EP2094411B1 - Rolling method for a strip - Google Patents

Abstract

A strip has a strip head and a strip leg. It is rolled, beginning at the strip head, in a roll stand of a rolling device between an upper and a lower roller arrangement of the roll stand. It is monitored whether the strip foot reaches a switching point located, viewed in the rolling direction, in front of the roll stand. From the time the strip leg reaches the switching point, the roller arrangements are subjected to a bending force expanding the roller arrangements by means of an adjusting device, the force being at least as high as a minimal force. The minimal force is at least as high as a balancing force of the upper roller arrangement. The minimal force is determined as a function of the parameters of the strip and/or the operating parameters of the rolling device.

Description

The present invention relates to a rolling process for a belt comprising a belt head and a belt foot, wherein the belt, starting with the belt head, is rolled in a roll stand of a rolling device between an upper and a lower roll arrangement of the roll stand.

The present invention further relates to a computer program comprising machine code, the execution of which by a control device for a rolling stand causes the rolling mill to be operated according to such a rolling method.

Furthermore, the present invention relates to a data carrier on which such a computer program is stored.

The present invention also relates to a control device for a rolling mill, in which such a computer program is stored, wherein the computer program is executable by the control device.

Finally, the present invention relates to a rolling device for rolling a strip, which has at least one rolling stand with an upper and a lower roll arrangement and an adjusting device for applying a bending force to the roll arrangements, wherein the rolling stand is controlled by means of a control device of the type described above.

The objects described above are well known. In particular, any conventional rolling operation is carried out in the manner described above, rolling mill control means are software programmed, and any conventional rolling means is as described above.

In the production of metal strip, in particular of hot strip, the problem may arise in a rolling train that the band foot breaks laterally. So there may be the problem that the actually desired, central course of the tape and thus a trouble for the rolling operation of the rolling device is not ensured.

The lateral breaking of the tape in the horizontal direction can be caused by various physical dependencies. Examples of such dependencies are an unbalanced tension over the bandwidth, a wedge-shaped band cross-section, a skew of the work rolls, an asymmetrical work roll shape, etc.

In order to avoid lateral breakage of the band and the associated disadvantages, it is known in the prior art to lower the tension in the band to zero on the inlet side of the rolling stand. The lowering of the train can be done for example by lowering a loop lifter, which is arranged between the rolling mill and another, upstream arranged roll stand. Alternatively, the nip of the upstream rolling mill can be opened in whole or in part. This procedure has the disadvantage that it has a direct influence on the rolling process as such. In particular, reducing the tension leads to a strong rolling of the strip in the rolling stand. The opening of the upstream rolling mill even has the consequence that the rolling process actually effected in this upstream rolling stand is completely or partially omitted.

Another measure taken in the state of the art is to arrange segmented tension measuring rollers in front of or behind the rolling stand, that is to say looper, by means of which the tension over the belt width can be detected. The detected tensile stresses can serve as the basis of a control in this case, which counteracts the lateral breaking of the tape. However, segmented tension measuring rollers are very expensive. Furthermore, the effectiveness of this measure is empirically unfounded.

From the JP 11 267 728 A a rolling method of the type mentioned is known in which it is monitored whether the band foot reaches a switching point seen in the rolling direction before the rolling stand, and the roller assemblies from the time at which the band foot reaches the switching point (switching time) by means of an adjusting device a bending force spreading the roller assemblies is applied, which is as large as a Balancierkraft the upper roller assembly. The balancing force of the upper roller assembly is the weight that must be compensated to balance the upper roller assembly, thus preventing the upper roller assembly from sinking onto the lower roller assembly.

From the JP 07 144 211 A For example, there is known a rolling method in which the operation of the rolling device is switched at a time when the belt foot passes a measuring arrangement disposed between the rolling stand and an upstream belt retaining member as seen in the rolling direction.

The object of the present invention is to provide a rolling process and the objects corresponding thereto (computer program, data carrier, control device, rolling device), by means of which a lateral breaking of the belt can be optimally counteracted; without negatively affecting the rolling process.

The object is procedurally achieved in that the roller assembly is acted upon from the switching time with a roll force spreading the roll assembly, which is at least as large as a minimum force. The minimum force is at least as large as the Balancierkraft the upper roller assembly. It is according to the invention in dependence determined by parameters of the belt and / or operating parameters of the rolling device.

