U.S. patent application number 16/970078 was filed with the patent office on 2021-02-18 for preventing worn edges when rolling flat rolled products.
The applicant listed for this patent is Primetals Technologies Germany GmbH. Invention is credited to Andrea SCHMIDT, Alexander THEKALE.
Application Number | 20210046529 16/970078 |
Document ID | / |
Family ID | 1000005208522 |
Filed Date | 2021-02-18 |
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United States Patent
Application |
20210046529 |
Kind Code |
A1 |
SCHMIDT; Andrea ; et
al. |
February 18, 2021 |
PREVENTING WORN EDGES WHEN ROLLING FLAT ROLLED PRODUCTS
Abstract
A roll stand (1) having at least one pair of rollers (4, 5)
between which a flat rolled product (2) is located. The rollers (4,
5) can be moved axially in opposite directions. The roll stand (1)
has a bending system (6) for the rollers (4, 5). A controller (8)
of the roll stand (1) uses the bending and the axial movement of
the rollers (4, 5) in order to regulate the roll gap contour as an
adjustment mechanism. Prior to rolling a respective rolled product
(2), the controller determines a respective axial position (x) as
the resulting axial position (x) and sets the axial position as the
axial position (x) of the rollers (4, 5) for the roll stand (1) in
order to roll the next flat rolled product (2). For this purpose,
the controller (8) ascertains how far a specified target roll gap
contour can be approximated for a plurality of axial positions (x)
of the rollers (4, 5) by actuating the adjustment mechanism (6, 7)
while taking into consideration technological boundary conditions
and classifies the axial positions (x) at which a deviation of the
resulting roll gap contour from the target roll gap contour lies
below a specified limit as being permissible. The controller then
removes the axial positions (x) excluded from the plurality of
axial positions (x) classified as being permissible as long as at
least one axial position (x) classified as being permissible still
remains after the excluded axial positions (x) are removed. The
controller (8) determines one of the remaining axial positions (x)
as the resulting axial position (x).
Inventors: |
SCHMIDT; Andrea; (Erlangen,
DE) ; THEKALE; Alexander; (Erlangen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Primetals Technologies Germany GmbH |
Erlangen |
|
DE |
|
|
Family ID: |
1000005208522 |
Appl. No.: |
16/970078 |
Filed: |
February 14, 2019 |
PCT Filed: |
February 14, 2019 |
PCT NO: |
PCT/EP2019/053618 |
371 Date: |
August 14, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B21B 37/42 20130101;
B21B 37/165 20130101; B21B 13/02 20130101 |
International
Class: |
B21B 37/16 20060101
B21B037/16; B21B 13/02 20060101 B21B013/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 9, 2018 |
EP |
18160879.5 |
Claims
1. A method for rolling a flat rolled product in a rolling stand,
wherein the rolling stand has at least one pair of rollers, wherein
the rollers are axially displaceable in opposite directions, the
rolling stand has a bending system for the rollers; the method
comprising: situating the flat rolled product between the two
rollers; operating a control device of the rolling stand for
controlling the rolling gap contour using as adjusting mechanisms
the bending and the axial displacement of the rollers; prior to the
rolling of a respective rolled product, operating the control
device to determine a respective axial position (x) as the
resulting axial position (x) and prescribing the resulting axial
position for the rolling stand as axial position (x) of the rollers
for rolling the next flat rolled product; prior to the rolling of
the respective rolled product, operating the control device to
determine for a plurality of axial positions (x) of the rollers how
far a predetermined target rolling gap contour can be approximated
by actuating the adjusting mechanisms while taking account of
technological boundary conditions, the control device classifies as
permissible those axial positions (x) in which a deviation of the
resulting rolling gap contour from the target rolling gap contour
lies below a predetermined limit; the control device removes
blocked axial positions (x) from the set of the axial positions (x)
classified as permissible insofar as at least one axial position
(x) classified as permissible still remains even after the removal
of the blocked axial positions (x); and the control device
determining one of the remaining axial positions (x) as the
resulting axial position (x).
2. The method as claimed in claim 1, further comprising the rolling
stand has backup rollers in addition to the rollers, and arranging
the rollers in each case between the backup rollers and the rolled
product.
