Patent Application
20100005844
The present invention relates to a controlling arrangement for a rolling stand. It also relates to a computer program for a software-programmable controlling arrangement for a rolling stand. Furthermore, the present invention relates to a rolling arrangement. Finally, the present invention relates to a rolling mill with a number of rolling arrangements.
Various controlling arrangements for rolling stands are known. The most important controlling arrangements are roll gap controls and rolling force controls. A prerequisite for both controls is that the actuating element by means of which the roll gap of the rolling stand can be set is adjustable under load.
In the case of roll gap control, an actuating distance setpoint value is fed to a position controller. The actuating distance setpoint value is set such that the roll gap is suitably set. The actuating distance actual value is detected by means of a suitable detecting element and likewise fed to the position controller. From the values fed to it, the position controller determines a manipulated variable, on the basis of which the actuating distance of the actuating element can be changed, so that the actuating distance actual value is brought closer to the actuating distance setpoint value. The position controller outputs the manipulated variable to the actuating element.
During the rolling of the rolled stock, the rolling stand springs up on account of the rolling force exerted on the rolled stock. To compensate for this springing, it is known to detect the rolling force (more precisely: the rolling force actual value), to determine the springing of the rolling stand from the rolling force actual value and to correct the actuating distance setpoint value in such a way as to compensate for the springing of the rolling stand. If the rolling force increases, the actuating distance setpoint value is therefore changed in such a way that the correction of the actuating distance setpoint value counteracts the increase in the roll gap caused by the springing.
The controlling arrangement described above operates entirely satisfactorily if the rolls by means of which the rolled stock is rolled are exactly round and are mounted exactly centrally. However, these two conditions are not generally exactly ensured. There is therefore generally an eccentricity and/or an out-of-roundness. Only the eccentricity is discussed in more detail below. However, the problems entailed by out-of-roundness are equivalent to the problems entailed by eccentricity.
If, for example, the roll gap is reduced on account of an eccentricity, the rolled stock is rolled more strongly in the roll gap. An increased rolling force is required for this. If—in a way corresponding to the procedure described above for compensating for instances of springing of the rolling stand—the increased rolling force is interpreted as springing of the stand, the roll gap is reduced even further by the procedure
described above, in addition to the reduction of the roll gap caused by the eccentricity. The eccentricity errors of the rolls are therefore imposed on the rolled stock to an increased extent. If the rolling force increases as a result of eccentricity, the actuating distance setpoint value must therefore be varied in such a way that the roll gap is opened up, in order to compensate for the eccentricity-induced reduction of the roll gap. The required variation of the actuating distance setpoint value in cases of eccentricity-induced rolling force changes is therefore diametrically opposed to the required changing of the actuating distance setpoint value that is attributable to other changes of the rolling force.
In the prior art, it is known in the case of a roll gap controller to determine the eccentricity of the rolls from the periodic fluctuations of, for example, the rolling force or the tension in the rolled stock upstream or downstream of the rolling stand under consideration, and to compensate for the eccentricity of the rolls by corresponding pre-control of the actuating distance setpoint value. Only the remaining fluctuation of the rolling force is regarded as springing of the rolling stand and is correspondingly corrected. It is of decisive significance in the case of this procedure that the changing of the actuating distance setpoint value brought about by eccentricity-induced changes of the rolling force on the one hand and brought about by changes of the rolling force due to other causes on the other hand are contrary. As already mentioned, the corresponding procedures are known. Purely by way of example, reference is made to U.S. Pat. No. 4,656,854 A, U.S. Pat. No. 4,222,254 A and U.S. Pat. No. 3,709,009 A.
In the case of rolling force control, a rolling force setpoint value and a rolling force actual value are fed to a rolling
force controller. From the values fed to it, the force controller determines a manipulated variable, on the basis of which the actuating distance of the actuating element can be changed, so that the rolling force actual value is brought closer to the rolling force setpoint value.