Correspondingly, the object is achieved programmatically by a computer program comprising machine code, the execution of which by a control device for a rolling stand causes the rolling stand to be operated according to such a rolling method.

The object is further achieved by a data carrier on which such a computer program is stored in machine-readable form.

In terms of equipment, the object is achieved by a control device for a rolling stand in which such a computer program is stored, which can be executed by the control device.

Finally, the object is also achieved by a rolling device of the type mentioned at the beginning, in which the rolling stand is controlled by means of a control device of the type described last.

In most rolling operations, the strip is clamped between the mill stand and a roll-up upstream retention element. The retaining element may in turn also be a rolling stand.

The switching point is seen in the rolling direction in front of the rolling stand. Depending on the embodiment of the present invention, the switching point can be seen in the rolling direction between the rolling stand and the retaining element or lie in front of the retaining element.

It is possible that it is checked whether the roller arrangements are already acted on the switching time by means of the adjusting device with a bending force spreading the roller assemblies, which is at least as large as the minimum force is. If so, this bending force can be maintained. If not, the bending force is raised to the minimum force. This procedure has the advantage that the rolling process can be continued unchanged if the bending force is already large enough. Only if the bending force is not large enough, it is raised to the minimum force.

It is possible that the changeover point is fixed. Preferably, however, the changeover point is determined as a function of parameters of the belt and / or operating parameters of the rolling device.

The adjusting device generally has a drive-side and an operating-side partial adjustment device. As a rule, there is a symmetrical control of the drive-side and the operating-side partial adjustment device. In individual cases, however, it may be advantageous if, during the rolling of the strip, a functional profile of parameters of the strip and / or operating parameters of the rolling device is detected transversely to the rolling direction and, depending on the detected functional profile, a distribution of the bending force on the drive side and the operator-side partial adjustment device is determined. In this case, an unbalanced distribution of the bending force can result on the two partial adjustment devices.

FIG 1

eine Walzeinrichtung von der Seite,

FIG 2

einen Schnitt durch ein Walzgerüst längs einer Linie II-II in FIG 1 und

FIG 3

ein Ablaufdiagramm.

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

a rolling device from the side,

FIG. 2

a section through a rolling stand along a line II-II in FIG. 1 and

FIG. 3

a flowchart.

According to the 1 and 2 a rolling device has at least one rolling stand 1. The rolling stand 1 has an upper roller arrangement 2 and a lower roller assembly 3. Between the roller assemblies 2, 3, a band 4 is rolled.

The rolling stand 1 also has an adjusting device 5. The adjusting device 5 acts on work rolls of the roller assemblies 2, 3. By means of the adjusting device 5, the roller assemblies 2, 3 are acted upon by a bending force F. Depending on the sign of the bending force F, the adjusting device 5 spreads the roller assemblies 2, 3 or compresses them together.

The rolling device furthermore has a control device 6. The control device 6 is used to control the roll stand 1. The control device 6 is supplied to a computer program 7, which is stored in a data carrier 8 of the control device 6. The data carrier 8 of the control device 6 corresponds to a data carrier in the sense of the present invention.

The computer program 7 comprises machine code 9, which can be executed by the control device 6. When the controller 6 executes the computer program 7, it operates the rolling stand 1 according to a rolling method which will be described below in connection with FIG FIG. 3 is explained in more detail.

According to FIG. 3 The control device 6 first determines the value of a first logical variable START in a step S1. The first logical variable START assumes the value "TRUE" if and only if a tape head 10 of the tape 4 has reached the rolling stand 1.

In a step S2, the control device 6 checks the value of the first logical variable START. Depending on the result of the check, the control device 6 returns to step S1 or proceeds to a step S3.

In step S3, the control device 6 controls the rolling stand 1 in such a way that the rolling stand 1 rolls the strip 4. The control of the roll stand 1 by the control device 6 causes, in particular, that a roll gap s is set and the strip 4 is acted upon by a rolling force FW. Furthermore, the control of the roll stand 1 by the control device 6, that the adjusting device 5 is acted upon by the bending force F. The value of the bending force F is determined by the control device 6 in accordance with the technological requirements of the rolling process. The value may be larger or smaller than a minimum force Fmin and also larger or smaller than the balancing force of the upper roller assembly 2. It can also be negative (ie, the roller assemblies 2, 3 are compressed).