3. The method as claimed in claim 1, wherein at least some of the
rollers are each provided with a contour which is curved in the
manner of a bottleneck.
4. The method as claimed in claim 1, further comprising the control
device determining the resulting axial position (x) on a stochastic
basis.
5. The method as claimed in claim 1, further comprising operating
the control device to assign an evaluation to at least the
remaining axial positions (x) on the basis of an evaluation
criterion, and operating the control device to determine the
resulting axial position (x) on the basis of the evaluation.
6. The method as claimed in claim 5, further comprising the control
device to determine the evaluation on the basis of technological
criteria.
7. The method as claimed in claim 1, further comprising the control
device receives a blocking command from an operator, and the
control device blocks axial positions (x) specified in the blocking
command.
8. The method as claimed in claim 1, further comprising the control
device determining a resulting edge of one of the rollers while
taking into consideration a camber, a thermal crown and/or a wear
of the rollers, and; and the control device blocking those axial
positions (x) in which the resulting edge of one of the rollers
would be positioned on a rolled product edge of the flat rolled
product.
9. The method as claimed in claim 1, further comprising the control
device blocking those axial positions (x) which are situated in a
predetermined region around that axial position (x) in which the
flat rolled product that was rolled immediately beforehand is
rolled.
10. The method as claimed in claim 9, further comprising the
control device blocking those axial positions (x) having spacing
(a) which is situated below the minimum spacing (amin) from that
axial position (x) in which the flat rolled product that was rolled
immediately beforehand is rolled, for a predetermined number of
flat rolled product and then cancelling the block again.
11. A control program for a control device for controlling a
rolling stand, wherein the control program comprises machine code
which can be processed by the control device, wherein the
processing of the machine code by the control device has the effect
that the control device carries out a method as claimed in claim
1.
12. A control device for a rolling stand, wherein the control
device is programmed with a non-transitory control program operable
to carry out a method as claimed in claim 1.
13. A rolling stand for rolling a flat rolled product, wherein the
rolling stand has a pair of rollers; and the flat rolled product is
situated between the two rollers; the rollers are axially
displaceable in opposite directions; the rolling stand has a
bending system for the rollers; the rolling stand for controlling
by a control device as claimed in claim 12.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a 35 U.S.C. .sctn..sctn. 371
national phase conversion of PCT/EP2019/053618, filed Feb. 14,
2019, the contents of which are incorporated herein by reference,
which claims priority of European Patent Application No. 18160879.5
filed Mar. 9, 2018, the contents of which are incorporated by
reference herein. The PCT International Application was published
in the German language.
TECHNICAL FIELD
[0002] The present invention starts from a method for rolling a
flat rolled product in a rolling stand, wherein; the rolling stand
has at least one pair of rollers, the flat rolled product is
situated between the two rollers of the pair, the rollers are
axially displaceable in opposite directions, the rolling stand has
a bending system for the rollers.
[0003] A control device of the rolling stand, which is for
controlling the rolling gap contour, uses the bending and the axial
displacement of the rollers as adjusting mechanisms. Prior to the
rolling of a respective rolled product, the control device
determines a respective axial position as a resulting axial
position and prescribes the axial position for the rolling stand as
an axial position of the rollers for rolling the next flat rolled
product.
[0004] The present invention furthermore starts from a
non-transitory control program for a control device for controlling
a rolling stand, wherein the control program comprises machine code
which can be processed by the control device, and wherein the
processing of the machine code by the control device has the effect
that the control device carries out such a method.
[0005] The present invention furthermore starts from a control
device for a rolling stand, wherein the control device is designed
such that in operation it carries out such a method, in particular
is programmed with such a control program.
[0006] The present invention furthermore starts from a rolling
stand for rolling a flat rolled product, the rolling stand has at
least one pair of rollers, the flat rolled product is situated
between the two rollers, the rollers are axially displaceable in
opposite directions, the rolling stand has a bending system for the
rolls, and wherein the rolling stand is controlled by such a
control device.
PRIOR ART
[0007] WO 2006/000 290 A1 discloses a method of the type stated at
the outset. In this method, the bending of the rollers or the
displacement of the rollers are varied cyclically.
