U.S. patent application number 11/664141 was filed with the patent office on 2008-02-28 for device for the continuous lengthening of a metal strip by traction, and method for operating one such device.
Invention is credited to Holger Behrens, Andreas Gramer, Hans-Georg Hartung, Jan Christoph Hausler, Fritz Luckmann.
Application Number | 20080047314 11/664141 |
Document ID | / |
Family ID | 35355732 |
Filed Date | 2008-02-28 |
United States Patent
Application |
20080047314 |
Kind Code |
A1 |
Gramer; Andreas ; et
al. |
February 28, 2008 |
Device for the Continuous Lengthening of a Metal Strip by Traction,
and Method for Operating One Such Device
Abstract
The invention relates to a device (1) for the continuous
lengthening of a metal strip (2) by traction, said device
comprising, in the strip transporting direction (R), at least three
S-roll units (3, 4, 5, 6, 7) each provided with at least two rolls
(8, 9 10, 11, 12, 13, 14, 15, 16, 17). According to the invention,
the rolls (8, 9, 10, 11, 12, 13, 14, 15, 16, 17) are positioned in
such a way that the metal strip (2) is wound round them at a roll
periphery angle (a) of more than 180.degree., and at least the
second S-roll unit (4) in the strip transporting direction (R)
comprises two rolls (10, 11) with different-sized diameters
(D.sub.10, D.sub.11).
Inventors: |
Gramer; Andreas; (Solingen,
DE) ; Hartung; Hans-Georg; (Pulheim, DE) ;
Behrens; Holger; (Erkrath, DE) ; Hausler; Jan
Christoph; (Duisburg, DE) ; Luckmann; Fritz;
(Grevenbroich, DE) |
Correspondence
Address: |
FRIEDRICH KUEFFNER
317 MADISON AVENUE, SUITE 910
NEW YORK
NY
10017
US
|
Family ID: |
35355732 |
Appl. No.: |
11/664141 |
Filed: |
September 19, 2005 |
PCT Filed: |
September 19, 2005 |
PCT NO: |
PCT/EP05/10078 |
371 Date: |
May 7, 2007 |
Current U.S.
Class: |
72/160 ;
72/116 |
Current CPC
Class: |
B21D 1/05 20130101 |
Class at
Publication: |
072/160 ;
072/116 |
International
Class: |
B21D 1/05 20060101
B21D001/05 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 6, 2004 |
DE |
10 2004 048 658.1 |
Claims
1. A device (1) for the continuous stretcher leveling of metal
strip (2), which device (1) has at least three bridles (3, 4, 5, 6,
7) in the direction of strip transport (R), with each bridle (3, 4,
5, 6, 7) having at least two rolls (8, 9; 10, 11; 12, 13; 14, 15;
16, 17), where the rolls (8, 9, 10, 11, 12, 13, 14, 15, 16, 17) are
positioned in such a way that the metal strip (2) wraps around them
over a contact roll wrap angle (.alpha.) of more than 180.degree.,
wherein at least the second bridle (4) in the direction of strip
transport (R) has two rolls (10, 11) with different diameters
(D.sub.10, D.sub.11).
2. A device in accordance with claim 1, wherein the second roll
(11) of the second bridle (4), which is downstream of the first
roll (10) of the second bridle (4) in the direction of strip
transport (R), is the roll with the larger diameter (D.sub.11).
3. A device in accordance with claim 1 or claim 2, wherein it has
five bridles (3, 4, 5, 6, 7) with at least two rolls each (8, 9;
10, 11; 12, 13; 14, 15; 16, 17).
4. A device in accordance with claim 3, wherein the fourth bridle
(6) in the direction of strip transport (R) has two rolls (14, 15)
with different diameters (D.sub.14, D.sub.15).
5. A device in accordance with claim 4, wherein the downstream roll
(15) of the fourth bridle (6) in the direction of strip transport
(R) has the smaller diameter (D.sub.15).
