling stand and the coiler, wherein the rolling device comprises a measuring arrangement arranged between the rolling stand and the rear deflection roller, configured to determine a flatness of the metal strip, wherein the measuring arrangement comprises a mechanical excitation device by means of which the metal strip can be excited to a mechanical oscillation in its thickness direction, wherein the measuring arrangement comprises a measuring device by means of which the amplitude of the excited mechanical oscillation of the respective region of the metal strip can be detected for a plurality of regions of the metal strip lying next to one another in the width direction of the metal strip. State of the art

[0002] Such a rolling device is known for rolling mills for cold rolling steel. Purely as an example, reference can be made to WO 98 / 38482 A1. The flatness of the metal strip can be determined from the recorded amplitudes of the mechanical vibrations of the metal strip regions. This is also explained in more detail in the aforementioned WO document. Summary of the invention

[0003] When rolling metal strip, the flatness of the rolled metal strip is an important quality feature. In particular, it is important to prevent the rolled metal strip from becoming wavy after rolling. This problem arises equally in the cold rolling of steel and the hot rolling of aluminum. However, while the aforementioned rolling device design is well-known for cold rolling steel, such a rolling device cannot simply be used for hot rolling aluminum. There are several reasons for this.

[0004] One reason is that aluminum strip has different physical properties and thus exhibits different vibration behavior—for example, different natural frequencies—than a steel strip, even with the same rolling equipment geometry. In particular, the natural frequencies of aluminum strip are considerably lower than those of steel strip. To avoid interference caused by the natural vibrations of the aluminum strip, the frequency of the excited mechanical vibration would have to be significantly lower for aluminum strip than for steel strip. This theoretical possibility of operating at a lower frequency proves impractical for practical reasons.

[0005] Another reason is that after hot rolling an aluminum strip, the side edges of the strip must be trimmed. For this purpose, a trimming device is arranged on the outlet side of the rolling stand in a rolling mill for hot rolling an aluminum strip. This device cuts off a strip of metal strip on each side of the aluminum strip. However, the cutting process associated with trimming excites mechanical vibrations at least in the edge regions of the aluminum strip. These vibrations interfere with the correct recording of the amplitudes of the excited mechanical vibrations, at least in the edge regions of the aluminum strip, and therefore falsify the result.

[0006] To measure the flatness of an aluminum strip, contact-based measurement is performed using a segmented tensile measuring roller. This solution has several disadvantages. For example, there is a risk of scratching or otherwise damaging the surface of the aluminum strip. Furthermore, the measurement is relatively inaccurate. The use of a segmented tensile measuring roller is also costly. Finally, there is a risk of damaging the sensors of the segmented tensile measuring roller.

[0007] The object of the present invention is to provide possibilities by means of which a rolling device of the type mentioned at the outset can be modified in such a way that it can be used in a rolling device for a hot aluminum strip.

[0008] The object is achieved by a rolling device having the features of claim 1. Advantageous embodiments of the rolling device are the subject of dependent claims 2 to 12.

[0009] According to the invention, a rolling device of the type mentioned at the outset is designed in that that the rolling device has a trimming device arranged on the outlet side of the rolling stand, by means of which a strip of the metal strip can be severed on each side of the metal strip, so that only a remaining central region of the metal strip is fed to the rear deflection roller and from there to the reel, and that the rolling device has a front deflection roller arranged between the trimming device and the measuring arrangement, by means of which the metal strip can be deflected from a direct connecting line between the rolling stand and the rear deflection roller.

[0010] Due to the trimming device, the rolling device must be a rolling device for rolling aluminum strip. For other metals - especially steel - such trimming devices are neither necessary nor present. By means of the front deflection roller, the metal strip is deflected from an outlet direction in which the metal strip runs out of the rolling stand, into the transport direction in which the metal strip passes the measuring arrangement. The deflection as such - i.e. the change in direction as such - is of secondary importance. In particular, the extent to which the metal strip 1 is deflected by the front deflection roller 8 can be relatively small. A deflection of a few degrees is sufficient, for example a deflection of 5° to 10°. A larger deflection is also easily possible. However, deflection at the front deflection roller achieves two crucial effects.Firstly, the free path over which the aluminum strip can oscillate is shortened. Because of the front deflection roller, the free path no longer extends from the rolling stand or the trimming device to the rear deflection roller, but only from the front deflection roller to the rear deflection roller. This increases the natural frequencies of the aluminum strip in the area of ​​the measuring system. Furthermore, the front deflection roller dampens the vibrations induced in the aluminum strip by the trimming device. The disturbances caused by the trimming device are thus eliminated or at least largely dampened.