SUMMARY OF THE INVENTION
[0008] The quality of the surface and the contour of the rolled
product transversely with respect to the rolling direction are
decisive characteristics for a flat rolled product. As a rule,
further processing steps which occur after the rolling make certain
demands on the maintaining in particular of a target contour of the
flat rolled product, that is the thickness profile as a function
over the width of the flat rolled product.
[0009] A key influencing factor for the contour of the flat rolled
product is the contour of the surfaces of the rollers of the
rolling stand. This contour is composed substantially of three
component parts, the roller camber of a respective roller, the
thermal expansion of the respective roller and the wear of the
respective roller. Particularly the wear on the rolled product
edge/strip edge that is at the borders of the flat rolled product
often leads to step-like patterns in the roller surface. It is
therefore often necessary for measures to be taken in order to
avoid such steps being imprinted into the flat rolled product.
[0010] The prior art discloses various procedures to avoid such
steps being imprinted into the flat rolled product.
[0011] In the simplest case, the production is adapted. In, the
course of a roller work cycle, firstly a few rolled products are
rolled which become gradually wider. The rolling of these rolled
products heats up the roller. Subsequently, only ever rolled
products are rolled having a width that decreases gradually. This
procedure is known in technical circles as the so-called coffin lid
method. It has the advantage that the flat rolled products can be
rolled between the worn edges of their predecessors.
[0012] A further approach consists in mechanically grinding away
the worn edges during the rolling process. Such a method is known
for example from WO 2006/059 667 A1.
[0013] A further approach consists in spreading the worn edge by
virtue of the corresponding rollers being axially displaced during
the rolling process, in particular between the rolling of rolled
products which are rolled in succession. This procedure is
generally known for "normal" rollers which have a substantially
cylindrical roller camber. In WO 2006/000 290 A1, however, this
procedure is explained for rollers which are provided with a
contour which is curved in the manner of a bottleneck.
[0014] The procedure known from WO 2006/000 290 A1 already presents
an advancement over a procedure, in which the displacement of the
rollers for rolling a specified flat rolled product is determined,
without taking into consideration the displacement of the rollers
during the rolling of previously rolled flat rolled products.
[0015] However, the procedure known from WO 2006/000 290 A1 is also
capable of improvement. In particular, undesired accumulation of
wear can also occur at those points of the rollers which are
situated in the region of the rolled product edges.
[0016] The object of the present invention consists in providing
possibilities by means of which in particular the wear, as seen in
the direction of the axis of rotation of the rollers, can be
reliably distributed over a sufficiently large region and thus at
the same time an accumulation of the wear at individual points of
the rollers can be reliably counteracted.
[0017] According to the invention, a method of the type stated at
the outset is configured so that, prior to the rolling of the
respective rolled product, the control device determines for a
plurality of axial positions of the rollers how far a predetermined
target rolling gap contour can be approximated by actuating the
adjusting mechanisms while taking into account technological
boundary conditions. The control device classifies as permissible
those axial positions in which a deviation of the resulting rolling
gap contour from the target rolling gap contour lies below a
predetermined limit. The control device removes blocked axial
positions from the set of the axial positions classified as
permissible so that at least one axial position classified as
permissible still remains even after the removal of the blocked
axial positions, and the control device determines one of the
remaining axial positions as the resulting axial position.
[0018] The rolling stand may be a two-high stand, that is a rolling
stand in which no further rollers apart from the aforementioned
rollers are present. In this case, the rollers according to the
invention are the working rollers of the rolling stand. As a rule,
however, the rolling stand has at least two backup rollers in
addition to the rollers, wherein the rollers are in each case
arranged between the backup rollers and the rolled product. In this
case, the rolling stand is usually a four-high stand or a six-high
stand. A four-high rolling stand that has a total of four rollers
arranged above one another. In this case, only backup rollers are
present in addition to the rollers according to the invention.
[0019] Alternatively, the rolling stand may be a six-high stand,
that is a rolling stand which, in addition to the backup rollers
and the working rollers, has two intermediate rollers which are in
each case arranged between one of the support rollers and one of
the working rollers. In this case, the rollers according to the
invention can likewise be the working rollers of the rolling stand.