6. A device in accordance with any of claims 1 to 5, wherein the
diameter of the large-diameter roll (11, 14) of the bridle (4, 6)
is at least 1.25 times larger than the diameter of the
small-diameter roll (10, 15).
7. A device in accordance with claim 6, wherein the diameter of the
large-diameter roll (11, 14) of the bridle (4, 6) is at least 1.5
times larger than the diameter of the small-diameter roll (10, 15)
and preferably twice as large.
8. A device in accordance with any of claims 3 to 7, wherein the
third bridle (5) has two rolls (12, 13) with diameters (D.sub.12,
D.sub.13) that are the same as the diameters (D.sub.11, D.sub.14)
of the larger rolls (11, 14) of the second and fourth bridles (4,
6).
9. A device in accordance with any of claims 3 to 8, wherein the
first and fifth bridles (3, 7) each have two rolls (8, 9; 16, 17)
with diameters (D.sub.8, D.sub.9; D.sub.16, D.sub.17) that are the
same as the diameters (D.sub.10, D.sub.15) of the smaller rolls
(10, 15) of the second and fourth bridles (4, 6).
10. A device in accordance with any of claims 1 to 9, wherein means
(18) for measuring the tensile force present in the metal strip (2)
are installed after the first bridle (3) in the direction of strip
transport (R).
11. A device in accordance with any of claims 1 to 10, wherein the
second bridle (4) in the direction of strip transport (R) is
equipped with means (19) for measuring the tensile force applied to
the metal strip (2) by the rolls (10, 11).
12. A device in accordance with any of claims 3 to 10, wherein the
fourth bridle (6) in the direction of strip transport (R) is
equipped with means (20) for measuring the tensile force applied to
the metal strip (2) by the rolls (14, 15).
13. A device in accordance with any of claims 3 to 12, wherein the
fourth bridle (6) in the direction of strip transport (R) is
equipped with measuring means (21) for measuring the speed of
conveyance (v) of the metal strip (2), which means are connected
with an open-loop or closed-loop control system (22), which
regulates or automatically controls the drives of at least some of
the bridles (3, 4, 5, 6, 7) according to the determined speed of
conveyance (v).
14. A method for operating a device (1) for the continuous
stretcher leveling of metal strip (2), which device (1) has at
least three bridles (3, 4, 5, 6, 7) in the direction of strip
transport (R), with each bridle (3, 4, 5, 6, 7) having at least two
rolls (8, 9; 10, 11; 12, 13; 14, 15; 16, 17), especially a device
in accordance with any of claims 1 to 13, wherein, in the second
bridle (4) in the strip transport direction (R), a tensile stress
which is 96% to 100% of the yield point of the material of the
metal strip (2) is built up in the metal strip (2).
15. A method in accordance with claim 14, wherein, in a device with
five bridles (3, 4, 5, 6, 7), a tensile stress which is greater
than 100% of the yield point of the material of the metal strip (2)
is built up in the metal strip (2) in the third bridle (5) in the
direction of strip transport (R).
16. A method in accordance with claim 15, wherein, in the fourth
bridle (6) in the strip transport direction (R), a tensile stress
which is 96% to 100% of the yield point of the material of the
metal strip (2) is built up in the metal strip (2).
17. A method in accordance with claim 15, wherein, in the fourth
bridle (6) in the strip transport direction (R), a tensile stress
which is greater than 100% of the yield point of the material of
the metal strip (2) is built up in the metal strip (2).
Description
[0001] The invention concerns a device for the continuous stretcher
leveling of metal strip, which device has at least three bridles in
the direction of strip transport, with each bridle having at least
two rolls, which are positioned in such a way that the metal strip
wraps around them over a contact roll wrap angle of more than
180.degree.. The invention also concerns a method for operating a
device of this type.
[0002] EP 0 393 301 B2 discloses a device for the stretcher
leveling of metal strip and a corresponding method for operating
it. The metal strip to be stretched passes through five bridles
arranged in succession, which cause the metal strip to wrap around
the rolls in the shape of an S and can cause tensile stress to
build up in the metal strip by suitable driving of the bridle
rolls. Plastic elongation of the metal strip takes place during the
stretching operation, and this leads to a reduction of the strip
thickness and strip width.