In theory, an eccentricity of the rolls is not critical in the case of rolling force control. This is so because if, for example, an eccentricity briefly leads to a reduction in the roll gap, and consequently to an increase in the rolling force actual value, the actuating distance of the actuating element is changed in such a way that the roll gap is opened up, and therefore the rolling force actual value falls again.
In practice, however, the detection of the rolling force actual value is falsified by frictional forces which occur in the actuating element and in the rolling stand. Furthermore, the dynamics of the rolling force controls are too low, in particular at high rolling speeds, to compensate quickly enough for the eccentricity-induced rolling force fluctuations.
DE 198 34 758 A1 discloses a controlling arrangement for a rolling stand which has a force controller and a position controller. During the operation of the controlling arrangement, the force controller is fed a rolling force setpoint value and a rolling force actual value.
From the values fed to it, the force controller determines an actuating distance correction value. The actuating distance correction value and an actuating distance actual value of an actuating element are fed to the position controller. From the values fed to it, the position controller determines a manipulated variable, on the basis of which the actuating distance of the actuating element is changed. The manipulated variable is output to the actuating element.
According to various embodiments, possibilities can be provided by means of which eccentricities can be effectively compensated even in the case of rolling force control.
According to an embodiment, in a controlling arrangement for a rolling stand, the controlling arrangement has a force controller and a position controller, which is subordinate to the force controller, during the operation of the controlling arrangement,—the force controller is fed a rolling force setpoint value and a rolling force actual value and, from the rolling force setpoint value and the rolling force actual value, the force controller determines an actuating distance correction value,—the actuating distance correction
value, an eccentricity compensation value, which is different from the actuating distance correction value, and an actuating distance actual value of an actuating element are fed to the position controller,—from the values fed to it, the position controller determines a manipulated variable, on the basis of which the actuating distance of the actuating element is changed, and which is output to the actuating element, so that the controlling arrangement brings about force control of the rolling stand during operation.
According to a further embodiment, the force controller may have integral action, in particular is formed as a controller with an integral component. According to a further embodiment, in addition to the values that are the actuating distance correction value, eccentricity compensation value and actuating distance actual value, the position controller may be fed a basic actuating distance setpoint value during the operation of the controlling arrangement. According to a further
embodiment, the position controller can be formed as a purely proportional controller. According to a further embodiment,
the controlling arrangement may have a rolling force actual value determinator, to which variables that are characteristic of the rolling force actual value are fed to the controlling arrangement during operation and by which the rolling force actual value is determined from the characteristic variables. According to a further embodiment, the controlling arrangement can be formed as a software-programmable controlling arrangement and the force controller and the position controller can be realized as software blocks. According to a further embodiment, the rolling force actual value determinator may also be realized as a software block.
According to another embodiment, a computer program for a controlling arrangement as described above may comprise machine code which can be executed directly by the controlling arrangement and the execution of which by the controlling arrangement may have the effect that the controlling arrangement realizes a force controller and a position controller, which act as described above.
According to a further embodiment, the execution of the machine code by the controlling arrangement additionally may bring about the effect that the controlling arrangement realizes a rolling force actual value determinator, wherein the controlling arrangement has a rolling force actual value determinator, to which variables that are characteristic of the rolling force actual value are fed to the controlling arrangement during operation and by which the rolling force actual value is determined from the characteristic variables.
According to yet another embodiment, a data carrier with a computer program as described above may be stored on the data carrier in a machine-readable form.
According to yet another embodiment, a rolling arrangement may have a rolling stand, wherein the rolling stand has an actuating element, by means of which a roll gap of the rolling stand can be set under load, wherein the rolling stand has detecting elements, by which an actuating distance actual value of the actuating element is detected during the operation of the rolling arrangement and at least one first variable that is characteristic of a rolling force actual value with which a rolled stock is rolled in the roll gap of the rolling stand during the operation of the rolling arrangement is detected, and a controlling arrangement as described above and wherein during the operation of the rolling arrangement, the at least one first variable or a rolling force actual value derived from the first variable is fed to the force controller of the controlling arrangement, the actuating distance actual value is fed to the position controller of the controlling arrangement and the manipulated variable determined by the position controller of the controlling arrangement is output to the actuating element.