Alternatively, they can be the intermediate rollers. It is even
possible in the case of a six-high stand that both the working
rollers and the intermediate rollers are axially displaceable, so
that both the working rollers and the intermediate rollers are
rollers in the sense of the present invention.
[0020] It is possible that the rollers are provided with a
cylindrical contour. However, full advantages are provided by the
present invention when the rollers are provided with a contour
which is curved in the axial direction in the manner of a
bottleneck.
[0021] Within the scope of determining the permissible axial
positions, the control device particularly takes into consideration
technological boundary conditions of the rolling stand. Such
boundary conditions are determined for example by the adjusting
limits of the adjusting mechanisms and by the maximum possible
adjusting speeds of the adjusting mechanisms. The adjusting limits
of the adjusting mechanisms and the maximum possible adjusting
speed can be technically conditioned or can be limited by
corresponding stipulations of an operator.
[0022] The rolling gap contour corresponds to the thickness of the
flat rolled product after rolling, positionally resolved over the
strip width. The thickness of the flat rolled product is here
determined over the strip width at at least 5 points, preferably at
at least 10 points, and for example at 20 points or more.
[0023] The manner and way in which the control device then
determines the actually used axial position from the remaining
axial positions can be according to requirement.
[0024] For example, it is possible that the control device
determines the resulting axial position on a stochastic basis. This
very procedure particularly avoids a situation in which, for
whatever reasons, specific axial positions are used
disproportionately often and thus wear results in particular at
those points of the further rollers at which the resulting rolled
product edges are situated during the rolling of the flat rolled
product.
[0025] Alternatively, it is possible that the control device
assigns an evaluation to at least the remaining axial positions on
the basis of an evaluation criterion and that the control device
determines the resulting axial position on the basis of the
evaluation. As a result, the optimal axial position, which
corresponds to the evaluation, can be used in each case for rolling
the respective flat rolled product. The control device can
determine the evaluation in particular on the basis of
technological criteria.
[0026] The blocking of axial positions can also occur according to
requirement.
[0027] For example, it is possible that the control device receives
a blocking command from an operator, and the control device
subsequently blocks axial positions specified in the blocking
command. As a result, the operator is capable of blocking specific
disadvantageous axial positions, for example on the basis of
superordinate technological knowledge which is not present in the
control device.
[0028] As already mentioned, the rolling of flat rolled products
gives rise to worn edges in the rollers. The position of these worn
edges is generally known to the control device because the control
device generally knows which flat rolled product has already been
rolled (with which width) at which axial position of the further
rollers, that is where the worn edges have arisen. In addition, it
is possible according to requirement to also take into
consideration the camber and the thermal crown of a respective
roller. As a result, it is therefore possible that, while taking
into consideration a camber, a thermal crown and/or a wear of the
rollers, the control device determines a resulting edge of one of
the rollers and blocks those axial positions at which the resulting
edge of one of the rollers would be positioned on a rolled product
edge of the flat rolled product.
[0029] Furthermore, the control device preferably blocks those
axial positions which are situated in a predetermined region around
that axial position in which the flat rolled product that was
rolled immediately beforehand is rolled. This ensures that, during
the rolling of a plurality of flat rolled products, the further
rollers are positioned in a relatively large displacement region.
This causes the result that the wear of the further rollers is
distributed over a large region of the width of the further
rollers. As a result, the service life of the further rollers is
increased. In the simplest case, the predetermined region is
symmetrical with respect to the axial position in which the flat
rolled product that was rolled immediately beforehand is rolled. In
this case, the axial position in which the flat rolled product that
was rolled immediately beforehand is rolled is situated in the
center of the predetermined region. However, the region can also be
arranged asymmetrically.
[0030] It is possible that the control device blocks those axial
positions which are situated in the predetermined region only for
the flat rolled product to be rolled next in each case.
Alternatively, the control device can block the corresponding axial
positions for a plurality of rolled products which are rolled
subsequently. Furthermore, although the control device blocks the
corresponding axial positions for a number of flat rolled products,
it is subsequently the case that, if the corresponding number of
flat rolled products has thus been rolled, the control device
cancels the block again. This applies irrespective of whether the
number of flat rolled products for which the block has occurred is
1 or greater than 1.
