U.S. patent application number 13/256404 was filed with the patent office on 2012-01-05 for method for providing at least one work roll for rolling rolling stock.
This patent application is currently assigned to SMS SIEMAG AKTIENGESELLSCHAFT. Invention is credited to Ralf Wachsmann.
Application Number | 20120000263 13/256404 |
Document ID | / |
Family ID | 42338053 |
Filed Date | 2012-01-05 |
United States Patent
Application |
20120000263 |
Kind Code |
A1 |
Wachsmann; Ralf |
January 5, 2012 |
METHOD FOR PROVIDING AT LEAST ONE WORK ROLL FOR ROLLING ROLLING
STOCK
Abstract
The invention relates to a method for providing at least one
work roll (1, 2) for rolling strip-shaped rolling stock (3),
wherein the work roll (1, 2) is provided to interact with a second
roll (4, 5), particularly with an intermediate or backup roller and
be supported by said second roll, wherein the second roll (4, 5)
has a background area (6) in the axial end regions thereof. In
order to improve the quality of a rolled strip, the method
according to the invention provides the following steps: a)
calculating the roll nip profile resulting between two interacting
work rolls (1, 2), wherein a defined width of the rolling stock (3)
is assumed, which extends at least partially into the region of the
background area (6) of the second roll (4, 5); b) defining a
desired rolling stock contour that is to be created by the rolling
process when passing the work rolls (1, 2); c) calculating a
compensation cut for the work roll (1, 2) by subtracting the
defined rolling stock contour according to step b) from the roll
nip profile according to step a) and multiplying the calculated
difference with a damping factor (K); d) at least partially
applying the compensation cut calculated according to step c) to at
least one work roll (1, 2).
Inventors: |
Wachsmann; Ralf; (Siegen,
DE) |
Assignee: |
SMS SIEMAG
AKTIENGESELLSCHAFT
Dusseldorf
DE
|
Family ID: |
42338053 |
Appl. No.: |
13/256404 |
Filed: |
April 15, 2010 |
PCT Filed: |
April 15, 2010 |
PCT NO: |
PCT/EP2010/002302 |
371 Date: |
September 13, 2011 |
Current U.S.
Class: |
72/236 |
Current CPC
Class: |
B21B 2263/02 20130101;
B21B 2269/14 20130101; B21B 2263/04 20130101; B21B 2271/02
20130101; B21B 2267/18 20130101; B21B 13/142 20130101; B21B 2267/02
20130101; B21B 2027/022 20130101; B21B 27/021 20130101; B21B
2263/06 20130101 |
Class at
Publication: |
72/236 |
International
Class: |
B21B 27/02 20060101
B21B027/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 17, 2009 |
DE |
10 2009 017 536.9 |
Claims
1-10. (canceled)
11. A method for preparing at least one work roll for rolling of
rolling stock, wherein the work roll is provided to interact with a
second roll, and to be supported by the second roll, and wherein
axial end regions of the second roll have a setback, wherein the
method comprising the steps of: (a) computing a roll gap profile
that is formed between two interacting work rolls, where a defined
width (B) of the rolling stock is assumed, which extends at least
partially into a region of the setback of the second roll; (b)
defining a desired rolling stock contour that is to be produced by
the rolling process during passage through the work rolls; (c)
computing a compensation cut for the work roll by subtracting the
rolling stock contour defined according to step (b) from the roll
gap profile according to step (a) and multiplying the computed
difference by a damping factor (K); and (d) at least proportionally
applying compensation cut computed according to step (c) to at
least one work roll.
12. The method in accordance with claim 11, including superimposing
the compensation cut according to step (c) on another profiling of
the work roll.
13. The method in accordance with claim 12, wherein the another
profiling of the work roll is a parabolic profiling or an S-shaped
profiling.
14. The method in accordance with claim 11, wherein the damping
factor (K) for the computation according to step (c) is
0.3-0.9.
15. The method in accordance with claim 14, wherein the damping
factor (K) for the computation according to step (c) is
0.4-0.8.
16. The method in accordance with claim 11, including basing the
computation according to step (a) on the maximum width (B) provided
for the rolling stock that is to be rolled with the work rolls.
17. The method in accordance with claim 11, including basing the
computation according to step (a) on a well-defined rolling
force.
18. The method in accordance with claim 11, including basing the
computation according to step (a) on a well-defined work roll
bending force (F.sub.B).
