Simple pre-control of a wedge-type roll-gap adjustment of a roughing stand

Abstract

A plurality of flat metal items to be rolled (3) are fed to a plurality of rolling stands (1, 2) of a rolling installation, one after the other over a feed path (4). The items (3) are rolled by the rolling stands (1, 2) past which they are fed. In the rolling stands (1, 2), the flat item to be rolled (3) is first rough-rolled in at least one roughing pass with a wedge-type roll gap adjustment (ds) and then finish-rolled in finishing passes. After the finish-rolling of the flat item, a thickness taper (dd) that is present in the respective finish-rolled flat item is recorded by measuring instruments. The thickness taper (dd) is compared with a target taper (dZ). On the basis of a deviation of the thickness taper (dd) from the target taper (dZ) and the wedge-type roll gap adjustment (ds), a new wedge-type roll gap adjustment (ds) is determined for the at least one roughing pass. The wedge-type roll gap adjustment (ds) for the at least one roughing pass for the next flat item to be rolled (3) is set to correspond to the newly determined value of the wedge-type roll gap adjustment (ds), so that the next flat item to be rolled (3) is rough-rolled in the at least one roughing pass with the newly determined value of the wedge-type roll gap adjustment (ds).

Claims

1. An operating method for a rolling mill processing in succession a plurality of flat items of metal rolling stock, the method comprising: feeding a first flat item of the plurality of flat items through a plurality of roll stands of the rolling mill via a first feed path; roughing down the first flat item in at least one stand of the plurality of roll stands during at least one roughing pass with a first value of a wedge setting then finish-rolling the roughed down first flat item in finishing passes; registering a first thickness wedge produced for the first flat item after the finish-rolling of the first flat item; comparing the first thickness wedge of the first flat item with a first target wedge, and determining a deviation of the first thickness wedge from the first target wedge; based on the deviation and on the first value of the wedge setting, determining a new value of the wedge setting for the at least one roughing pass; adjusting the wedge setting in the course of the at least one roughing pass in accordance with the new value of the wedge setting for a next flat item of the plurality of flat items to be rolled next, so that the next flat item is roughed down in the at least one roughing pass with the new value of the wedge setting; and during the roughing down of the plurality of flat item in one of the roll stands, placing lateral guides and/or edgers against the flat items in front or upstream of and/or behind or downstream of the roll stand, such that the lateral guides and/or edgers exert transverse forces on the respective flat items of rolling stock for preventing a saber-type formation in the rolling stock in the course of roughing down; wherein the adjusting of the wedge setting is such that the wedge setting is proportional to the thickness wedge existing in the finish-rolled respective flat item.

2. The operating method as claimed in claim 1, wherein the wedge setting is adjusted such that the wedge setting increases monotonically with the ratio of a mean rolling-stock thickness of the respective flat item after the roughing down and after the finish-rolling.

3. The operating method as claimed in claim 1, further comprising controlling roll alignment during the rolling of a respective flat item.

4. The operating method as claimed in claim 1, further comprising: feeding a second plurality of flat items of rolling stock in succession to the plurality of roll stands via a second feed path; roughing down a first flat item of the second plurality of flat items of rolling stock by at least one roughing pass having a second value for the wedge setting, and then finish-rolling the second flat item in finishing passes; wherein the finish-rolling of the respective second flat item of rolling stock causes a second thickness wedge to exist in the finish-rolled respective second flat item, and registering the second thickness wedge by applied metrology; comparing the second thickness wedge with a second target wedge to calculate a deviation of the second thickness wedge from the second target wedge; based on the deviation and on the second value of the wedge setting, determining a new value for the second wedge setting for the at least one roughing pass; and adjusting the wedge setting in the course of the at least one roughing pass for second flat item of the second plurality of flat items to be rolled next in accordance with the new value of the wedge setting, so that the next second flat item new value of the wedge setting.

5. A non-transient computer-readable medium product incorporating a computer program code configured to control a rolling mill, the program code configured, when executed by a control device, to operate the rolling mill in accordance with the operating method as claimed in claim 1.

6. A control device of a rolling mill, wherein the control device incorporates the computer program of the computer program product claimed in claim 5.