[0031] As already mentioned, the blocking of axial positions
actually classified as permissible is only performed when at least
one axial position classified as permissible still remains after
the blocking. As a rule, the control device blocks at least the
current axial position in which the flat rolled product that was
rolled immediately beforehand is rolled. However, other criteria
are also possible, for example, the blocking of axial positions by
the operator takes priority. The prioritization can be rigidly
predetermined or be stipulated by the operator.
[0032] The object is furthermore achieved by a non-transitory
control program. The processing of the control program has the
effect that the control device carries out a method according to
the invention.
[0033] The object is furthermore achieved by a control device. The
control device is designed such that it carries out a method
according to the invention. In particular, the control device can
be programmed with a control program according to the
invention.
[0034] The object is furthermore achieved by a rolling stand for
rolling a flat rolled product, and the rolling stand is controlled
by a control device according to the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] The properties, features and advantages of this invention
which are described above and the manner and way in which they are
achieved will become better and more clearly understandable in
connection with the following description of the exemplary
embodiments, which are explained in more detail in conjunction with
the drawings. Here, in schematically illustrated form:
[0036] FIG. 1 shows a rolling stand from the side,
[0037] FIG. 2 shows the rolling frame from FIG. 1 from the
front,
[0038] FIG. 3 shows a further rolling stand from the side,
[0039] FIG. 4 shows the rolling frame from FIG. 3 from the
front,
[0040] FIG. 5 shows a pair of rollers,
[0041] FIG. 6 shows a flow diagram,
[0042] FIG. 7 shows a profile of a quality value as a function of
the axial position, and
[0043] FIG. 8 shows a pair of working rollers and a flat rolled
product.
DESCRIPTION OF THE EMBODIMENTS
[0044] According to FIGS. 1 to 4, a flat rolled product 2 is
intended to be rolled in a rolling stand 1. The rolling stand 1 has
at least one pair of rollers 4, 5, between which the flat rolled
product 2 passes. In principle, it is possible that only the
rollers 4, 5 are present and that the rolling stand 1 is thus
designed as a two-high stand. As a rule, however, a pair of backup
rollers 3 is additionally present. In this case, the rollers 4, 5
are arranged between the backup rollers 3 and the flat rolled
product 2. In particular, in FIGS. 1 to 4, at least working rollers
4 are present as a rule, that is rollers which in operation are in
direct contact with the flat rolled product 2. If, as illustrated
in FIGS. 1 and 2, only the working rollers 4 are present apart form
the backup rollers 3, the rolling stand 1 is a four-high stand. If,
as illustrated in FIGS. 3 and 4, intermediate rollers 5 are also
present in addition to the backup rollers 3 and the working rollers
4, the rolling stand 1 is a six-high stand.
[0045] The present invention will be explained below in conjunction
with embodiments in which the working rollers 4 are axially
displaceable in opposite directions both for a four-high stand and
for a six-high stand. However, in a six-high stand, whether
alternatively to or additionally to the working rollers 4, it is
also possible that the intermediate rollers 5 are axially
displaceable.
[0046] Furthermore, in the invention, a distinction is made between
various rolled products 2. It is possible that the various rolled
products 2 are physically separated from one another, causing
necessarily a longer or shorter rolling pause between the rolling
of a rolled product 2 and of the following rolled product 2.
However, it is also possible that the subdivision into various
rolled products 2 is of a purely imaginary kind, so that a longer
rolled product 2 is only conceptually subdivided into various
shorter rolled products 2.
[0047] According to FIGS. 2 and 4, as already mentioned, at least
one or both of the working rollers 4 are axially displaceable in
opposite directions. The corresponding displacement state is
referred to below as axial position x. In the context of the
present invention, "axial position" is thus used not in the sense
of a specific point along a roller barrel of a roller 3, 4, 5 or
over the width of the flat rolled product 2, but in the sense of a
specific sliding position of one working roller 4 in relation to
the other working roller 4.
[0048] The working rollers 4 can be provided according to
requirement with a specific contour. For example, they can be
provided with a cylindrical contour. According to the illustration
in FIG. 5, the working rollers 4 are each provided over their
barrel length with a contour which is curved in the manner of a
bottleneck. Such bottleneck-like contours are known in technical
circles for example as CVC camber and as SmartCrown camber. In the
loading-free state of the rolling stand 1, the contours of the
working rollers 4 as a rule supplement one another in complementary
fashion in a (1) axial position x. However, embodiments are also
possible in which the supplementation is not complementary and/or
occurs only in the loaded state of the rolling stand 1.