19. The method in accordance with claim 11, including basing the
definition according to step (b) on the same parameters as in step
(a).
20. The method in accordance with claim 11, including basing the
definition according to step (b) on a roll gap profile computed
offline.
21. The method in accordance with claim 20, including basing the
roll gap profile computed offline on an extended backup roll
barrel, so that edges of the rolling stock are not located in the
region of the setback of the second rolls.
Description
[0001] The invention concerns a method for preparing at least one
work roll for the rolling of preferably strip-shaped rolling stock,
wherein the work roll is provided to interact with a second roll,
especially an intermediate roll or backup roll, and to be supported
by this roll, and wherein the axial end regions of the second roll
have a setback.
[0002] In particular, when very wide plate is being rolled (e.g.,
width greater than 3,000 mm), undesired profile shapes sometimes
develop in the strip, especially W-shaped profiles and ridge
formation near the edges and flatness defects (quarter waves) in
the final product.
[0003] This can be attributed, among other things, to the fact that
during the rolling of wide strips or plates it happens that the
outer regions of the rolling stock are located in the area of the
setback of the backup rolls or intermediate rolls or, in the case
of extended work rolls, actually lie outside the edges of the
barrels of the backup rolls or intermediate rolls. The work roll
bends back in these regions, and as a result of this, a
nonparabolic profile shape can develop in the roll gap, namely,
e.g., the aforementioned ridge formation. High rolling forces and
work roll bending forces can intensify this effect.
[0004] The rolling stock profile is the distribution of the
thickness of the rolling stock over its width. Rolling stock
profiles that deviates greatly from the parabolic form are
generally undesirable, since they can lead to nonflatness in the
rolling process or in the downstream processes. In addition, the
accuracy to gage of the product can be adversely affected.
[0005] The application of roll cuts to work rolls for
systematically affecting the roll gap profile is already known. For
example, EP 0 294 544 B1 provides that the work roll is provided
with a profile that is described by a polynomial. EP 1 307 302 B1
proposes a similar solution, in which a so-called CVC profile is
provided. Other similar and different solutions are disclosed in EP
1 703 999 B1, EP 0 937 515 B1, JP 3032412 A, JP 9253726 A, DE 39 19
285 A1, JP 8332509 A, JP 6015322 A, and JP 2179308A. The profiles
applied on the work roll are thus parabolic contours or contours
described by polynomials. In the latter case, when an axial work
roll shifter is present and shifting is used a profile correcting
element, the S-shaped contours described by the aforesaid
polynomials are applied to the roll (CVC cut).
[0006] The application of special contours to reduce edge drop or
to reduce ridge formation is also well known. The goal here is to
influence the rolling stock profile contour in the immediate edge
region in order to compensate effects of work roll flattening in
the roll gap or of thermal expansion of the work roll on the roll
gap profile.
[0007] The prior art cited above does not provide practical advice
on how good rolling results can be achieved despite furnishing
backup rolls or intermediate rolls with a setback. But this is
precisely why the aforementioned problems occur, especially in the
case of very wide strips.
[0008] Therefore, the objective of the invention is to propose a
method for preparing a work roll of the type described at the
beginning, with which it is possible, even when there is a
corresponding setback of the backup roll or intermediate roll, to
achieve optimum rolling, i.e., to roll a strip that is
characterized by high quality and the desired shape. Accordingly,
undesirable nonparabolic effects of the backup roll or intermediate
roll setback on the roll gap profile shape are to be largely
compensated. The provision of the work rolls with a special cut
(e.g., CVC cut) should not be compromised.
[0009] The solution to this problem by the invention is
characterized in that the method for preparing at least one work
roll for the rolling of preferably strip-shaped rolling stock has
the following steps:
[0010] (a) computation of the roll gap profile that is formed
between two interacting work rolls, where a defined width of the
rolling stock is assumed, which extends at least partially into the
region of the setback of the second roll;
[0011] (b) definition of a desired rolling stock contour that is to
be produced by the rolling process during passage through the work
rolls;
[0012] (c) computation of a compensation cut for the work roll by
subtraction of the rolling stock contour defined according to step
(b) from the roll gap profile according to step (a) and
multiplication of the computed difference by a damping factor;
[0013] (d) at least proportional application of the compensation
cut computed according to step (c) to at least one work roll.
[0014] The compensation cut according to step (c) can be
superimposed on another profiling of the work roll. This other
profiling of the work roll is preferably a parabolic profiling or
an S-shaped profiling (so-called CVC profiling).