In a step S4, the controller 6 determines the minimum force Fmin. The determination of the minimum force Fmin takes place as a function of parameters of the belt 4 and / or operating parameters of the rolling device. Examples of parameters of the belt 4 are its material properties, their dimensions and their temperature. Examples of operating parameters of the rolling device are a rolling speed v, a picking, a train Z (possibly as a function of the bandwidth b), etc. The minimum force Fmin is determined in step S4 such that it is at least as large as the balancing force of the upper roller assembly is.

In a step S5, the control device 6 determines the value of a second logical variable SHIFT. The second logical variable SHIFT assumes the value "TRUE" if and only if a tape foot 11 of the tape 4 has reached or has passed a changeover point 12.

As in particular from FIG. 1 it can be seen, the band 4 is usually clamped between the roll stand 1 and a viewed in the rolling direction x upstream retaining element 13. The retaining element 13 may in particular itself be a rolling stand. The changeover point 12 can - see again FIG. 1 - Seen in the rolling direction x between the roll stand 1 and the retaining element 13. Alternatively, it is possible that the switching point 12 seen in the rolling direction x is located in front of the retaining element 13. Exemplary for each of these two cases in FIG. 1 a possible switching point 12 shown in dashed lines.

In a step S6, the control device 6 checks the value of the second logical variable SHIFT. Depending on the result of the check, the control device 6 returns to step S3 or to step S7.

In step S7, the control device 6 checks whether the bending force F determined in step S3 is greater than the minimum force Fmin. If this is not the case, the control device 6 raises the bending force F to the minimum force Fmin in a step S8. Otherwise, no action needs to be taken. In this case, the bending force F can be maintained.

In a step S9, the control device 6 determines the value of a third logical variable ENDE. The third logical variable ENDE assumes the value "TRUE" if and only if the belt foot 11 reaches the rolling stand 1.

In a step S10, the control device 6 checks the value of the third logical variable ENDE. Depending on the result of the check, the control device 6 proceeds to a step S11 or terminates the further procedure.

The content of the step S11 essentially corresponds to the step S3. In contrast to step S3, however, the bending force F is no longer determined in step S11, but only maintained. From step S11, the controller 6 returns to step S9.

According to the embodiment of FIG. 3 For example, the bending force F is raised to the minimum force Fmin only when the bending force F is smaller than the minimum force Fmin. Otherwise, the bending force F is maintained. Alternatively, it would be possible always set the bending force F to the minimum force Fmin, that is, to omit the step S7 and always execute the step S8. The procedure of FIG. 3 is preferable, however.

Combined with FIG. 3 Below are two variants of the approach of FIG. 3 explained. The two variants are in FIG. 3 shown combined together. They are, however, independent of each other. They are therefore individually feasible.

According to FIG. 3 is inserted between the steps S3 and S4, a step S12. In step S12, the control device 6 determines the changeover point 12. The determination of the changeover point 12 takes place in the context of step S12 as a function of parameters of the belt 4 and / or operating parameters of the rolling device. The parameters of the belt 4 and the operating parameters of the rolling means may be the same as those mentioned above in connection with the determination of the minimum force Fmin. Step S12 implements the first variant of the procedure of FIG FIG. 3 ,

According to FIG. 3 Step S12 precedes Step S4. Alternatively, however, it could also be arranged downstream of step S4.

und $$\mathrm{Fa}\mathrm{-}\mathrm{Fb}\mathrm{=}\mathrm{\delta F}$$

gelten. Im Ergebnis wird im Rahmen des Schrittes S13 somit eine Aufteilung der Biegekraft F auf die antriebsseitige und die bedienseitige Teilstelleinrichtung 14, 15 ermittelt.According to FIG. 3 Furthermore, the step S9 is preceded by a step S13. In step S13, the control device 6 detects a functional profile of parameters of the belt 4 and / or operating parameters of the rolling device transverse to the rolling direction x. As a function of the detected functional profile-in particular as a function of the tensile stress Z and the rolling force FW-the control device 6 determines a differential force δF in the context of step S14. A drive-side partial adjustment device 14 and an operator-side partial adjustment device 15 of the adjusting device 5 are acted upon by a drive-side bending force Fa and an operating-side bending force Fb, the relationships $$\mathrm{fa}\mathrm{+}\mathrm{Fb}\mathrm{=}\mathrm{F}$$

and $$\mathrm{fa}\mathrm{-}\mathrm{Fb}\mathrm{=}\mathrm{·\; \partial F}$$

be valid. As a result, a division of the bending force F on the drive-side and the operating-side partial adjusting device 14, 15 is thus determined as part of the step S13.