Furthermore, the curved contours can have bevels or gradual
transitions at their axial ends. However, independently of the
concrete embodiment of the contours of the working rollers 4, the
working rollers 4 form a parabolic rolling gap, wherein, in the
case of the bottleneck-like contours, the extent of the
parabolicity depends on the extent of the axial displacement of the
working rollers 4.
[0049] According to FIGS. 1 to 4, the rolling stand 1 further has a
bending system 6. A bending system for the rollers does not bend
the rolled metal strip but the work rolls themselves in a direction
perpendicular to their roll axes. It is a device which can act
independent of the shifting system that shifts the rolls along
their axial direction and is explained in U.S. Pat. No. 7,895,871
B2, for instance, pressure cylinders act on the chocks of the work
rolls in a vertical direction. Hence, a bending system constitutes
a means for modifying and controlling the resulting roll gap
profile in a direction perpendicular to the transport direction of
the metal strip, with the largest impact at the lateral edge
portions of a metal strip. The resulting effect of the bending
system must be known to the control device of the roll stand in
advance such that the control device can properly actuate the
bending system during the rolling process.
[0050] By means of the bending system 6, the working rollers 4 may
be bent in a defined manner in a manner known per se. The bending
system 6 also particularly allows the rolling gap to have a
parabolic shape imparted thereto. It is therefore possible within
certain limits for the effect of the axial displacement of the
working rollers 4 on the one hand at the effect of the bending
system 6 on the other hand to be mutually reinforcing or mutually
compensating depending on the manner and extent of the respective
actuation of a sliding system 7, by means of which the working
rollers 4 can be displaced, and of the bending system 6. The two
systems 6, 7 thus make it possible in particular for the rolling
gap contour to be set.
[0051] The rolling stand 1 is controlled by a control device 8. In
particular, the bending system 6 and the sliding system 7 are
controlled by the control device 8. In operation, the control
device 8 carries out a method which will be explained in more
detail below. In particular, the control device 8 can be programmed
with a non-transitory control program 9 for this purpose. In this
case, the control program comprises a machine code 10 which can be
processed by the control device 8. The processing of the machine
code 10 causes the control device 8 to carry out the corresponding
method, which in particular comprises controlling the bending
system 6 and the sliding system 7.
[0052] According to FIG. 6, in a step S1, the control device 8
determines for a plurality of axial positions x of the working
rollers 4 which are defined by a respective actuation of the
sliding system 7 and by which respective actuation of the bending
system 6 the rolling gap contour optimally approximates a
predetermined target rolling gap contour. It also simultaneously
determines a quality value A for the correspondence of the
resulting rolling gap contour with the target rolling gap contour.
The corresponding situation is illustrated in FIG. 7 by a
corresponding quality value A as a function over the axial
positions x. The control device 8 can determine the quality value A
for example by means of a cost function. In this case, particularly
at a number of supporting points over the width of the flat rolled
product 2, the respective local deviation of the rolling gap
contour from the target rolling gap contour is included in the cost
function. The number of supporting points over the width of the
flat rolled product 2 at which the control device 8 respectively
determines the respective local deviation of the rolling gap
contour from the target rolling gap contour is as a rule at least 5
points, and preferably at least 10 points. In many cases, the
comparison is carried out even on a still considerably larger
number, for example at 20, 50 or even more supporting points.
[0053] It is additionally possible for the cost function to include
further variables, for example an extent and/or a speed with which
the axial position x has to be adjusted, starting from a current
axial positioning that is the positioning of the corresponding
adjusting system 6, 7 at the time of the rolling of the flat rolled
product 2 that was rolled immediately beforehand (referred to below
as rolled product 2A).
[0054] The control device 8 can determine the axial positions x
discretely--for example every 5 mm, every 10 mm or every 20 mm
within the possible displacement range of the working rollers 4 or
continuously. In the last-mentioned case, determination of the
quality value A occurs as a rule only for supporting points of the
axial position x. The control device 8 interpolates the quality
value A between the supporting points.