7. A rolling mill for processing a plurality of flat items of metal rolling stock, the rolling mill comprising: the rolling mill including a first feed path, via which a plurality of first flat items of rolling stock made of metal are fed in succession to a plurality of roll stands of the rolling mill; the rolling mill includes a plurality of roll stands configured for rolling the plurality of flat items, wherein a first flat item of the plurality of flat items is roughed down in at least one stand of the plurality of roll stands in at least one roughing pass with a first value of a wedge setting and then the first flat item is finish rolled in finishing passes; the rolling mill including a thickness-measuring device configured to measure a thickness of the first flat item after the finish-rolling of the first flat item, wherein a first thickness wedge in the finish-rolled first flat item is registered by applied metrology; wherein the rolling mill includes, in front or upstream of and/or behind or downstream of the roll stand, for carrying out the at least one roughing pass, lateral guides and/or edgers which, during the roughing down of the first flat item, are placed against this roll stand to exert transverse forces on the first flat item, which forces are directed and applied to prevent a saber-type formation in the course of the roughing down; and a control device configured to control operation of the rolling mill including the roll stands so as to adjust the first wedge setting in the course of the at least one roughing pass in accordance with a new value of the wedge setting, for a next flat item of the plurality of flat items to be rolled next, so that the next flat item is roughed down in the at least one roughing pass with the new value of the wedge setting, wherein the new value is determined by comparing the first thickness edge of the first flat item with a first target wedge, and determining a deviation of the first thickness wedge from the first target wedge; based on the deviation and on the first value of the wedge setting, determining the new value of the wedge setting for the at least one roughing pass.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a schematic illustration of a rolling mill,

(2) FIG. 2 shows a roll gap of a roughing stand,

(3) FIG. 3 shows a cross section through a flat item of rolling stock,

(4) FIG. 4 shows a section of the rolling mill from above and

(5) FIG. 5 shows a further rolling mill.

DESCRIPTION OF EMBODIMENTS

(6) FIG. 1 shows a configuration of a rolling mill in which a single roughing stand 1 and several finishing stands 2 are present. As a rule, between four and seven finishing stands 2 are present. At least the finishing stands 2 are passed through in succession by flat items of rolling stock 3. The flat items of rolling stock 3 are rolled in the finishing stands 2 in each instance in a single roll pass (finishing pass). The flat items of rolling stock 3 consist of metal, for example steel or aluminum. However, other metals are also possible, for example copper.

(7) In the configuration according to FIG. 1, each finishing stand 2 accordingly carries out a single roll pass. The roughing stand 1 may also carry out several roll passes (roughing passes), in an oscillating manner. The present invention will be elucidated below in conjunction with this frequently encountered configuration, that is, with a single roughing stand 1 and several finishing stands 2. The roughing stand 1 carries out several roll passes, oscillating, and each finishing stand 2 carries out a single roll pass. However, the present invention is not restricted to this configuration.

(8) For instance, several roughing stands 1 might be present, which are passed through in succession by the flat items of rolling stock 3. In this case, it is possible that each roughing stand 1 carries out one roughing pass. Alternatively, in this case the roughing stands 1 may also be passed through by the flat items of rolling stock 3 several times, oscillating. In some cases, a single roughing stand 1 might also be present, which is passed through by the flat items of rolling stock 3 in only a single roll pass. In both cases the finishing stands 2 would continue to be passed through in succession by the flat items of rolling stock 3, each finishing stand 2 respectively carrying out a single roll pass. Moreover, in the case of several roughing passes per respective flat item of rolling stock 3, the respective flat item of rolling stock 3 is not rolled, that is, not reduced in its thickness in some of the roughing passes.

(9) But it is also possible that only a single roll stand is present, which is passed through by the flat items of rolling stock 3 several times, oscillating. In this case, all the roll passes that is to say, both the roughing passes and the finishing passes would be carried out by the same roll stand.

(10) The flat items of rolling stock 3 are fed in succession to the roll stands 1, 2 via a feed path defining device 4. That device 4 may, for example, take the form of a continuous casting plant with downstream equalizing furnace. Alternatively, the feed path device 4 may take the form of a ferry with a downstream furnace (for example, a tunnel furnace). The device 4 may also take the form of a slab stock with a downstream furnace. Other configurations are also possible.