[0003] During this operation, in a first stretcher leveling zone, a
tensile stress is built up which almost reaches the yield point
(.sigma..sub.p 0.2) or even exceeds it. In the event that the strip
tension remains just below the yield point, a prestretching zone,
in which the strip width is elastically reduced, forms around the
roll of the bridle in conjunction with the finite bending radius.
The actual stretching is produced in a second stretcher leveling
zone that is located downstream in the direction of strip
transport. By dividing the stretcher leveling into two zones, the
flatness result in the metal strip after the stretcher leveling is
improved.
[0004] In the solution disclosed in EP 0 393 301 B2, the strip
tension for the elastic deformation of the strip is applied between
a brake roll set and a tension roll set. The strip tension for the
plastic deformation of the strip is produced in a pair of stretcher
leveling rolls arranged between them.
[0005] EP 0 936 954 B1 discloses a stretcher leveling installation
in which the two stretching zones are formed between a brake roll
set and a centrally arranged stretcher roll and between this
stretcher roll and a downstream tension roll set.
[0006] Furthermore, EP 1 245 301 A2 discloses an installation in
which the two stretching zones are formed between the brake roll
set and a driven roll and between this roll and the tension roll
set. It is provided that the length of the first and the second
stretching interval or stretching zone is at least 0.5 times the
maximum strip width, which is intended to improve the flatness
result of the stretching operation.
[0007] Finally, DE 36 36 707 C2 describes a stretcher leveling
installation for metal strip, in which the flatness-improving
effect is achieved by stretching the strip by means of bending in
alternating directions under tension around small rollers.
[0008] Although the previously known devices for the stretcher
leveling of metal strip and the previously known methods already
make it possible to increase the degree of flatness of metal strip,
there is a need to create installations and methods that are
further improved, so that metal strip can be subjected to stretcher
leveling that is even more efficient.
[0009] Therefore, the objective of the invention is to create a
stretcher leveling device of the aforementioned type and a
corresponding stretcher leveling method, with which the stretcher
leveling operation can be further improved.
[0010] In accordance with the invention, the solution to this
problem with respect to a device is characterized by the fact that
at least the second bridle of the stretcher leveling device in the
direction of strip transport has two rolls with different
diameters.
[0011] As will become apparent later, this measure results in an
improvement in the stretcher leveling operation, and this in turn
leads to improved flatness of the processed metal strip.
[0012] It is preferred for the roll with the larger diameter to be
the downstream roll of the second bridle.
[0013] In accordance with a preferred embodiment, the device has
five bridles with at least two rolls each. In this connection, the
fourth bridle in the direction of strip transport can have two
rolls with different diameters. In addition, in this case, the roll
with the smaller diameter can be the downstream roll of the fourth
bridle.
[0014] The diameter of the bridle roll with the larger diameter is
preferably at least 1.25 times larger than the diameter of the
bridle roll with the smaller diameter. The diameter of the bridle
roll with the larger diameter is preferably at least 1.5 times
larger than the diameter of the bridle roll with the smaller
diameter, and especially twice as large.
[0015] In accordance with a further refinement of the invention,
the third bridle has two rolls with diameters that are the same as
the diameters of the larger rolls of the second and fourth bridles.
Furthermore, the first and fifth bridles can each have two rolls
with diameters that are the same as the diameters of the smaller
rolls of the second and fourth bridles.
[0016] Means for measuring the tensile force present in the metal
strip can be installed after the first bridle in the direction of
strip transport. The second bridle in the direction of strip
transport can be equipped with means for measuring the tensile
force applied to the metal strip by the rolls. In addition, the
fourth bridle in the direction of strip transport can be equipped
with means for measuring the tensile force applied to the metal
strip by the rolls.
