Method and device for controlling a parameter of a rolled stock

Abstract

A method and a device for controlling a parameter, for example the profile or the flatness, of a rolled stock in strip form. A cooling jacket that can be brought up to the roll and is designed to be variable in its effective length b in the circumferential direction of the roll is used as a final controlling element.

Claims

1. A method for controlling a parameter of a strip-shaped rolled stock rolled by means of a roll stand, comprising the following steps: measuring the actual parameter P.sub.actual of the rolled stock after a rolling operation; comparing the actual parameter P.sub.actual to a predetermined target parameter P.sub.target for the rolled stock and determining a deviation between the actual parameter and the target parameter control deviation; determining a control signal for controlling at least one actuator as a function of the parameter control deviation, and providing the control signal to the actuator to perform according to the function; wherein the actuator is a cooling jacket associated with a roller of the roll stand; wherein the cooling jacket is designed with a variable effective length in the circumferential direction of the roller; wherein the cooling jacket is provided with at least a first and a second cooling jacket segment, which is respectively provided with a cross-section having the form of a circular arc for covering a surface segment of the roller; and the effective length of the cooling jacket is suitably adjusted by means of the control signal in the circumferential direction as a function of the parameter control deviation, wherein in order to adjust the effective length of the cooling jacket in the circumferential direction of the roller, the first and the second cooling jacket segments are shifted relative to each other in the circumferential direction, so that they are mutually overlapping each other in accordance with the control signal, at least partially.

2. The method according to claim 1, wherein the determination of the control signal comprises the following steps: determining a target value for the flow of the heat to be discharged from the roller based on at least the previously determined parameter control deviation determining the actual flow of the heat that is actually discharged from the roller, determining the heat flow control deviation as a difference between the target value and the actual value for the flow of the heat to be discharged from the roller; and determining the control signal for adjusting the operating length of the cooling jacket in the circumferential direction in accordance with the heat flow control deviation, which is in turn dependent on the parameter control deviation.

3. The method according to claim 1, wherein the effective length of the cooling jacket in the circumferential direction is increased when the target value of the heat flow is greater than the actual value of the heat flow; the effective length of the cooling jacket in the circumferential direction remains unchanged when the target value of the heat flow is the same as the actual value of the heat flow; the effective length of the cooling jacket in the circumferential direction is reduced when the target value of the heat flow is smaller than the actual value of the heat flow.

4. The method according to claim 2, wherein a determination of the actual flow of the heat comprises a determination of the distribution of the heat flow, and the parameter means the profile or the distribution of the flatness in the width direction of the rolled stock.

5. The method according to claim 1, wherein the carrying out of the method takes place in a rolling pause.

6. A method for controlling a parameter of a strip-shaped rolled stock rolled by means of a roll stand, comprising the following steps: measuring the actual parameter P.sub.actual of the rolled stock after a rolling operation; comparing the actual parameter P.sub.actual to a predetermined target parameter P.sub.target for the rolled stock and determining a deviation between the actual parameter and the target parameter control deviation; determining a control signal for controlling at least one actuator as a function of the parameter control deviation, and providing the control signal to the actuator to perform according to the function; wherein the actuator is a cooling jacket associated with a roller of the roll stand; wherein the cooling jacket is designed with a variable effective length in the circumferential direction of the roller; and the effective length of the cooling jacket is suitably adjusted by means of the control signal in the circumferential direction as a function of the parameter control deviation, wherein the cooling jacket is formed from a flexible material which allows adjusting the effective length of the cooling jacket in the circumferential direction of the roller by bending at least parts of the cooling jacket away from the roller, or towards the roller, or by winding or unwinding the flexible material in accordance with the control signal.

7. A method for controlling a parameter of a strip-shaped rolled stock rolled by means of a roll stand, comprising the following steps: measuring the actual parameter P.sub.actual of the rolled stock after a rolling operation; comparing the actual parameter P.sub.actual to a predetermined target parameter P.sub.target for the rolled stock and determining a deviation between the actual parameter and the target parameter control deviation; determining a control signal for controlling at least one actuator as a function of the parameter control deviation, and providing the control signal to the actuator to perform according to the function; wherein the actuator is a cooling jacket associated with a roller of the roll stand; wherein the cooling jacket is designed with a variable effective length in the circumferential direction of the roller; wherein the cooling jacket is provided with at least one rotatable flap, and the effective length of the cooling jacket is suitably adjusted by means of the control signal in the circumferential direction as a function of the parameter control deviation by opening or closing the flap in accordance with the control signal.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Further embodiments of the method according to the invention and of the device according to the invention are the subject matter of dependent claims.