In particular, it can be achieved by means of the present invention that an increased band reduction at the strip edges can be avoided and thus a different material flow at the two rolled strip edges can be prevented. Another advantage is that the rolling process as such is unaffected. In particular, the thickness d of the expiring from the rolling stand 1 band 4 remains unaffected. In particular, this results in higher productivity. Furthermore, mechanical surface damage of the work rolls and also the strip surface can be reduced. Also, the wear of the work rolls can be reduced. This also increases the productivity of the rolling device.

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 (11)

1. Rolling method for a strip (4), which comprises a head (10) of the strip and a tail (11) of the strip,

   - wherein the strip (4) is rolled, beginning with the head (10) of the strip, in a rolling stand (1) of a rolling device between an upper and a lower arrangement of rolls (2, 3) of the rolling stand (1),

   - wherein it is monitored whether the tail (11) of the strip reaches a changeover point (12) lying ahead of the rolling stand (1), as seen in the rolling direction (x),

   - wherein, as from the time at which the tail (11) of the strip reaches the changeover point (12), the changeover time, the arrangements of rolls (2, 3) are subjected by means of a setting device (5) to a bending force (F), which spreads the arrangements of rolls (2, 3) apart and is at least as great as a minimal force (Fmin),

   - wherein the minimal force (Fmin) is at least as great as a balancing force of the upper pair of rolls (2),
   characterized
   in that the minimal force (Fmin) is determined in dependence on parameters of the strip (4) and/or operating parameters of the rolling device.
2. Rolling method according to Claim 1, characterized in that the strip (4) is clamped between the rolling stand (1) and a holding-up element (13) situated upstream, as seen in the rolling direction (x).
3. Rolling method according to Claim 2, characterized in that the changeover point (12) lies between the rolling stand (1) and the holding-up element (13), as seen in the rolling direction (x).
4. Rolling method according to Claim 2, characterized in that the changeover point (12) lies ahead of the holding-up element (13), as seen in the rolling direction (x).
5. Rolling method according to one of the above claims, characterized in that it is checked whether, at the changeover time, the arrangements of rolls (2, 3) have already been subjected by means of the setting device (5) to a bending force (F) which spreads the arrangements of rolls (2, 3) apart and is at least as great as the minimal force (Fmin), and in that, if so, this bending force (F) is maintained and, if not, the bending force (F) is raised to the minimal force (Fmin).
6. Rolling method according to one of the above claims, characterized in that the changeover point (12) is determined in dependence on parameters of the strip (4) and/or operating parameters of the rolling device.
7. Rolling method according to one of the above claims, characterized in that the setting device (5) comprises a setting subdevice (14) on the drive side and a setting subdevice (15) on the operator side, in that, during the rolling of the strip (4), a functional profile of parameters of the strip (4) and/or operating parameters of the rolling device is recorded transversely in relation to the rolling direction (x) and in that, in dependence on the recorded functional profile, a division of the bending force (F) between the setting subdevice (14) on the drive side and the setting subdevice (15) on the operator side is determined.
8. Computer program, which comprises machine code (9), the execution of which by a control device (6) for a rolling stand (1) has the effect that the rolling stand (1) is operated according to a rolling method according to one of the above claims.
9. Data carrier on which a computer program (7) according to Claim 8 is stored in a machine-readable form.
10. Control device for a rolling stand (1) in which a computer program (7) according to Claim 8 that can be executed by the control device is stored.
11. Rolling device for rolling a strip (4), which device comprises at least one rolling stand (1) with an upper and a lower arrangement of rolls (2, 3) and a setting device (5) for subjecting the arrangements of rolls (2, 3) to a bending force (F), wherein the rolling stand (1) is controlled by means of a control device (6) according to Claim 10.

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