(11) After the feeding of one of the flat items of rolling stock 3 to the first roll stand 1 of the rolling mill in accordance with the configuration of FIG. 1, after the feeding to the roughing stand 1, the respective flat item of rolling stock 3 is firstly roughed down in the roll stands 1, 2 in respective roll passes. In a roughing stand 1, it is roughed by oscillating in several roughing passes. In a finishing stand 2, it is roughed in a respective finishing pass. In all cases the flat item is then finish-rolled. In particular, the roughing down in the roughing stand 1 is undertaken with a wedge setting ds of the roughing stand 1. During the respective roughing pass, the roughing stand 1 has accordingly been set in such a manner that the roll gap s of the roughing stand 1 extends in the shape of a wedge in accordance with the representation in FIG. 2, viewed over the width b of the roughing stand 1. The roll gap s of the roughing stand 1 accordingly has a wedge setting ds, the wedge setting ds being given by the relationship
ds=sDSsOS(1)

(12) In equation 1, sDS and sOS are the roll gap sDS on the drive side and the roll gap sOS on the operating side of the roughing stand 1. The wedge setting ds has been represented in FIG. 2 in distinctly exaggerated manner, for reasons of better illustration.

(13) The wedge setting ds may be uniformly the same for all roughing passes. Alternatively, the wedge setting ds may have been determined individually from roughing pass to roughing pass. For example, the wedge setting ds of the respective roughing pass may be correlated with the exit-side nominal thickness of the respective roughing pass. In particular, it may be proportional to the exit-side nominal thickness of the respective roughing pass. Other procedures are also possible.

(14) After the roughing passes have been carried out, the finishing passes are carried out. The respective flat item of rolling stock 3 is accordingly finish-rolled in the finishing stands 2 in the finishing passes. If required, the finishing stands 2 may have had a respective wedge setting applied to them during the execution of the respective finishing pass, for example, within the scope of the roll alignment control.

(15) Downstream of the finishing stands 2, and more precisely, downstream of the finishing stand 2 carrying out the last finishing pass, a thickness-measuring device 5 is arranged. By means of the thickness-measuring device 5 a thickness wedge dd which is present in the finish-rolled respective flat item of rolling stock 3 is registered by applied metrology after the finish-rolling of the respective flat item of rolling stock 3. According to FIG. 3, the thickness wedge dd is expresses in a manner analogous to the wedge setting ds for example by the relationship
dd=dDSdOS(2)

(16) In Equation 2, dDS and dOS are the rolling-stock thickness dDS on the drive side and the rolling-stock thickness dOS on the operating side of the flat rolling stock 3 on the exit side of the finishing stand 2 carrying out the last finishing pass. The thickness wedge dd has been represented in FIG. 3, in a manner analogous to the wedge setting ds in a distinctly exaggerated manner, for reasons of better illustration.

(17) It is also possible to determine the thickness wedge dd on the basis of other variables. For example, it is customary to measure the rolling-stock thicknesses dDS and dOS not directly at the lateral edges of the flat rolling stock 3 but rather at a distance from the lateral edges. The distance may amount to 25 mm or 40 mm, for example. A different sensible value may also be used by way of distance from the lateral edges. It is also possible to register the rolling-stock thickness at several places over the width of the rolling stock and to optimize, on the basis of the registered rolling-stock thicknesses, for example a parameterized description of the rolling-stock thickness as a function of location, viewed in the width direction. In this case, one of the parameters of the parameterized description, which is characteristic of the asymmetry of the rolling-stock thickness, can be drawn upon for the purpose of ascertaining the thickness wedge dd. Other procedures are also possible.

(18) The thickness-measuring device 5 is, according to FIG. 1, connected to a control device 6 in a manner enabling transfer of data. The control device 6 has been programmed with a control program 7. The control program 7 comprises machine code 8 that can be executed by the control device 6. The execution of the machine code 8 by the control device 6 causes the control device 6 to operate the rolling mill in accordance with the operating method described above and also elucidated further below. In particular, the control device 6 controls the roll stands 1, 2 and the transport of the flat items of rolling stock 3 through the rolling mill. The control device 6 preferentially continues to implement an RAC during the rolling of the respective flat item of rolling stock 3.