(2) A total of 13 figures are attached to the invention, which show the following:

(3) FIG. 1 a control diagram of the present invention for controlling a parameter of a rolled stock;

(4) FIG. 2 a first embodiment of the cooling jacket according to the invention provided with an adjusted shorter effective length and with a first variant for the actuator;

(5) FIG. 3 the first embodiment of the cooling jacket according to FIG. 2 provided with an adjusted longer effective length;

(6) FIG. 4 the first embodiment of the cooling jacket according to the invention provided with an adjusted shorter effective length and with a second variant for the actuator;

(7) FIG. 5 the first embodiment according to FIG. 4 provided with an adjusted longer effective length;

(8) FIG. 6 a second embodiment according to the invention for the cooling jacket provided with an adjusted short effective length;

(9) FIG. 7 the second embodiment according to FIG. 6 provided with an adjusted longer effective length;

(10) FIG. 8 a third embodiment of the cooling jacket according to the invention in a first adjustment variant;

(11) FIG. 9 the third embodiment of the cooling jacket in a second adjustment variant;

(12) FIG. 10 the third embodiment of the cooling jacket in a third adjustment variant;

(13) FIG. 11 the third embodiment of the cooling jacket with a fifth adjustment variant;

(14) FIG. 12 a top view of a roller with a plurality of cooling jackets arranged next to each other in the axial roller direction of individual cooling jackets; and

(15) FIG. 13 control diagrams for controlling a parameter of a rolled stock according to the prior art.

DETAILED DESCRIPTION OF THE FIGURES

(16) The invention will be next described in detail with reference to said FIG. 1 through 12 in the form of embodiments. The same technical elements are designated with the same reference symbols in all of the figures.

(17) FIG. 1 shows cascade control for controlling a parameter of a metal strip, used for example to control its profile or its flatness. The description of FIG. 13 in the introduction of the present description is referred to with respect to the basic operation of cascade control.

(18) Unlike according to the known cascade control shown in FIG. 13, the cascade control according to this invention shown in FIG. 1 is provided with a special actuator 160. The actuator 160 is a cooling jacket which is formed with a circular cross-section. The cooling jacket is placed at a distance against the surface of a roller to be cooled in a roll stand, so that a cooling gap is created between the cooling jacket and the surface of the roller for the cooling passing through it. The cooling jacket is formed in its cross-section preferably complementarily to the outer contour or to the cross-section of the roller.

(19) The cooling jacket according to the invention is formed as a variable and adjustable cooling jacket with the aid of an actuator 165 in its effective length in the circumferential direction of the roller. By means of a signal s which is generated by the controller 150, the effective length of the cooling jacket 160 is suitably adjusted in the circumferential direction of the roller depending on the heat flow control deviation e{dot over (Q)}. Suitably means in this context that the heat flow control deviation e{dot over (Q)} is as close to zero as possible. The heat flow control deviation e{dot over (Q)} is in its turn dependent on the parameter control deviation eP, as described in the introduction with reference to FIG. 13. With the control according to the invention, in addition to the heat flow control deviation, the parameter control deviation should be also zero as much as possible.

(20) For this purpose, the effective length of the cooling jacket 160 is increased in the circumferential direction of the roller when the target value {dot over (Q)}.sub.abtarget of the heat flow to be output from the roller is greater than the measured value {dot over (Q)}.sub.abactual and vice versa. On the other hand, the effective length of the cooling jacket in the circumferential direction can remain unchanged when the target value {dot over (Q)}.sub.abtarget of heat flow to be output from the roller is equal to the actual value {dot over (Q)}.sub.actual of the heat flow that is output.

(21) FIG. 2 shows a first embodiment of the cooling jacket according to the invention. Accordingly, the cooling jacket 160 is provided with at least a first and a second cooling segment 161 and 162, which are respectively provided with a first cross-section in the form of a section of circular arc for covering a surface area of the roller.

(22) With the aid of the actuator 165, which is designed in the first variant shown in FIG. 2 as a hydraulic cylinder, the two cooling jacket segments 161, 162 can be moved relative to each other in the circumferential direction of the roller 300 according to the control signal s in order to adjust in this manner the entire effective length b of the cooling jacket 160 in a suitable manner in accordance with the control signal s. The effective length b is in the present description always represented by the angle or by the corresponding length of the arc shown in FIG. 2 and in the following figures. The reference symbol A designates the rotational axis of the roller 300 and the reference symbol D designates its rotational direction during the rolling of the rolled stock 200, which is moved in the rolling direction WR.

