Method for operating a rolling installation

Abstract

The invention relates to a method for operating a rolling mill with at least one rolling stand for rolling strip material and a corresponding rolling mill. According to the method according to the invention, the rolled strip is first threaded into the rolling stand F1 with its strip head leading, subsequently reduced in thickness according to a pass plan, and then wound with its strip head leading into a coil 220 using a reeling device 110.To reduce coil roll, the inventive method provides that, prior to performing the stitching operation, a strip point K is defined at a distance from a reference position on the strip material 200 such that, when the strip material is wound onto the mandrel, strip point K lies at an angular position with a predetermined angular distance β to the angular position of the reference position R, where β is: β > -1° or β < -10° if the coil 220 is wound from above, or β > 10° or β ≤ 1° if the coil 220 is wound from below. The strip material is then tracked as it passes through the rolling mill so that the stitching operation can be performed at the first strip point K on the rolled strip.

Description

[0001] The invention relates to a method for operating a rolling mill with at least one rolling stand for rolling strip material, in particular metal strip. Furthermore, the invention also relates to said rolling mill, either in the form of a cold rolling mill or a hot rolling mill.

[0002] In the prior art, the rolling of metal strip typically takes place under tension, meaning the metal strip, which undergoes a thickness reduction during rolling, is typically clamped, for example, between two adjacent rolling stands. The consistency of the strip tension is crucial for the quality of the ultimately rolled strip material. If the strip tension is disturbed during rolling, this degrades the quality of the strip material. A known cause of such a disturbance in the strip tension is the so-called coiling. Coiling typically occurs when the strip head is wound onto a mandrel and subsequently overwound with a few layers of the strip material. This results in an irregular coil with a raised area at a specific angular position in the circumferential direction.The non-round coil, due to its varying diameters distributed around its circumference, causes a difference in the distance between the roll gap of the rolling stand upstream of the coiling reel and the winding point on the non-round coil. This results in cyclical tension disturbances in the strip material. These cyclical tension disturbances, in turn, negatively affect the thickness quality of the strip material.

[0003] In the prior art, e.g., in German patent and publication documents DE 102 34 047 B4 and DE 40 10 352 A1, the frequencies of these tensile disturbances are determined, e.g., from tensile measurements, thickness measurements, measurements of the coil diameter and / or the reel or rotation speeds, in order to then counteract the tensile disturbances in a targeted manner with acceleration additives on the reel and / or with additives on the positioning position of the upstream stand. This is called coil beat compensation.

[0004] While the known methods and systems for fretwork compensation do dampen the effects of fretwork, the process is complex and the effect is not equally effective for all materials and dimensions. Consequently, the system requires extensive optimization before it effectively reduces the fretwork effect as desired.

[0005] The invention is based on the objective of further developing a known method for operating a rolling mill and a corresponding known rolling mill in such a way that the roll edge is reduced even in a wound coil.

[0006] This problem is solved by the method claimed in claim 1. This solution is characterized in that, before a pass is made in a rolling stand, at least one first strip point is defined at such a distance from a reference position on the strip material that, when the strip material is wound onto the mandrel, the first strip point lies at an angular position with a predetermined angular distance β to the angular position of the reference position (R), where β is: β > -1° or β < -10° if the coil (220) is wound from above, or β > 10° or β ≤ 1° if the coil (220) is wound from below, that the strip point on the strip material is tracked during the passage of the strip material through the rolling mill, and that finally a pass is made through the rolling stand at the first strip point.

[0007] The terms "distance" and "angular distance" must be distinguished. While "distance" refers to a strip length, "angular distance" refers to an angle. However, the two terms are physically related, especially since they refer to the same strip material in this description, once unwound and once wound into a coil.

[0008] The angle β is measured relative to an imaginary ray emanating from the center of the coil and passing through the reference point. Positive angles β are measured in the winding direction of the coil, negative angles β against the winding direction. This applies to both top-wound and bottom-wound coils.