According to yet another embodiment, a rolling mill may comprise a number of rolling arrangements that are passed through one after the other by a rolled stock during the operation of the rolling mill, wherein the rolling arrangement that is passed through last by the rolled stock during the operation of the rolling mill is formed as described above.
Further advantages and details emerge from the following description of an exemplary embodiment in conjunction with the basic drawing, in which
According to various embodiments, the controlling arrangement has a force controller and a position controller, which is subordinate to the force controller. During the operation of the controlling arrangement, the force controller is fed a rolling force setpoint value and a rolling force actual value. From the rolling force setpoint value and the rolling force actual value, the force controller determines an actuating distance correction value. The actuating distance correction value, an eccentricity compensation value, which is different from the actuating distance correction value, and an actuating distance actual value of an actuating element are fed to the position controller. From the values fed to it, the position controller determines a manipulated variable, on the basis of which the actuating distance of the actuating element is changed. The manipulated variable is output by the position controller to the actuating element. The components of the controlling arrangement interact in such a way that the controlling arrangement brings about force control of the rolling stand during operation.
If the controlling arrangement is software-programmable, the computer program according to an embodiment comprises machine code which can be executed directly by the controlling arrangement. The execution of the machine code by the controlling arrangement has the effect that the controlling arrangement realizes a force controller and a position controller, the two controllers acting in the way described above. The computer program may be stored on a data carrier.
According to various embodiments, the rolling arrangement has a rolling stand. The rolling stand has an actuating element, by means of which a roll gap of the rolling stand can be set under load. The rolling stand has detecting elements, by which an actuating distance actual value of the actuating element is detected during the operation of the rolling arrangement and at least one first variable that is characteristic of a rolling force actual value with which a rolled stock is rolled in the roll gap of the rolling stand during the operation of the rolling arrangement is detected. The rolling arrangement also has a controlling arrangement, such as that described above. During the operation of the rolling arrangement, the at least one first variable or a rolling force actual value derived from the first variable is fed to the force controller of the controlling arrangement. The actuating distance actual value is fed to the position controller of the controlling arrangement. The manipulated variable determined by the position controller of the controlling arrangement is output to the actuating element.
The rolling arrangement according to various embodiments may be used in particular in a rolling mill which has a number of rolling arrangements that are passed through one after the other by a rolled stock during the operation of the rolling mill. In principle, the rolling arrangement according to
various embodiments may in this case be any of the rolling arrangements of the rolling mill. However, the rolling arrangement according to various embodiments is generally the rolling arrangement that is passed through last by the rolled stock during the operation of the rolling mill.
The procedure according to various embodiments has the effect that the eccentricity of the rolls of the rolling stand can be compensated by corresponding pre-control of the actuating element, although the controlling arrangement ultimately brings about a force control of the rolling stand.
The force controller preferably has integral action. In particular, it may be formed as a controller with an integral component. By this configuration, the force controller operates particularly effectively.
In addition to the values that are the actuating distance correction value, eccentricity compensation value and actuating distance actual value, it is possible to feed the position controller a basic actuating distance setpoint value during the operation of the controlling arrangement. This procedure has the effect that the actuating element is set at least substantially to a meaningful initial value already at the beginning of the operation of the rolling arrangement.
The position controller is preferably formed as a purely proportional controller. By this configuration, higher-quality control of the rolling force is obtained.
It is possible to feed the controlling arrangement the rolling force actual value directly as such. Alternatively, the controlling arrangement may have a rolling force actual value determinator, to which variables that are characteristic of the rolling force actual value are fed to the controlling arrangement during operation. In this case, the rolling force actual value is determined by the rolling force actual value determinator from the characteristic variables.