(23) It can be also seen from FIG. 2 that both cooling jackets 161, 162 are always arranged at a distance to the outer surface of the roller 300, so that a cooling gap is formed between the cooling jacket segments and the surface of the roller 300. To this cooling gap 180 is supplied a coolant 400, which flows through the cooling gap in or counter to the direction which is indicated by the arrow. The cooling effect is essentially determined by the effective length b of the cooling jacket 160 or of the cooling jacket element 161, 162. The greater the effective length b, the greater is also the cooling output, which is to say the more heat can be discharged from the roller 300. FIG. 2 shows the first embodiment of the cooling jacket 160 with a relatively short effective length b, because both cooling jacket elements 161, 162 are largely or greatly overlapping in the position which is shown in FIG. 2.

(24) FIG. 3, on the other hand, shows the first embodiment with the first variant for the actuator 165 in a working position, in which the two cooling jacket elements 161 and 162 are much less overlapping compared to the working position shown in FIG. 2, and in which the effective length b is therefore increased.

(25) FIG. 4 shows the first embodiment of the cooling jacket with a second variant for the actuator 165. Unlike in the first variant, the actuator or the displacement device 165 according to FIG. 4 has a more complicated construction. The displacement device comprises a rotatably mounted wheel 165-1, as well as an associated drive device 165-2 for rotatable driving of the wheel. The wheel 165-1 is in turn coupled to the second cooling jacket segment 162, for example with a coupling element 165-3, with frictional engagement or with positive engagement in such a way that a rotational movement of the wheel 165-1 causes shifting of the second cooling jacket 162 in the circumferential direction of the roller 300 relative to the cooling jacket segment 161. FIG. 4 shows the cooling jacket 160 with the two cooling jackets 161, 162 in a working position with a relatively short effective length.

(26) FIG. 5, on the other hand, shows the first embodiment of the cooling jacket with the second variant of the displacement device 165 in a working position with an increased effective length b.

(27) In all FIGS. 2 through 5, the first cooling jacket segment 161 is arranged in a fixed manner relative to the roller 300 with respect to the first embodiment.

(28) FIG. 6 shows a second embodiment of the cooling jacket 160 according to the invention, which is formed from a flexible material. The actuator 165 is in this case designed as a bending device, or as a winding and unwinding device for adjusting the effective length b of the cooling jacket 160 in the circumferential direction of the roller 300. Specifically, the actuator 165 is used, for example, for winding up with a rolling motion the flexible cooling jacket 160 in order to create a relatively short effective length b of the cooling gap 180.

(29) FIG. 7 shows the cooling jacket 160 having a greater effective length b in comparison to FIG. 6, which was created so that the actuator 165 unwinds the flexible material of the cooling jacket and thus increases the cooling jacket.

(30) FIG. 8 shows a third embodiment of the cooling jacket 160 according to the invention, wherein this embodiment is provided with at least one rotatable flap, although typically with a plurality of rotatable flaps 163. An actuator 165, not shown here, is in this case designed for adjusting the effective length of the cooling jacket 160 in the circumferential direction of the roller 300 by opening or closing the at least one of the flaps 163 in accordance with the control signal s.

(31) The respective FIGS. 8 through 11 show different variants for influencing the effective length b of the cooling jacket 160 by individually opening individual flaps 163. The flaps form a part of the surface of the cooling jacket 160 and they therefore delimit at least in the closed state the cooling gap 180.

(32) FIG. 12 shows a top view of the roller 300 with an installed cooling jacket 160. It can be seen that the cooling jackets 160 consists of a plurality N of partial cooling jackets, wherein in this case N=7, namely of partial cooling jackets 160-n, wherein n=1 through n=N, which are arranged next to each other in the axial direction of the roller 300 to be cooled. The actuator 165, not shown here in FIG. 12, is designed for a suitable individual adjustment of the effective length of each individual jacket 160-n of n cooling jackets in the circumferential direction of the roller 300 in accordance with the control deviation e{dot over (Q)}. The heat flow control deviation e{dot over (Q)} represents in generaland thus also in the embodiment shown in FIG. 12the distribution of the heat flow to be output by the roller 300 in the axial direction of the roller, or in the width direction B of the rolled material 200. The widths of the individual partial cooling jackets 160-n in the axial direction can be individually different; they are indicated in FIG. 12 by the reference symbols a, b, c and d.

(33) The partial cooling jackets 160-n can also be provided with a common cooling segment 161, which is designed to be integrated in one piece so that only the second cooling jacket segments 162-n can be variably adjusted in their effective length in the circumferential direction of the roller 300, as indicated by vertical double arrows in FIG. 12.

(34) However, FIG. 12 is not limited only to the design of the cooling jackets 160 according to the first embodiment. Instead, the basic principle illustrated in FIG. 12 of the effective length b over the axial lengths of the rollers can be realized in all three embodiments used for the cooling jackets 160 as described in the present description.