[0009] The method according to the invention ensures that, after the strip material has been wound into a coil from above or below, a section of the strip with a thickness reduction is located at an angular position, relative to the reference position on the strip material, that is advantageous for maintaining a coil diameter as constant as possible. The reference position, like the strip section, represents a change in the thickness of the strip material and thus a change in diameter around the circumference of the coil, whereby the thickness change at the reference position represents an increase in diameter, while at the strip section it usually represents a decrease in diameter. In the prior art, these strip sections are typically distributed randomly around the circumference of the coil. Instead, the method according to the invention ensures that the reference position and the strip section where a strip reduction occurs are distributed around the circumference of the coil at the claimed angular distance β.This results in a reduction of the overall out-of-roundness, i.e., the coil runout. This offers the advantage of reducing any disruptions in strip tension caused by out-of-roundness around the coil's circumference. Ultimately, this leads to the benefit of reduced variations in the final thickness profile of the strip material, thus improving the quality of the manufactured strip.

[0010] Because they are each unfavorable with regard to the desired roundness of the wound coil, certain angular distances β between the strip point K and the reference position, namely -1° ≥ β ≥ -10° for coils wound from above and 1° ≤ β ≤ 10° for coils wound from below, were excluded by the claimed definition of β in the method according to the invention.

[0011] The angular distance β = 0° was not excluded because, in this case, with very steep thickness changes, the disruptive overlap and thus the out-of-roundness of the coil are negligible. Such a steep or abrupt thickness change in the strip occurs, for example, when the strip point K is formed at a standstill by closing the rolling stand.

[0012] The method according to the invention is preferably used when rolling strip material under tension; however, this is not a mandatory requirement. Rather, the method according to the invention also reduces coiling even when the strip material is wound onto a reel mandrel without tension.

[0013] The term "stitch" refers to a reduction in thickness or stitch decrease.

[0014] According to a first embodiment of the invention, the strip tension in a rolling mill can be set up in various ways: For example, the strip tension can be set up in the strip material between the rolling stand and the coiling device and / or between the rolling stand and a subsequent further rolling stand or - in the case of rolled stands already erected - between a unit upstream of the rolling mill, e.g. a first coiling device or a pair of drive rolls, and a unit downstream of the rolling mill, e.g. a second coiling device.

[0015] Compared to operating the rolling mill without strip tension, existing strip tension significantly increases the quality, especially the consistency of the thickness profile, of the resulting rolled strip material when making cuts on the strip material.

[0016] According to a further embodiment, in addition to the first strip point, at least one second strip point can be defined on the strip material. This second point is located at such a distance from the reference position that, when the strip material is wound onto the reel mandrel, it lies at a further angular position with a predetermined further angular distance to the reference position. The distance of the reference position from the second strip point is preferably greater than the distance of the reference position from the first strip point. Analogous to the method for the first strip point, it is also necessary for the second strip point to be tracked as the strip material passes through the rolling mill, and for a further pass to be made at the tracked second strip point.The different angular positions claimed for the reference position, the first strip point and the second strip point advantageously result in a further reduction of the coil's out-of-roundness and thus a greater consistency of its final thickness distribution.

[0017] According to another embodiment, the second pass at the second strip point can take place either in the first rolling stand, from which the first pass at the first strip point was already carried out, or in a further rolling stand.

[0018] As mentioned, it is fundamentally important that the reference position, which is, for example, the beginning of the strip, and the first and / or subsequent strip points are each located at different angular positions around the circumference of the coil. It is particularly advantageous if the distances of the first and / or subsequent strip points from the reference position are dimensioned such that the first strip point – viewed in the winding direction – is in front of the reference position, and the second strip point – also viewed in the winding direction – is in front of the first strip point, if the strip is wound onto the reel from above. Alternatively, the distances are dimensioned such that the first strip point – viewed in the winding direction – is behind the reference position, and the second strip point – also viewed in the winding direction – is behind the first strip point, if the strip is wound onto the reel from below.