The controlling arrangement may be formed as a software-programmable controlling arrangement. In this case, the force controller and the position controller are realized as software blocks. If the controlling arrangement has the aforementioned rolling force actual value determinator, the rolling force actual value determinator is also preferably formed as a software block.
With respect to the computer program, the execution of the machine code by the controlling arrangement preferably brings about the effect that the controlling arrangement also realizes the rolling force actual value determinator.
The computer program may, in particular, take the form of a computer program product.
According to
The rolling stand 2 has work rolls 3. The work rolls 3 form a roll gap 4 between them. In the roll gap 4, a rolled stock 5 is rolled. The rolling operation may be cold rolling or hot rolling.
According to
alternatively have some other form, for example take the form of a rod or tube.
The rolled stock 5 may consist, for example, of steel, aluminum or copper. Alternatively, the rolled stock 5 may—irrespective of its form—consist of some other material, for example of plastic.
The roll gap 4 can be set by means of an actuating element 6. According to
The rolling arrangement 1 also has a controlling arrangement 7. During the operation of the rolling arrangement 1, the rolling stand 2 is controlled by the controlling arrangement 7. For this purpose, the controlling arrangement 7 has a force controller 8 and a position controller 9. The position controller 9 is subordinate here to the force controller 8. During the operation of the rolling arrangement 1 (or during the operation of the controlling arrangement 7), the rolling stand 2 (including its actuating element 6) and the controlling arrangement 7 operate as follows:
A rolling force setpoint value F* and a rolling force actual value F are fed to the force controller 8. The rolled stock 5 is rolled in the roll gap 4 of the rolling stand 2 with a rolling force corresponding to the rolling force actual value F.
The rolling force setpoint value F* may, for example, be generated by the controlling arrangement 7 by means of an internal rolling force setpoint value determinator. However, the rolling force setpoint value determinator is not represented in
The rolling force actual value F must be directly or indirectly detected by means of suitable detecting elements 10. According to
F=p1A1−p2A2,
where A1 and A2 are the areas A1, A2 of a piston 14 of the hydraulic cylinder unit 6 that bound the working chambers 11, 12 of the hydraulic cylinder unit 6. If the actuating element 6 were formed differently, the rolling force actual value F could, however, also be detected or determined in some other way. In particular, it is possible to detect the rolling force actual value F directly by means of a load cell. This procedure is possible irrespective of whether or not the actuating element 6 is realized as a hydraulic cylinder unit. In this case, the force controller 8 is fed the detected variable directly, since the detected variable in this case corresponds directly to the rolling force actual value F.
The force controller 8 determines from the rolling force setpoint value F* and the rolling force actual value F an actuating distance correction value δs1*. The force controller 8 feeds the actuating distance correction value δs1* to the position controller 9.
The position controller 9 accepts the actuating distance correction value δs1*. As further input values, the position controller 9 also accepts an actuating distance actual value s and an eccentricity compensation value δs2*. Furthermore, the position controller 9 may be additionally fed a basic actuating distance setpoint value s*. However, this is only optionally the case.
From the values fed to it, δs1*, δs2*, s and optionally s*, the position controller 9 determines a manipulated variable δq. The manipulated variable δq is output by the position controller 9 to the actuating element 6. The actuating distance of the actuating element 6 is changed on the basis of the manipulated variable δq. In the case of the configuration of the actuating element 6 as a hydraulic cylinder unit, the manipulated variable δq may be, for example, an amount of oil that is pumped per unit of time by an oil pump that is not represented into the working chamber 11 of the hydraulic cylinder unit, or let out of it.
The actuating distance actual value s is detected by means of a suitable detecting element 10′ known per se of the rolling
arrangement 1 and fed by this detecting element 10′ to the position controller 9. Such detecting elements 10′ are generally known.