[0011] The mechanical excitation device can be designed, in particular, as a suction device, by means of which the metal strip can be periodically subjected to a negative pressure on one side. This design is established, robust, and reliable. The average amplitude of the mechanical vibrations excited by the negative pressure can be adjusted by varying the degree to which air extraction is performed. The frequency of the excited mechanical vibrations can be adjusted by varying the frequency to which the air extraction is performed.

[0012] The measuring device can be designed, in particular, as a contactless measuring device, by means of which the amplitude of the excited mechanical vibration of the respective area of ​​the metal strip can be measured contactlessly. Similar to the design of the mechanical excitation device, this design is also established, robust, and reliable.

[0013] A contactless measuring device can, for example, have a number of electromagnetic excitation devices for inducing eddy currents in the metal strip and at least one electromagnetic receiving device for detecting the amplitude of the mechanical oscillation of the respective region of the metal strip, by means of which the strength of the eddy current excited in the respective region of the metal strip can be detected.

[0014] In particular, a measuring arrangement in which the mechanical excitation device and the measuring device are arranged is used in various rolling mills appropriately equipped by Siemens VAI Metals Technologies GmbH, Linz, Austria. The product name of Siemens VAI Metals Technologies GmbH for the measuring arrangement at the time was SIFLAT. Such a measuring arrangement is also explained in the WO document mentioned above.

[0015] Preferably, the front deflection roller is movable essentially orthogonally to the connecting line between the rolling stand and the rear deflection roller in the thickness direction of the metal strip. The extent of the movement is preferably such that the front deflection roller, in a retracted position, does not deflect the metal strip from the connecting line between the roll gap and the rear deflection roller, but does so in an extended position. This configuration makes it possible, in particular, to initially achieve clean coiling "without interference from the front deflection roller and the measuring arrangement," and only after coiling, i.e., only after a stable state has been reached, is the front deflection roller positioned against the metal strip and deflects it.

[0016] Preferably, the front deflection roller can be adjusted to the metal strip from above. In particular, in this case, the front deflection roller does not have to be arranged in the confined space between the rolling stand and the rear deflection roller. Furthermore, this design is easier to retrofit to an existing rolling mill not yet configured according to the invention.

[0017] It is possible for the front deflection pulley to be mechanically connected to the measuring arrangement so that the front deflection pulley and the measuring arrangement can only be moved together. This design is particularly useful when the front deflection pulley and the measuring arrangement are located on the same side of the metal strip. This can simplify the mechanical design and require fewer actuators. This is especially true if the front deflection pulley is connected to the measuring arrangement via a pivoting lever arm so that when the front deflection pulley is positioned against the metal strip, the distance between the measuring arrangement and the metal strip (or from a line connecting the front and rear deflection pulleys) remains constant when the lever arm is pivoted.

[0018] It is also possible to arrange a central deflection roller between the measuring arrangement and the rear deflection roller. This design allows the free path in the area of ​​the measuring arrangement, which determines the natural frequencies of the metal strip, to be further shortened.

[0019] Preferably, the middle deflection roller is mechanically connected to the measuring assembly, so that the measuring assembly and the middle deflection roller can only be moved together. This automatically ensures that the mechanical excitation device and the measuring device are positioned at the desired distances from the metal strip when the unit comprising the measuring assembly, front deflection roller, and middle deflection roller moves toward the metal strip.

[0020] The measuring device is preferably water-cooled. This makes it possible, in particular, to cool the measuring device sufficiently and thus to perform a flatness measurement using the measuring device even on a very hot aluminum strip.

[0021] Preferably, the distance of the measuring device from the metal strip is adjustable between a minimum and a maximum distance. This allows the distance of the measuring device from the metal strip to be increased, especially if necessary. Such a need may arise, for example, if a water cooling system fails.