[0019] The term "winding direction" is used synonymously with the term "rolling direction".

[0020] According to another embodiment, it is also conceivable that at the first and / or the second strip point, not just one pass, but several passes can be made by different rolling stands in order to achieve a greater reduction in thickness.

[0021] Before the strip material is fed into the mill, the roll gap of at least one rolling stand is preset to a desired gap dimension according to a specific production schedule, thus achieving the desired strip thickness. However, the term "preset" can also mean fully extending the rolling stand, in which case no thickness reduction occurs as the strip material passes through the stand. Similarly, "preset" can also mean closing the roll gap, in which case the two work rolls are in contact. Even with such a closed roll gap, the strip material can typically still be fed into the mill because the work rolls are mounted with springs within the rolling stand.

[0022] Finally, the method according to the invention is also applicable to the special case of a reversing rolling mill. In a reversing rolling mill, there is at least one rolling stand, to which a coiler is connected downstream in the rolling direction and another coiler is connected upstream in the rolling direction. The rolling stand is then operated alternately in two opposite rolling directions in a reversing rolling process; that is, the rolling direction is reversed at least once during the rolling process. This further means that the two coilers function either as a winding coiler or an unwinding coiler, depending on the rolling direction. According to the method according to the invention, the special feature of the reversing rolling process is that, in the case of a first rolling direction, the reference position can be formed by the strip head, and after the reversal of direction, in the case of an opposite second rolling direction, the reference position can be formed by the strip foot of the strip material.Alternatively, in reversing rolling operations, the reference position can also be formed by a coiling position detected at the current uncoiler – depending on the current rolling direction.

[0023] The aforementioned problem of the invention is solved by the rolling mill according to claim 10 for non-reversing rolling operation and by the rolling mill according to claim 11 for reversing rolling operation. The advantages of these device-related solutions correspond to the advantages mentioned above with reference to the claimed method.

[0024] The description includes 9 figures, whereby Figure 1 shows a rolling mill according to the invention with a metal strip threaded into a rolling stand; Figure 2 shows the rolling mill according to the invention. Figure 1with the wound strip material on a reeling device; Figure 3 the wound coil with different angular positions for a reference position and a first strip section; Figure 4 the rolling mill according to the invention with two rolling stands and downstream reeling device for creating two strip sections with thickness reduction in the strip material; Figure 5 the resulting coil with the strip material and the two strip sections at different angular positions; Figure 6 the rolling mill according to the invention in the form of the reversing rolling mill during operation in a first rolling direction; Figure 7 the reversing rolling mill according to Figure 6 for operation with a reversed second rolling direction; Figure 8 the resulting coil with an eccentricity determined by measurement at the circumference of the coil as a reference position; and Figure 9 a coil wound from below shows.

[0025] The invention is described in detail below with reference to the figures mentioned, in the form of exemplary embodiments. In all figures, identical technical elements are designated by the same reference numerals.

[0026] Figure 1Figure 1 shows a rolling mill 100 comprising a first rolling stand F1 and a coiling unit 110 downstream of the first rolling stand in the rolling direction W. The coiling unit 110 has a coiling mandrel 112 for winding rolled metal strip 200 into a coil. Before winding, the metal strip 200, with an initial thickness h1e and an initial velocity v1e, arrives at the rolling stand F1 and is threaded onto it. There, it undergoes a pass, i.e., its thickness is reduced to h1x, and it exits the first rolling stand at an exit velocity of v1x, where x represents the exit side of the rolling stand. The initial thickness is greater than the exit thickness, and the initial velocity is less than the exit velocity to maintain mass flow during a pass reduction. The rolling mill 100 is controlled by a control unit 120.A unit 50 can be installed upstream of the rolling mill 100, which provides the strip material 200 for entry into the first rolling stand F1. The unit 50 can be a pre-installed reel mandrel, a pair of drive rollers, or any other device for processing and subsequently discharging the strip material 200. The method according to the invention comprises the following steps:

[0027] First, the strip material 200, with its strip head 201 leading, is threaded into the rolling stand F1 in the rolling direction W. In the rolling stand F1, it undergoes a pass according to a pass plan, with the rolling stand F1 being controlled by the control unit 120. The strip material 200 then exits the rolling stand F1 with a reduced thickness h 1x and a run-out speed v 1x towards the downstream reeling unit 110.