The eccentricity variation can be determined within the controlling arrangement 7 independently. Corresponding
detecting devices are known in the prior art, see, for example, the aforementioned U.S. Pat. Nos. 4,656,854, 4,222,254 and 3,709,009. Alternatively, the eccentricity variation may be fed to the controlling arrangement 7 from the outside. What is decisive is that variables E, α, which describe the variation in the eccentricity, are known to the controlling arrangement 7. The variables may be, for example, an amplitude E of the eccentricity and a phase position α of the eccentricity. The phase position α may optionally be a vector which includes for each of the rolls 3, 15 of the rolling stand 2 an own frequency and an own individual phase position, that is to say both for each of the work rolls 3 and for each of the backing rolls 15.
According to
Other methods for determining the eccentricity compensation value δs2*—in conjunction with roll gap controls—are also known in the prior art. For example, it is known to determine (at least) a frequency of the eccentricity (and consequently also of the eccentricity compensation value δs2*) from the speed of the drive motor for the work rolls 3 and to correct the amplitude and phase position of the variation over time of the eccentricity compensation value δs2* until the eccentricity is completely eliminated by the control. Which method is used for determining the eccentricity compensation value δs2* is at the discretion of a person skilled in the art. What is decisive is that the compensation value determinator 16 correctly determines the respective eccentricity compensation value δs2* and feeds it to the position controller 9.
The force controller 8 operates in such a way that, with a constant rolling force setpoint value F*, it keeps correcting the actuating distance correction value δs1* until the rolling force actual value F corresponds to the rolling force setpoint value F*. In particular, if there is an increase in the rolling force actual value F, the force controller 8 does not make the work rolls 3 of the rolling stand 2 move toward one another, as would be the case when compensating for springing of the rolling stand 2. Rather, in such a case the force controller 8 makes the work rolls 3 open up, in order to adapt the rolling force actual value F to the rolling force setpoint value F*.
The force controller 8 should preferably have integral action. For this purpose, the force controller 8 may, for example, be formed as an I controller, as a PI controller or as a PID controller. The abbreviations P, I and D stand here for the conventional designations proportional, integral and differential. The force controller 8 may alternatively also be formed as a different controller with an integral component. The position controller 9 is preferably formed as a purely P controller. It may comprise compensation for a zero-point error and linearization of the actuating element behavior.
The controlling arrangement 7 according to various embodiments may be formed as a hardware circuit. However, the controlling arrangement 7 according to
The controlling arrangement 7 of
The computer program 19 comprises machine code 21, which can be executed directly by the controlling arrangement 7. The execution of the machine code 21 by the controlling arrangement 7 has the effect that the controlling arrangement 7 realizes at least the force controller 8 and the position controller 9 as software blocks 22. If the controlling arrangement 7 has further components, for example the rolling force actual value determinator 13 and/or the compensation value determinator 16, the execution of the machine code 21 by the controlling arrangement 7 preferably also brings about the realization of these components 13, 16 as software blocks 22. The force controller 8 realized as software block 22, the position controller 9 realized as software block 22, and optionally the further components 13, 16 of the controlling arrangement 7 realized as software blocks 22, act of course in the way described in detail above in conjunction with
A rolling mill is now described in conjunction with
With the procedure according to various embodiments, superior force-controlled operation of the rolling arrangement 1 can be achieved. In particular, eccentricities can be eliminated by the control considerably better than is possible in the prior art.
The above description serves exclusively for explaining the present invention. On the other hand, the scope of the present invention is to be determined exclusively by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2007 003 243.0 | Jan 2007 | DE | national |
This application is a U.S. National Stage Application of International Application No. PCT/EP2008/050615 filed Jan. 21, 2008, which designates the United States of America, and claims priority to German Application No. 10 2007 003 243.0 filed Jan. 23, 2007, the contents of which are hereby incorporated by reference in their entirety.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2008/050615 | 1/21/2008 | WO | 00 | 7/17/2009 |