[0055] The control device 8 carries out step S1 prior to the
rolling of the respective flat rolled product 2 (referred to below
as rolled product 2B). As a rule, the control device 8 carries out
step S1 furthermore after the rolling of the rolled product 2A that
was rolled immediately beforehand.
[0056] The control device 8 takes account of technological boundary
conditions within the context of carrying out step S1. Such
boundary conditions can consist in particular of the extent to
which the bending system 6 and/or the sliding system 7 can be
actuated at all, that is the maximum possible sliding stroke and
the maximum possible bending stroke. Alternatively and in
particular additionally, the boundary conditions can consist in the
fact that, with consideration of a maximum adjusting speed for the
sliding system 7, the possible range of axial positions x is
limited and/or, with consideration of a maximum adjusting speed for
the bending system 6, a limitation of the achievable rolling gap
contour is carried out.
[0057] In a step S2, the control device 8 determines those axial
positions x at which the quality value A (based substantially on
the deviation of the resulting rolling gap contour from the target
rolling gap contour) lies below a predetermined limit MAX. These
axial positions x represent the total set of the permissible axial
positions x.
[0058] In a step S3, the control device 10 then removes blocked
axial positions x from the set of the permissible axial positions
x.
[0059] It is possible for example for the control device 8 to
receive a blocking command C from an operator 11 within step S3
(see FIGS. 1 and 3). In this case, the control device 8 blocks the
axial positions x specified in the blocking command C. For example,
on account of the stipulation of the operator 11, the control
device 8 can block the axial position x which is supplemented by
the letter A in FIG. 7.
[0060] Alternatively or additionally, it is possible that,
according to the illustration in FIG. 8, the control device 8
determines at least one resulting edge 12 of the working rollers 4
and checks at which axial position x of one of the working rollers
4 the resulting edge 12 would be positioned on a rolled product
edge 13 of the rolled product 2B to be rolled. In this case,
according to the illustration in FIG. 7, the control device 8 for
example blocks the axial position x supplemented by the letter B in
FIG. 7. It is possible that, in the context of determining the
resulting edge 12, the control device 8 considers only the wear of
the working rollers 4. However, the control device 8 preferably
determines the resulting edge 12 with consideration of the camber,
the thermal crown and/or the wear of the working rollers 4.
[0061] Alternatively or additionally, it is possible that,
according to the illustration in FIG. 7, the control device 8
blocks those axial positions x which are situated in a
predetermined region around that axial position x at which the flat
rolled product 2A that was rolled immediately beforehand, that is
the flat rolled product 2A here, is rolled. For example, the
control device 8 can block that axial position x whose spacing a
lies below a minimum spacing amin from that axial position x at
which the flat rolled product 2 that was rolled immediately
beforehand is rolled. In FIG. 7, these are the axial positions x
supplemented by the letter C.
[0062] In the last-mentioned case, that is the block in dependence
on the predetermined region, it is possible that the block applies
only to the flat rolled product 2 to be rolled next, that is the
flat rolled product 2B. Alternatively, it is possible to maintain
the block for a predetermined number of flat rolled products 2, for
example for the flat rolled product 2B and the next two flat rolled
products 2. Subsequently, however, the control device 8
automatically cancels the block again. Furthermore, the duration of
the block can be a function of sign and/or magnitude of the spacing
a, in particular can decrease with increasing spacing a.
[0063] The extent to which, in step S3, the control device 8 blocks
axial positions x can be determined according to requirement.
[0064] However, irrespective of the extent of the blocks, the
blocking is carried out only to the extent that, even after the
removal of the blocked axial positions x from the set of the axial
positions x classified as permissible, at least one axial position
x still remains, that is both permissible and not blocked.
Expressed in other terms: if only a single axial position x is
permissible, this axial position x must not be blocked in step S3
since otherwise there would no longer be available a permissible
axial position x for the rolling of the flat rolled product 2. If,
by contrast, the number of permissible axial positions x is greater
than 1, at least one (in principle permissible) axial position x is
blocked in step S3. However, the blocking of axial positions x is
carried out only to such a degree that even then at least one axial
position x still remains permissible. Furthermore, during blocking,
priority is as a rule given to blocking that axial position x at
which the flat rolled product 2 that was rolled immediately
beforehand that is the flat rolled product 2A here is rolled.