[0028] According to Figure 2The metal strip 200 is then wound from above onto the reel mandrel 112 of the reeling unit 110 with the strip head 201 leading the way. During winding, a strip tension σ2 is created in the metal strip 200 between the first rolling stand F1 and the reel mandrel 112. A strip tension σ3 can also be built up on the inlet side of the first rolling stand F1 between this stand and the unit 50.

[0029] This one just for the Figures 1 and 2 The first pass described, starting at the beginning of the strip 201, is optional: i.e., it can be carried out, but this is not mandatory. Alternatively, the strip can initially enter the rolling stand F1 with its initial thickness h1e and from there, without undergoing any thickness reduction, be conveyed towards the reeling unit 110 and wound up there.

[0030] In the exemplary embodiments according to the Figures 1 and 2After the initial thickness reduction to h 1x, the metal strip undergoes a further thickness reduction at strip point K, starting at the strip head 201. Strip point K is not arbitrarily defined, but rather its distance from a reference position R, here the strip start 201, is defined such that strip point K, when the strip material is wound onto the reel mandrel 112, lies at a defined angular position with a predetermined angular distance β to the angular position of the reference position (R), where β is: β > -1° or β < -10° if the coil (220) is wound from above, or β > 10° or β ≤ 1° if the coil (220) is wound from below. See [reference to relevant section]. Fig. 3Specifically, the inventive method therefore provides that, after defining the distance of strip point K from the reference position, strip point K is tracked on the strip material 200 as it passes through the rolling mill 100, and that a puncture is made in the strip material at point K. The inventive positioning of strip point K at a defined angular position with an angular distance β to the angular position of the reference position, in particular the strip start, offers the advantage that the coil swell, as caused by the reference position or the strip start on the coil, is reduced when the strip start is overwound by further webs of the strip material.

[0031] According to Figure 4The strip material 200 can be thinned not only at strip point K, but also at a second strip point L or at further strip points. To avoid unnecessarily increasing the coil thickness, the inventive method provides that the respective distances of these second and further strip points from the reference position R are defined such that, when the strip material 200 is wound onto the mandrel, these strip points are each located at a different angular position than the first strip point K and the reference position, and outside the angular range associated with the angular distance β, namely -1° ≥ β ≥ -10° for coils wound from above and 1° ≤ β ≤ 10° for coils wound from below. If the second strip point L is to be located further downstream than strip point K, then its distance from the reference position must be chosen to be greater than the distance of strip point K from the reference position R.This applies in particular if the reference position is further upstream, relative to the rolling direction, than both strip positions K and L.

[0032] To realize the second strip point L, the method according to the invention provides that, after determining its distance from the reference position R, the second or further strip point L on the strip material 200 is tracked during its passage through the rolling mill 100, and that a further pass is made at the second strip point L. Preferably, all strip points K, L lie within a circumferential angle range of α = 90° on the coil. Furthermore, preferably, those strip points with the greater distance to the reference position are located in the rolling or winding direction before the strip points with the smaller distance to the reference position. Thus, the strip point L with the greater distance lies before strip point K, and this in turn lies before the reference position R when viewed in the winding direction (=rolling direction); this applies to a coil 200 wound from the top as described above. Figure 5 .

[0033] Several passes can be made at the same strip point, either by the same rolling stand F1 or by different rolling stands F1, F2.