[0015] The damping factor for the computation according to step (c)
is preferably 0.3-0.9 and more preferably 0.4-0.8. A value of 0.6
has been found to be especially effective. The factor is chosen in
such a way that for the broad strips or products, ridge-shaped
profile forms no longer arise or the ridges are greatly reduced,
and for narrower dimensions of the strip, no disturbing effects or
only slightly disturbing effects arise.
[0016] In accordance with a preferred embodiment, the computation
according to step (a) is based on the maximum width provided for
the rolling stock that is to be rolled with the work rolls.
[0017] The computation according to step (a) is preferably based on
a well-defined rolling force and a well-defined work roll bending
force. The definition according to step (b) is preferably based on
the same parameters as in step (a).
[0018] It is advantageous for the profile that is to be defined in
accordance with step (b) to be based on a roll gap profile computed
offline. In this case, it can be provided that the roll gap profile
computed offline is based on an extended backup roll barrel, so
that the edges of the rolling stock are not located in the region
of the setback of the second rolls.
[0019] Accordingly, the proposed method provides a work roll cut to
compensate the bending behavior of the work roll in the region of
the backup roll setback. A possibly desired special roll cut (e.g.,
a CVC cut) is superimposed on the compensation cut provided in
accordance with the invention.
[0020] An essential feature of the proposed cut is that the effect
of the setback compensation is almost independent of the axial
shift position of the work rolls to each other, so that in the case
of shiftability of the work rolls, this effect is effective over
the entire shift range.
[0021] The compensation cut can be used both on work rolls that can
be axially shifted and on work rolls that cannot be shifted.
[0022] It can be proportionally applied to only one work roll or to
the upper and the lower work roll.
[0023] The compensation cut can be combined with any desired roll
cut, i.e., it can be superimposed on it. The height of the cut can
be varied according to the current work roll diameter. The height
can also be adapted to the current backup roll contour or
intermediate roll contour (with respect to wear).
[0024] The cut can be described, for example, by a sequence of
points or by a mathematical function (e.g., by a polynomial
function).
[0025] The drawings illustrate a specific embodiment of the
invention.
[0026] FIG. 1 is a schematic drawing of the work rolls and backup
rolls of a four-high rolling stand during the rolling of
strip-shaped rolling stock, viewed in the direction of rolling.
[0027] FIG. 2 shows the variation of the roll gap, i.e., the height
of the roll gap over the width less the height in the center,
between two work rolls over the width of the rolling stock during
the rolling of the rolling stock without the use of the method of
the invention.
[0028] FIG. 3 shows the variation of the roll gap between two work
rolls over the width of the rolling stock as a target contour
(ideal profile shape).
[0029] FIG. 4 shows the variation of the roll gap between the work
rolls over the width of the rolling stock as the difference contour
between the target contour according to FIG. 3 and the variation
according to FIG. 2.
[0030] FIG. 5 shows the variation of a compensation cut for the
work rolls over the width of the rolling stock.
[0031] FIG. 6 shows the effect of the compensation cut
(supplementary cut) over the width of the rolling stock for
different axial shift positions on the unloaded roll gap.
[0032] FIG. 7 shows the variation of the roll gap between two work
rolls over the width of the rolling stock with the use of the
compensation cut according to FIG. 5.
[0033] FIG. 1 shows two work rolls 1, 2, which are part of a
four-high rolling stand (which itself is not shown). The work rolls
1, 2 are supported in a well-known way by backup rolls 4, 5. The
rolling stock 3 that is to be rolled, which in the present case is
a strip with a width B of 3,100 mm, is located between the work
rolls 1, 2.
[0034] In their lateral regions, i.e., their axial end regions, the
backup rolls 4, 5 have a setback 6, i.e., the profile is set back
compared to a pure cylinder. In FIG. 1 this is shown with strong
exaggeration.
[0035] Accordingly, for the embodiment illustrated here, this has
the following consequence: Full support of the work rolls 1, 2 by
the backup rolls 4, 5 is provided only in the middle region over a
distance of 2,050 mm, since each setback 6 in the two lateral
regions extends over a distance of 500 mm. The work rolls, which
have a length of 3,450 mm, extend beyond the width B of the rolling
stock 3 of 3,100 mm.