However, other prioritizations are also possible in principle.
[0065] Furthermore, the blocking of axial positions x is not simply
optional but absolutely necessary if the possibility exists at all
for blocking axial positions x. Within step S3, the control device
8 thus always checks whether the number of permissible axial
positions x is greater than 1. If this is the case, at least one
axial position x is blocked. If, on the other hand, this is not the
case, but also only then, there is no blocking of the axial
position x which is permissible alone in this case.
[0066] In a step S4, the control device 8 determines the respective
axial position x at which the flat rolled product 2 now to be
rolled, that is the rolled product 2B according to the example, is
intended to be rolled. This axial position x is referred to below
as the resulting axial position x. The resulting axial position x
is determined by selecting one of the permissible and at the same
time not blocked axial positions x. Step S4 is also carried out
prior to the rolling of the corresponding rolled product 2.
[0067] The manner and way in which the control device 8 determines
the resulting axial position x can occur for example on a
stochastic basis. Alternatively, the control device 8 can determine
an evaluation for the axial positions x on the basis of an
evaluation criterion and assign it to the axial positions x. In
this case, the control device 8 determines the resulting axial
position x on the basis of the evaluation. It is sufficient for the
determination and assignment of the evaluation to be carried out
only for the remaining axial positions x, that is the permissible
and at the same time not blocked axial positions x. This is because
the determination of the resulting axial position x also occurs
only with consideration of these axial positions x.
[0068] The evaluation can be determined according to requirement.
The control device 8 preferably determines the evaluation on the
basis of technological criteria, in particular the quality value
A.
[0069] In a step S5, the control device 8 finally prescribes the
resulting axial position x for the rolling stand 1 as axial
position x for rolling the flat rolled product 2--the rolled
product 2B according to the example. The corresponding rolled
product 2 is thus rolled in the rolling stand 1 with this axial
position x of the working rollers 4 and with the bending system 6
in the state which corresponds thereto and which is determined
within step S1.
[0070] The present invention has been explained above in such a way
that the working rollers 4 are the axially displaceable rollers.
However, in the case of a six-high stand, it is possible that the
intermediate rollers 5 are axially displaceable. In this case, the
method according to the invention is carried out with respect to
the intermediate rollers 5. In the case of a six-high stand, it is
even possible that both the working rollers 4 and the intermediate
rollers 5 are axially displaceable. In this case, the method
according to the invention can be carried out both with regard to
the working rollers 4 and with regard to the intermediate rollers
5.
[0071] The present invention has many advantages. In particular, it
is possible to ensure in a simple and reliable manner that the wear
of the working rollers 4 and/or of the intermediate rollers 5 is
spread over a large region of their axial extent, with the result
that a significant worn edge cannot be formed anywhere. Where
required, it is even possible for the axial position x to be
determined sequentially in succession in such a way that a desired
roller wear is worked towards in a very targeted manner. The
various possibilities of blocking axial positions x and the various
possibilities of determining the resulting axial position x from
the remaining axial positions x results in a high degree of
flexibility, and therefore the procedure according to the invention
can be applied without further modifications in the multiplicity of
rolling stands.
[0072] Although the invention has been more fully illustrated and
described in detail by means of the preferred exemplary embodiment,
the invention is not limited by the disclosed examples and other
variants can be derived therefrom by a person skilled in the art
without departing from the scope of protection of the
invention.
LIST OF REFERENCE SIGNS
[0073] 1 Rolling stand
[0074] 2 Flat rolled products
[0075] 3 Backup rollers
[0076] 4 Working rollers
[0077] 5 Intermediate rollers
[0078] 6 Bending system
[0079] 7 Sliding system
[0080] 8 Control device
[0081] 9 Control program
[0082] 10 Machine code
[0083] 11 Operator
[0084] 12 Resulting edge
[0085] 13 Rolled product edge
[0086] a Spacing
[0087] amin Minimum spacing
[0088] A Quality value
[0089] MAX Limit
[0090] S1 to S5 Steps
[0091] x, xA, xB, xC Axial positions
* * * * *