[0034] Figure 6 Figure 1 shows a further embodiment of the rolling mill 100 according to the invention, here in the form of a reversing rolling mill. The rolling mill 100 according to Figure 6 corresponds to the rolling mill according to Figure 1 , however with the opposite rolling direction W1. Accordingly, the left reel unit 110 is unit 50 from Figure 1 , this one in Figure 6 It functions as an unwinding reel. On the right-hand winding reel, the strip point K, viewed in the rolling or winding direction W1, lies in front of the reference position R, which here is again exemplified by the beginning of the strip.

[0035] Figure 7 The reversing rolling mill 100 shows according to Figure 6, however with the opposite rolling and winding direction W2. Here too, in the example case of a strip wound from above over the reel mandrel, the strip point K is again located in the winding direction W2 in front of the reference position R, which reduces the coil roll on the wound coil. In contrast to Figure 6 This marks the end of the tape material 200, which is located at the left unwind reel according to Figure 6 positioned on the inside of the coil there, now according to Figure 7 used as a reference position to calculate the distance of the band point K.

[0036] Figure 8Finally, another embodiment of the reference position R is illustrated. In this reference position, it is not necessarily the beginning or end of the strip, as in the previously shown embodiments, but rather any other prominent point on the strip material, for example, any other protrusion 230 on the circumference of an unwinding coil.

[0037] Fig. 9 This shows a coil wound from below. The angle β is also measured positively in the winding direction. Reference symbol list

[0038] 100 Rolling mill 110 Reel unit 110'Further reel unit 112 Reel mandrel 120 Unit 200 Strip material 201 Strip head 220 Coil 230 Lifting σ1 Strip tension σ2 Strip tension σ3 Strip tension F1 Rolling stand F2 Further rolling stand K Strip position L Strip position R Reference position W Rolling direction = Winding direction W1 First rolling direction = First winding direction W2 Second rolling direction = Second winding direction h nx Thickness of the strip material at the exit of the nth rolling stand h ne Thickness of the strip material at the entrance of the nth rolling stand α Circumferential angle range β, β'Angle intervals v nx speed of the strip material at the exit of the nth rolling stand v ne speed of the strip material at the entry of the nth rolling stand

Claims

1. Method for operating a rolling installation (100) with at least one roll stand (F1) for the rolling of strip material (200), particularly metal strip, with a coiler device (110), which is arranged downstream of the roll stand in rolling direction (W) of the strip material, with a coiler mandrel (112) for winding up of the strip material, after the rolling, on the coiler mandrel (112) to form a coil (220), and with a control device (120) for control of the roll stand (F1) in accordance with a predetermined pass plan, wherein the method comprises the following steps: - introducing the strip material with its strip head (201) foremost into the roll stand (F1); - performing a pass at the strip material (200) in the roll stand (F1) in accordance with the pass plan; and - winding up the strip material (200) with its strip head (201) foremost with the help of the coiler device (110) from above or below to form the coil (220), characterised by - prior to performing the pass: defining at least one first strip point (K) at such a spacing from a reference position (R) at the strip material (200) that the first strip point (K) during winding-up of the strip material (200) on the coiler mandrel (112) lies at an angular position with a predetermined angular spacing β from the angular position of the reference position (R), wherein applicable for β is: β > -1° or β < -10° when the coil (220) is wound from above or β > 10° or β ≤ 1° when the coil (220) is wound from below; - tracking the strip point (K) at the strip material (200) during the running of the strip material (200) through the rolling installation (100); and - performing the pass at the first strip point (K).

2. Method according to claim 1, characterised in that after introduction of the strip material (200) into the roll stand (F1) and prior to performing the pass, the following step is executed: building up a strip tension (σ2) in the strip material (200) between the roll stand (F1) and the coiler device (110) and / or a strip tension (σ1) between the roll stand (F1) and a further rolls stand (F2), which follows in rolling direction, ahead of the coiler device (110) or a strip tension (σ3) between a unit (50), which is upstream of the rolling installation (100), and one of the roll stands or the coiler device (110).