[0022] Preferably, the water cooling, the minimum distance and the maximum distance are coordinated with one another in such a way that the measuring device can be operated continuously with water cooling at the minimum distance and can be operated continuously without water cooling at the maximum distance or at least is not damaged despite the thermal effect of the hot metal strip on the measuring device. Short description of the drawings

[0023] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of the embodiments, which are explained in more detail in conjunction with the drawings. Herein, in schematic representation: FIG 1a side view of a rolling device, FIG 2the rolling device of FIG 1 from above, FIG 3 a measuring arrangement and two pulleys from the side, FIG 4 the measuring arrangement from FIG 3 from above, FIG 5 a side view of a rolling device, FIG 6 a side view of a rolling device and FIG 7 a further measuring arrangement and two deflection rollers. Description of the embodiments

[0024] According to the FIG 1 und 2 a rolling device for a metal strip 1 has a rolling stand 2. The rolling stand 2 is in FIG 1 It is depicted as a six-high stand, i.e., a rolling stand that, in addition to its work rolls 3, has intermediate rolls 4 and backup rolls 5. However, the rolling stand 2 could also be designed differently, for example, as a four-high stand, in which, in addition to the work rolls 3, only the backup rolls 5 are present. In this case, the backup rolls 5 would, of course, rest directly on the work rolls 3. Other designs are also possible, for example, as a 20-high rolling stand or a 12-high rolling stand.

[0025] The metal strip 1 is a hot aluminum strip. It has a width b of usually 100 cm or more (sometimes up to 225 cm and even more) and a temperature in the range of over 300 °C, usually between 315 °C and 350 °C. The metal strip 1 is fed to the rolling stand 2 in a conveying direction x. It generally also exits the rolling stand 2 in the same conveying direction x. The conveying direction x is generally horizontal or at least nearly horizontal. The conveying speed at which the metal strip 1 exits the rolling stand 2 can be up to 400 m / min, sometimes even slightly higher.

[0026] On the exit side of the rolling stand 2, a thickness gauge 6, a trimming device 7, a front deflection roller 8, a measuring arrangement 9, and a coiler 10 are arranged, in this order. The coiler 10 has a coiler 11 and a rear deflection roller 12, with the rear deflection roller 12 being arranged between the rolling stand 2 and the coiler 11, more precisely between the measuring arrangement 9 and the coiler 11.

[0027] Another roll stand can be arranged upstream of the roll stand 2 on the inlet side. Several additional roll stands can also be arranged upstream of the roll stand 2 on the inlet side. It is also possible for a coiling device for uncoiling the metal strip 1, for example, to be arranged directly upstream of the roll stand 2. Which of these configurations is present is of secondary importance within the scope of the present invention. For this reason, the configuration of the rolling device on the inlet side of the roll stand 2 is not shown in the figures and will not be explained in detail.

[0028] After leaving the rolling stand 2, the thickness of the metal strip 1 is first measured by means of the thickness measuring device 6 (possibly spatially resolved across the strip width). Thickness measurement is of secondary importance within the scope of the present invention. For this reason, the thickness measuring device 6 is FIG 2 not shown. For the same reason, the analysis of the recorded thickness is not explained in detail.

[0029] Then, by means of the trimming device 7, a strip of the metal strip 1 is cut off on each side of the metal strip 1. Only a remaining central portion of the metal strip 1 is fed to the following elements, i.e., the front deflection roller 8, the measuring arrangement 9, the rear deflection roller 12 and the reel 11. The cut strips are in FIG 2 They are depicted wider relative to the center area than they actually are. In reality, they are usually relatively narrow, typically between 1.5 cm and 4.0 cm.

[0030] By means of the two deflection rollers 8, 12, the direction in which the metal strip 1 is transported is changed.

[0031] In particular, the metal strip 1 is deflected by means of the front deflection roller 8 from a direct connecting line 13 between the rolling stand 2 (more precisely: the roll gap of the rolling stand 2) and the rear deflection roller 12.