(19) Within the scope of the execution of the machine code 8 the control device 6 accepts from the thickness-measuring device 5 the measured values thereof, in particular the thickness wedge dd or the rolling-stock thicknesses dDS, dOS on the drive side and on the operating side. On the basis of the deviation of the thickness wedge dd from a target wedge dZ, where appropriate with additional utilization of further variables such as, for example, the wedge setting ds and/or a rolling-stock width, the control device 6 ascertains a change dds of the wedge setting ds. The control device 6 then changes the wedge setting ds by the change dds of the wedge setting ds. The control device 6 consequently ascertains a (new) wedge setting ds. For example, an ascertainment according to the relationship
ds=ds+dds(3)

(20) can be undertaken. The newly ascertained wedge setting ds applies to the flat item of rolling stock 3 to be rolled next. The flat item of rolling stock 3 to be rolled next is accordingly roughed down in the roughing passgenerally, in the at least one roughing passwith the new wedge setting dsfor example, according to Equation 3.

(21) The sense and purpose of the procedure that has been elucidated is that for the flat item of rolling stock 3 to be rolled next the deviation of the thickness wedge dd from the target wedge dZ has at least a smaller value than for the last, already rolled flat item of rolling stock 3. In the optimal case, the thickness wedge dd of the flat item of rolling stock 3 rolled next is even equal to the target wedge dZ. Therefore the control device 6 ascertains the change dds of the wedge setting ds in such a manner that the change dds of the wedge setting ds counteracts the deviation.

(22) In the simplest case, the control device 6 ascertains the change dds of the wedge setting ds in accordance with the relationship
dds=k(dddZ)(4)

(23) In the simplest case, the change dds of the wedge setting ds is accordingly proportional to the deviation of the thickness wedge dd existing in the finish-rolled respective flat item of rolling stock 3 from the target wedge dZ. k is a suitably chosen proportionality factor in terms of absolute value and sign.

(24) Furthermore, the change dds of the wedge setting ds preferentially increases monotonically, given identical deviation of the thickness wedge dd from the target wedge dZ, with the ratio of a mean rolling-stock thickness D, d of the respective flat item of rolling stock 3 after the roughing down and after the finish-rolling. In this connection, D is the mean rolling-stock thickness of this respective flat item of rolling stock 3 after the roughing down, d is the mean rolling-stock thickness after the finish-rolling. In the simplest case, a simple proportionality ratio is predominant. In this case, the proportionality factor k results as
k=kD/d(5)

(25) In equation 5, k is a further proportionality factor which is independent of the two rolling-stock thicknesses D, d.

(26) A combination of equations 4 and 5 consequently yieldssee also FIG. 1the relationship
dds=kD(dddZ)/d(6)

(27) For the purpose of implementing the procedure last elucidatedthat is to say, the monotonic increase of the change dds of the wedge setting ds with the ratio of the mean rolling-stock thickness D, d of the respective flat item of rolling stock 3 after the roughing down and after the finish-rollingit is necessary that the two rolling-stock thicknesses D, d are known to the control device 6. With respect to the mean rolling-stock thickness D of the respective flat item of rolling stock 3 after the roughing down, this rolling-stock thickness D may be known to the control device 6, for example by reason of the adjustment of the roughing stand 1 in the course of carrying out the last roughing pass of the respective flat item of rolling stock. With respect to the mean rolling-stock thickness d of the respective flat item of rolling stock 3 after the finish-rolling, a registration by the thickness-measuring device 5 or by a different, further thickness-measuring device, not represented in FIG. 1, is preferentially undertaken.

(28) In accordance with the invention, the procedure elucidated above in conjunction with FIGS. 1 to 3 has, moreover, been modified in accordance with FIG. 4.

(29) According to FIG. 4, the rolling mill additionally includes lateral guides 9. According to FIG. 4, the lateral guides 9 are arranged in front, or upstream of, or on the input side of and behind, or downstream of, or on the output side of the roughing stand 1. The lateral guides 9 are placed against the sides of the flat rolling stock 3 during the roughing down of the flat rolling stock 3. The lateral guides 9 exert transverse forces FE, FA on the flat rolling stock 3 on the input side and on the output side. The transverse forces FE, FA prevent, both on the entry side and on the output side, a saber-type formation of the flat rolling stock 3 in the course of roughing down. The lateral guides 9 may be elongated, corresponding to the representation in FIG. 4. Alternatively or additionally, the lateral guides 9 may exhibit, in a manner analogous to the procedure described in WO 2013/174602 A1a roller or a similar element that can be placed against the respective flat item of rolling stock 3 in the transverse direction, so that by means of the roller a transverse force can be exerted on the respective flat item of rolling stock 3.