[0036] The work rolls 1, 2 are acted upon not only by the support
forces of the backup rolls 4, 5 but also by work roll bending
forces F.sub.B and the rolling forces themselves, so that the work
rolls experience reverse bending, which is indicated by the arrows
7.
[0037] The reverse bending of the work rolls in the area of the
setback 6 of the backup rolls thus depends on the rolled width of
the rolling stock 3, the rolling force that is applied, and the
work roll bending force F.sub.B that is set. Therefore, the choice
of a frequently rolled large width of the rolling stock and of a
mean rolling force that is customary for the last passes of a pass
program and a bending force (balancing force) at a low level are
advantageous for the cut configuration. In this regard, we can
initially proceed from average roll diameters. The roll cambers are
chosen in each case in such a way that the computed roll gap
profiles fall within the usual range (about 0.000 mm to 0.200
mm).
[0038] In a first stop of the work roll configuration or
preparation, the roll gap profile to be expected is computed for
the rolling stand to be considered under the aforesaid boundary
conditions for the maximum width to be rolled. An example of the
result of such a computation is shown in FIG. 2. Here we see the
shape of the roll gap profile for a rolling stock width of 3,100 mm
without compensation of the reverse bending effect. It is clearly
seen that the profile takes an undesired course in the lateral
region of the strip due to the reverse bending of the work
rolls.
[0039] After this profile has been determined, an ideal rolling
stock contour is defined for the same case. This can be, for
example, a roll gap profile computed offline under the assumption
of an extended backup roll barrel, so that the edges of the rolling
stock are not located in the area of the setback 6 of the backup
rolls. This ideal profile shape is shown in FIG. 3 as an example of
a target contour, again for a strip with a width of 3,100 mm.
[0040] In the next step, the undesired profile component produced
by the reverse bending effect is determined by subtracting the
target contour (according to FIG. 3) from the roll gap shape
without compensation cut (according to FIG. 2). This is illustrated
in FIG. 4. Sketched here is thus the difference contour between the
target contour and the roll gap shape without compensation, again
for a strip with a width of 3,100 mm. The solid curve is the roll
gap shape without compensation cut, while the dot-dash curve
indicates the target contour. Accordingly, the broken curve
represents the difference contour that is needed to compensate the
reverse bending effect.
[0041] The compensation cut for the work roll is obtained by the
difference contour according to FIG. 4, where the difference that
is determined is multiplied by a damping factor K of, e.g., 0.7.
This factor is chosen in such a way that in the case of broad
strips, ridge-shaped profile forms do not arise, while in the case
of narrower dimensions of the strip, no disturbing effects or only
slightly disturbing effects arise.
[0042] The compensation cut for application to both work rolls 1, 2
is shown in FIG. 5. The graph shows the radius deviation (.DELTA.r)
over the barrel length.
[0043] If the compensation cut is to be applied to only one work
roll, its height is doubled accordingly.
[0044] In the region near the rolling stock towards the edges of
the barrel, the contour should run out harmonically, as is
indicated in FIG. 5 with reference number 8.
[0045] The effect of the supplementary cut on the unloaded roll gap
is illustrated in FIG. 6 for different axial shift positions. The
solid line indicates the curve that is obtained with work rolls 1,
2 that have not been axially shifted. On the other hand, the broken
line shows the curve that is obtained when the upper and lower work
rolls are shifted relative to each other by 150 mm. FIG. 6 thus
shows the effect on the unloaded roll gap as a function of the
axial shift position. It is apparent that even in the case of a
relatively large axial shift of the rolls, the desired effect
remains largely constant.
[0046] Finally, FIG. 7 shows the resultant roll gap shape obtained
with the use of the compensation cut. The improvement that is
realized in the profile shape is apparent from a comparison of this
contour with the original contour without compensation cut
according to FIG. 2.
[0047] When a six-high rolling stand is used instead of the
four-high rolling stand illustrated here, similar results are
obtained, but in this case the backup roll is replaced by the
intermediate roll.
LIST OF REFERENCE NUMBERS AND LETTERS
[0048] 1 work roll [0049] 2 work roll [0050] 3 rolling stock [0051]
4 second roll (intermediate roll, backup roll) [0052] 5 second roll
(intermediate roll, backup roll) [0053] 6 setback [0054] 7 bending
direction (reverse bending of work roll) [0055] 8 harmonic runout
[0056] B width of the rolling stock [0057] K damping factor [0058]
F.sub.B work roll bending force
* * * * *