[0032] According to the FIG 1 und 2 The front deflection roller 8 can be positioned against the metal strip 1 from above. This configuration is particularly advantageous when the front deflection roller 8 is to be retrofitted to an existing rolling mill—i.e., a rolling mill that does not yet have the front deflection roller 8.

[0033] Regardless of whether the front deflection roller 8 can be adjusted to the metal strip 1 from above or from below, the front deflection roller 8 is movable orthogonally or at least substantially orthogonally to the said connecting line 13 and thus in the thickness direction of the metal strip 1. This is in FIG 1 indicated by a double arrow above the upper deflection roller 8. Furthermore, the positioning of the front deflection roller 8 against the metal strip 1 can be controlled (i.e., uncontrolled) or regulated as required. The drive for positioning the front deflection roller 8 can be electrical, hydraulic, or pneumatic, for example.

[0034] The following are in connection with the FIG 3 und 4 the structure and mode of operation of the measuring arrangement 9 is explained in more detail.

[0035] According to FIG 3 The measuring arrangement 9 comprises a mechanical excitation device 14. By means of the mechanical excitation device 14, the metal strip 1 can be excited to a mechanical vibration in its thickness direction. Specifically, the metal strip 1 is in FIG 3 in a solid line in a middle position, in dashed lines in the fully deflected positions. The mechanical excitation device 14 can, for example, be designed as shown in FIG 3 be designed as a suction device. For example, a suction fan 15 can be connected via suction openings 16 (see also FIG 4 ) and a suction channel 17 suck air from the area between the metal strip 1 and the measuring arrangement 9 and thus periodically subject the metal strip 1 to a negative pressure on one side. The extent to which air is sucked out can be varied by directly controlling the suction fan 15 and / or by controlling a modulator element 18. When the modulator element 18 is controlled, the modulator element 18 periodically varies the cross-section and thus the flow resistance of the suction channel 17. The modulator element 18 can, for example, be designed as an oval or elliptical element that is rotated in the suction channel 17.

[0036] The frequency at which the metal strip 1 mechanically oscillates is determined by the frequency at which the excitation device 14 excites the metal strip 1 to mechanical oscillation. Typically, the frequency is in the upper single-digit or low double-digit Hertz range, i.e., between 5 Hz and 30 Hz. It is usually between 8 Hz and 20 Hz, in particular between 10 Hz and 15 Hz. The amplitude of the mechanical oscillation of the metal strip 1 can be adjusted by the extent of air extraction. The air extraction is usually adjusted such that the amplitude of the mechanical oscillation of the metal strip 1 is in the range between 50 µm and 200 µm, in particular between 80 µm and 125 µm.

[0037] The measuring arrangement 9 further comprises a measuring device 19, by means of which for several areas 20 of the metal strip 1 (see the FIG 2 and 4) the respective amplitude Ai (with i = 1, 2, ... n and n = number of areas 20) of the excited mechanical vibration of the respective area 20 of the metal strip 1 can be recorded. The areas 20 are located in the FIG 2 and 4 side by side as seen in the width direction of the metal strip 1. The total number of eight areas 20 shown is purely exemplary.

[0038] From the determined amplitudes Ai, the flatness of the metal strip 1 can be determined in a known manner. In the following, KWi denotes the inverse of the respective amplitude Ai of the respective area 20. Therefore, the relationship applies to all areas 20 KWi = 1 Ai

[0039] Furthermore, KW (without the index i) denotes the mean of the reciprocal values ​​KWi: KW = 1 n ∑ i KWi

[0040] Thus, based on the relationship δσi = σi KWi − KW KW For the i-th region 20, the deviation δσi of the specific stress σi is determined. The specific stress σi for the i-th region 20 is the mean value of the specific stresses σi determined for the individual regions 20, weighted if necessary by the thicknesses of the respective regions 20. From the deviations δσi of the specific stress σi, the flatness can then be determined in a conventional manner.

[0041] The evaluation of the determined amplitudes Ai or the determination of the flatness of the metal strip 1 is not the subject of the present invention as such. Rather, the subject of the present invention is the design of the rolling device, which enables the acquisition of the measured values ​​from which the amplitudes Ai can be determined.