(30) In the configuration according to FIG. 4, lateral guides 9 are arranged both upstream of and downstream of the roughing stand. In some cases it may be sufficient to arrange one lateral guide 9 only upstream of or downstream of the roughing stand 1. The respective other lateral guide 9 would not be present in this case. Moreover, it is possible to replace the anterior and/or the posterior lateral guide 9, irrespective of whether the respective other lateral guide 9 is present or not by an edger.

(31) The configuration of the rolling mill according to FIG. 5 also corresponds, over long sections, to the configuration of the rolling mill according to FIG. 1. According to FIG. 5, however, the rolling mill includes not only the feed path 4, but also, a further feed path 10. The two feed paths 4, 10 are designated below as first feed path 4 and second feed path 10. Also via the second feed path 10, several flat items of rolling stock 11 are fed in succession to the plurality of roll stands 1, 2. The flat items of rolling stock 3, 11 fed to the roll stands 1, 2 via the respective feed path 4, 10 will be designated below as first flat items of rolling stock 3 and second flat items of rolling stock 11.

(32) The second flat items of rolling stock 11 are rolled in the rolling mill in a manner completely analogous to that for the first items of rolling stock 3. In particular, the second flat items of rolling stock 11 are also rolled by means of the plurality of roll stands 1, 2, the respective second flat item of rolling stock 11 being firstly roughed down by means of the plurality of roll stands 1, 2 in at least one roughing pass with a respective second wedge setting ds and then being finish-rolled in finishing passes.

(33) Moreover, also for the second flat items of rolling stock 11 after the finish-rolling of the respective second flat item of rolling stock 11 a second thickness wedge dd existing in the finish-rolled respective second flat item of rolling stock 11 is registered by applied metrology and supplied to the control device 6. The control device 6 compares the second thickness wedge dd with a second target wedge dZ and ascertains for the respective second flat item of rolling stock 11, on the basis of the deviation of the second thickness wedge dd from the second target wedge dZ and from the second wedge setting ds, a new second wedge setting ds for the at least one roughing pass. The ascertainment can be undertaken in a manner completely analogous to that for the first flat items of rolling stock 3. As also applies for the first flat items of rolling stock 3, the second wedge setting ds in the course of the at least one roughing pass for the second flat item of rolling stock 11 to be rolled next is changed. The second flat item of rolling stock 11 to be rolled next is consequently roughed down in the at least one roughing pass with the new value of the second wedge setting ds.

(34) The crucial circumstance consequently consists in the fact that the ascertainment of the new wedge setting ds and, associated with this, the tracking of the wedge setting ds for the first and second flat items of rolling stock 3, 11 are undertaken independently of one another. Even though the first and second flat items of rolling stock 3, 11 exhibit completely different properties (for example, different chemical compositions, different temperatures, different widths, different rolling-stock thicknesses prior to roughing down, etc.), a reliable tracking of the respective wedge setting ds for the respective flat item of rolling stock 3, 11 to be rolled next can therefore be undertaken.

(35) The distinction between the first feed path 4 and second feed path 10 can be made as needed. In the individual case, it is even possible that the flat items of rolling stock 3, 11 do in fact originate from the same sourcefor example, from a common slab stockprior to being fed to the rolling mill, but pass through paths differing from one another, for example different furnaces.

(36) The present invention impresses, above all, by virtue of its simplicity. This is because no complex modeling of the rolling mill is required. Moreover, no registration of any thickness wedge in the rolling stock 3, 11 is required before the roughing down or between the roughing down and finish-rolling. It is merely necessary to register, after the finish-rolling, the thickness wedge dd then existing in the rolling stock 3, 11, and, on the basis of this thickness wedge dd, to track the wedge setting ds of the at least one roughing pass.

(37) Although the invention has been illustrated and described in detail by means of the preferred exemplary embodiment, the invention is not restricted by the examples disclosed, and other variations may be derived therefrom by a person skilled in the art without departing from the scope of protection of the invention.