3. Method according to one of the preceding claims, characterised by definition of at least one further, particularly second, strip point (L) at such a spacing from the reference position (R) of the strip material that the second strip point (L) during winding up of the strip material (200) on the coiler mandrel (112) lies at a different angular position from the first strip point (K) and from the reference position (R), wherein the spacing of the reference position (R) from the further, second strip point (L) is greater than the spacing of the reference position (R) from the strip point (K); - tracking the further strip point (L) at the strip material (200) during running of the strip material (200) through the rolling installation (100); and - performing a further pass at the second strip point (L).

4. Method according to claim 2 or 3, characterised in that performance of the second pass at the second strip point (L) takes place in the roll stand (F1) or in the further roll stand (F2).

5. Method according to any one of the preceding claims, characterised in that the spacings of the first and / or second strip point (K, L) from the reference position are so dimensioned that the angular positions for the first strip point (K) and the second strip point (L) lie at the coil ahead of the angular position of the reference position as seen in winding-up direction for the case that the strip is wound from above on the coiler device (110) or the spacings of the first and / or second strip point (K, L) from the reference position are so dimensioned that the angular positions for the first strip point (K) and the second strip point (L) lie at the coil behind the angular position of the reference positions as seen in winding-up direction for the case that the strip is wound from below on the coiler device (110).

6. Method according to any one of the preceding claims, characterised in that in each instance several passes can be carried out by several roll stands at the first and / or second strip point (K, L).

7. Method according to any one of the preceding claims, characterised by the following step: presetting the rolling gap of the at least one roll stand (F1) to a predetermined value prior to the introduction of the strip material, wherein the presetting can also include moving open or closing the rolling gap.

8. Method according to any one of the preceding claims, characterised in that the reference position (R) is the strip head (210).

9. Method according to any one of the preceding claims, characterised in that a further coiler device (110') is upstream of the at least one roll stand (F1) in rolling direction; the at least one roll stand (F1), the coiler device (110, 112) and the further coiler device (110', 112') form a reversing rolling installation and the roll stand (F1) is operated in a reversing rolling operation with a reversal of the rolling direction, characterised in that in the case of a first rolling direction (W1) the reference position (R) is formed by the strip head (201) and after the direction reversal in the case of a second rolling direction (W2) the reference position (R) is formed by the strip foot of the strip material (200); or in the reversing rolling operation the reference position (R) is formed by a coiler runout position (230) detected at the current unwinding coiler according to the current rolling direction.

10. Rolling installation (100) with at least one roll stand (F1) for the rolling of strip material, particularly metal strip, with a coiler device (110), which is arranged downstream of the roll stand (F1) in rolling direction (W1) of the strip material (200), with a coiler mandrel (112) for winding up the strip material (200), after the rolling, on the coiler mandrel (112) to form a coil (220), and with a control device (120) for controlling the roll stand (F1) in accordance with a predetermined pass plan; characterised in that the control device (120) is configured to control the rolling installation (100) for performance of the method according to any one of the preceding claims 1 to 8.

11. Rolling installation (100) in the form of a reversing rolling plant with at least one roll stand (F1) for reversing rolling of strip material, particularly metal strip, with a coiler device (110), which is arranged downstream of the roll stand (F1) in a first rolling direction (1), and with a further coiler device (110'), which is upstream of the roll stand (F1) in the first rolling direction (W1) (200), each with a respective coiler mandrel (112) for winding up the strip material (200), after the rolling, to form a coil (220), and with a control device (120) for controlling the roll stand (F1) in accordance with a predetermined pass plan; characterised in that the control device (120) is configured to control the rolling installation (100) to perform the method according to any one of claims 1 to 7 and claim 9 when dependent on any one of claims 1 to 7.

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