[0042] The measuring device 19 can be designed, in particular, as a contactless measuring device, i.e., as a measuring device 19 by means of which the amplitudes Ai of the excited mechanical vibration of the regions 20 of the metal strip 1 can be detected without contact. For example, the measuring device 19 can have a number of electromagnetic excitation devices 21 by means of which eddy currents are induced in the metal strip 1. In individual cases, it is possible that only a single electromagnetic excitation device 20 is present. Sometimes, several electromagnetic excitation devices 21 can be present, each of which induces eddy currents in several regions 20. According to FIG 4 The measuring device 19 can have such an electromagnetic excitation device 21 for each area 20 of the metal strip 1. The respective excitation device 21 can be designed as an excitation coil. The excitation devices 21 are subjected to a - uniform or individually adjusted - excitation current IA. The application of the excitation current IA is in FIG 4 shown only for one of the excitation devices 21.

[0043] The excitation current IA has an excitation frequency. The excitation frequency is usually in the range of several kHz, sometimes even in the single-digit MHz range. The excitation currents IA induce eddy currents in the metal strip 1. The eddy currents, in turn, can be sensed and detected by electromagnetic receiving devices 22. The electromagnetic receiving devices 22 are individually assigned to the regions 20. Thus, at least one electromagnetic receiving device 22 is present for each region 20. The electromagnetic receiving devices 22 can be designed as receiving coils. The electromagnetic receiving devices 22 supply sensed sensor currents ISi (where the index i again stands for the respective region 20). The magnitude of the respective sensor current ISi is characteristic of the strength of the eddy current excited in the respective region of the metal strip 1.From the ratio of the respective sensor current ISi to the - if applicable - excitation current IA, the respective current distance of the respective area 20 of the metal strip 1 from the measuring device 19 can be determined in a conventional manner. The temporal development of this distance provides the amplitude Ai of the mechanical oscillation of the respective area 20 of the metal strip 1. From the amplitudes Ai, as already explained, the flatness of the metal strip 1 can then be determined.

[0044] To determine the distances between the regions 20, it may be necessary to determine a sensitivity generally for all regions 20 or specifically for the respective region 20. This sensitivity can be determined by means of a factor that allows the distance to be determined from the ratio of the respective sensor current ISi to the excitation current IA. The determination of such a sensitivity can be carried out in experiments.

[0045] It is possible that the measuring arrangement 9 - in particular the measuring device 19 - can withstand the harsh operating conditions, especially the high temperature load caused by the hot metal strip 1, without active cooling. However, the measuring device 19 is usually water-cooled. This is due to FIG 4 This can be seen in the fact that (relatively cold) cooling water 23 is supplied to the measuring device 19 and the cooling water 23 (after cooling the measuring device 19) is discharged again from the measuring device 19.

[0046] As a rule, a distance a between the measuring device 19 and the metal strip 1 is adjustable. The distance a relates to the non-deflected state of the metal strip 1. For example, the measuring device 19 can be arranged so as to be movable within the measuring arrangement 9, or the measuring arrangement 9 can be moved as a whole. The distance a is adjustable between a minimum distance (e.g., fully extended) and a maximum distance (e.g., fully retracted). At the minimum distance, the measuring device 19 can be operated continuously, provided the water cooling system is working. The operation of the water cooling system can, for example, be monitored. If, however, the water cooling system is not working - for example, because it fails - continued operation of the measuring device 19, or in some cases even leaving the measuring device 19 at the minimum distance at all, would in many cases very quickly lead to damage to the measuring device 19.Therefore, when the water cooling system is not operating, the measuring device 19 is retracted, preferably to the maximum distance. At this maximum distance, the measuring device 19 is at least not damaged despite the thermal effects of the hot metal strip 1. During operation, the distance a of the measuring device 19 from the metal strip 1 (which essentially corresponds to the minimum distance) is usually in the range of a few mm, for example, between 2 mm and 5 mm.

[0047] The maximum distance can be considerably greater than the minimum distance. In some cases, due to the greater distance, the now smaller sensor currents ISi are so small that a meaningful evaluation of the sensor currents ISi and thus the determination of the mechanical vibration amplitudes Ai of the regions 20 of the metal strip 1 is no longer possible. In some cases, however, continued operation of the measuring device 19 (including the resulting determination of the mechanical vibration amplitudes Ai of the regions 20 of the metal strip 1) may still be possible despite the maximum distance.

[0048] In the design according to the FIG 1 und 2 the front deflection roller 8 is arranged above the metal strip 1, while the measuring arrangement 9 is arranged below the metal strip 1. In this case, when the front deflection roller 8 and the measuring arrangement 9 are arranged on different sides of the metal strip 1, the front deflection roller 8 is usually a separate device from the measuring arrangement 9. However, if the front deflection roller 8 and the measuring arrangement 9 are located on the same side of the metal strip 1, it can be arranged as shown in FIG 5 It may be useful to mechanically connect the front deflection roller 8 to the measuring arrangement 9 so that the measuring arrangement 9 and the front deflection roller 8 can only be moved together. For example, the front deflection roller 8 can be connected to the measuring arrangement 9 via a lever arm 24 which is pivotally mounted at a bearing point 25. With a suitable choice of the bearing point 25, it can be achieved that when the lever arm 24 is pivoted, the distance between the measuring arrangement 9 and the metal strip 1 remains constant. The bearing point 25 can, for example, coincide with the axis of rotation of the rear deflection roller 12 or be located in the immediate vicinity of this axis of rotation.

[0049] The condition that the distance of the measuring arrangement 9 from the metal strip 1 remains constant is, of course, only fulfilled if the front deflection roller 8 is positioned against the metal strip 1. If the front deflection roller 8 is spaced from the metal strip 1, the distance of the front deflection roller 8 from the metal strip 1 varies, and thus also the distance of the measuring arrangement 9 from the metal strip 1.

[0050] Furthermore, according to the presentation in FIG 6 It is possible to arrange a central deflection roller 26 between the measuring arrangement 9 and the rear deflection roller 12. This configuration allows the effective length over which the metal strip 1 can be excited to mechanical vibration to be kept particularly short. Furthermore, the direction in which the metal strip 1 is conveyed between the front and central deflection rollers 8, 26 can be adjusted independently of the distance a between the metal strip 1 and the measuring arrangement 9.

[0051] The middle pulley 26 can, as in FIG 7 shown be mechanically connected to the measuring arrangement 9, so that the measuring arrangement 9 and the middle deflection roller 26 can only be moved together. This design is particularly advantageous if, as shown in FIG 7In addition to the middle deflection roller 26, the front deflection roller 8 is also mechanically connected to the measuring arrangement 9, thus forming a structural unit. In this case, when the metal strip 1 is wound up, the structural unit of measuring arrangement 9, front deflection roller 8 and middle deflection roller 26 can be held in a retracted position, so that problem-free winding of the metal strip 1 is possible. After winding up, the structural unit is then extended so that the front deflection roller 8 and the middle deflection roller 26 deflect the metal strip 1. Due to the combination of measuring arrangement 9, front deflection roller 8 and middle deflection roller 26 to form the structural unit, the distance of the measuring arrangement 9 from the metal strip 1 is also necessarily and automatically adjusted.

[0052] The present invention has many advantages. In particular, it enables the simple and reliable acquisition of measured values ​​during the coiling of the hot aluminum metal strip 1, which can be used to determine the flatness of the hot metal strip. List of reference symbols

[0053] 1Metal strip 2Roll stand 3Work rolls 4Intermediate rolls 5Back-up rolls 6Thickness measuring device 7Trimming device 8Front deflection roller 9Measuring arrangement 10Reel device 11Reel 12Rear deflection roller 13Connecting line 14Mechanical excitation device 15Suction fan 16Suction openings 17Suction channel 18Modulator element 19Measuring device 20Areas 21Electromagnetic excitation devices 22Electromagnetic receiving devices 23Cooling water 24Lever arm 25Bearing point 26Middle deflection roller aDistance AiAmplitudes bWide IAAexcitation currents ISiSensor currents xConveying direction

Claims

1. Rolling device for a hot metal strip (1) from aluminum, - wherein the rolling device has a roll stand (2); - wherein the rolling device has a coiling device (10) disposed on the outlet side of the roll stand (2), having a coiler (11) and a rear deflection roller (12); - wherein the rear deflection roller (12) is disposed between the roll stand (2) and the coiler (11); - wherein the rolling device has a measuring assembly (9) which is disposed between the roll stand (2) and the rear deflection roller (12) and is specified to determine a flatness of the metal strip; - wherein the measuring assembly (9) has a mechanical excitation device (14) by means of which the metal strip (1) in the thickness direction thereof is excitable to mechanically oscillate; - wherein the measuring assembly (9) has a measuring device (19) by means of which, for a plurality of regions (20) of the metal strip (1) that lie next to one another in the width direction of the metal strip (1), the amplitude of the excited mechanical oscillation of the respective region (20) of the metal strip (1) is detectable, characterized - in that the rolling device has a trimming device (7) which is disposed on the outlet side of the roll stand (2) and by means of which one band of the metal strip (1) is in each case able to be severed on both sides of the metal strip (1) so that only one remaining central region of the metal strip (1) is supplied to the rear deflection roller (12) and from the latter to the coiler (11); and - in that the rolling device has a front deflection roller (8) which is disposed between the trimming device (7) and the measuring assembly (9) and by means of which the metal strip (1) is able to be deflected from a direct connecting line (13) between the roll stand (2) and the rear deflection roller (12).

2. Rolling device according to Claim 1, characterized in that the mechanical excitation device (14) is configured as a suction device by means of which the metal strip (1) on one side is able to be periodically impinged with a vacuum.

3. Rolling device according to Claim 1 or 2, characterized in that the measuring device (19) is configured as a measuring device operating in a contactless manner, by means of which the amplitude of the excited mechanical oscillation of the respective region (20) of the metal strip (1) is detectable in a contactless manner.

4. Rolling device according to Claim 3, characterized in that the measuring device (19) for inducing eddy currents in the metal strip (1) has a number of electromagnetic excitation devices (21), and for the detection of the amplitude of the mechanical oscillation of the respective region (20) of the metal strip (1) has in each case at least one electromagnetic receiver device (22) by means of which the intensity of the eddy current excited in the respective region (20) of the metal strip (1) is detectable.

5. Rolling device according to one of the preceding claims, characterized in that the front deflection roller (8) in the thickness direction of the metal strip (1) is movable substantially orthogonally to the direct connecting line (13) of the roll stand (2) and the rear deflection roller (12).

6. Rolling device according to one of the preceding claims, characterized in that the front deflection roller (8) is actuatable onto the metal strip (1) from above.

7. Rolling device according to one of the preceding claims, characterized in that the front deflection roller (8) is mechanically connected to the measuring assembly (9) such that the front deflection roller (8) and the measuring assembly (9) are movable only conjointly, and in that the front deflection roller (8) and the measuring assembly (9) are located on the same side of the metal strip (1).

8. Rolling device according to Claim 7, characterized in that the front deflection roller (8) by way of a pivotably mounted lever arm (24) is connected to the measuring assembly (9) so that when the front deflection roller (8) is actuated onto the metal strip (1) a spacing of the measuring assembly (9) from the metal strip (1) remains constant when pivoting the lever arm (24).

9. Rolling device according to one of the preceding claims, characterized in that a central deflection roller (26) is disposed between the measuring assembly (9) and the rear deflection roller (12).

10. Rolling device according to Claim 8, characterized in that the central deflection roller (26) is mechanically connected to the measuring assembly (9) such that the central deflection roller (26) and the measuring assembly (9) are movable only conjointly.

11. Rolling device according to one of the preceding claims, characterized in that the measuring device (19) is water-cooled.

12. Rolling device according to one of the preceding claims, characterized in that a spacing (a) of the measuring device (19) from the metal strip (1) is adjustable between a minimum spacing and a maximum spacing.

13. Rolling device according to Claims 11 and 12, characterized in that the water cooling, the minimum spacing, and the maximum spacing are mutually adapted in such a manner that the measuring device (19) at the minimum spacing is able to be operated permanently with water cooling, and at the maximum spacing is also able to be operated permanently without water cooling or at least is not damaged by the thermal effect of the hot metal strip (1) on the measuring device (19).