[0017] An advantageous "speedmaster" operation can be realized if
the fourth bridle in the direction of strip transport is equipped
with measuring means for measuring the speed of conveyance of the
metal strip, which means are connected with an open-loop or
closed-loop control system, which regulates or automatically
controls the drives of at least some of the bridles according to
the determined speed of conveyance.
[0018] The method of the invention for operating the stretcher
leveling device is characterized by the fact that in the second
bridle in the strip transport direction, a tensile stress is built
up in the metal strip which is 96% to 100% of the yield point of
the material of the metal strip. The tensile stress is preferably
96% to 99.8% of the yield point of the material, i.e., just below
100% of the yield point of the material.
[0019] In a device with five bridles, a tensile stress that is
greater than 100% of the yield point of the material of the metal
strip is preferably built up in the metal strip in the third bridle
in the direction of strip transport.
[0020] In addition, it can be provided that, in the fourth bridle
in the strip transport direction, a tensile stress is built up in
the metal strip which is 96% to 100% of the yield point of the
material of the metal strip or again is just below the yield point
(up to 99.8% of the yield point). As an alternative to this, a
tensile stress that is greater than 100% of the yield point of the
material of the metal strip can be built up in the metal strip in
the fourth bridle in the direction of strip transport. Accordingly,
the metal strip is further plastically deformed.
[0021] The sole figure is a highly schematic representation of a
specific embodiment of the invention. It shows a side view of a
device for the stretcher leveling of metal strip, and basically
only the rolls that are used are illustrated in the drawing.
[0022] A metal strip 2, which can be a thin metal strip, is
processed in the stretcher leveling device 1 illustrated in the
drawing. The metal strip can consist of steel, high-grade steel, or
nonferrous metal. Typical strip thicknesses can be 0.05 to 0.5
mm.
[0023] The stretcher leveling device 1 has five bridles 3, 4, 5, 6,
and 7 arranged in succession. Each bridle 3, 4, 5, 6, 7 has two
rolls 8, 9; 10, 11; 12, 13; 14, 15; and 16, 17, respectively. The
rolls are arranged in such a way that the metal strand 2 wraps
around them over a contact roll wrap angle .alpha. of at least
180.degree.. The contact roll wrap angle .alpha. is shown for rolls
8 and 11 by way of example: it is about 210.degree.. The rolls can
be driven, so that strip tension can be applied to the metal strand
2.
[0024] The metal strip 2 passes through the device 1 in strip
transport direction R at a conveyance speed v.
[0025] The strip tension is increased from the surrounding
installation tension level by means of the first bridle 3 on the
entry side. Means 18 for measuring the tensile force in the metal
strip 2 are installed downstream of the bridle 3. The tensile force
downstream of the bridle 3 must be known to be able to define and
then regulate or automatically control the tension level for the
further controlled tension buildup.
[0026] The following bridle 4 has the two rolls 10 and 11, which
have significantly different diameters, namely, diameters D.sub.10
and D.sub.11. The roll diameter D.sub.10 can be about 600 mm
(values between 400 mm and 800 mm are typical), while the diameter
D.sub.11 can be 1,200 mm (values between 1,000 mm and 1,400 mm are
typical). In this connection, the first roll 10 of the bridle 4 has
the same diameter as the rolls 8 and 9 of the first bridle 3.
[0027] The second bridle 4 also has means 19 for measuring the
tensile force in the metal strip 2 (torque measurement). The strip
tension adjusted between the rolls 10 and 11 by suitable activation
of the drives (not shown) of the rolls 10, 11 is at a level such
that theoretically no surface layer plastic deformation of the
strip to be stretched starts to occur yet. The following roll 11 of
the bridle 4 has the significantly larger diameter D.sub.11. This
roll 11 builds up the strip tension to a level between more than
96% of the yield point tension and just less than 100% of the yield
point tension. Since the roll radius is finite, surface layer
stretching due to bending of the strip cannot be excluded. However,
it can be reduced to an acceptable level by the dimensioning of the
diameter.
[0028] Between the roll 11 of the second bridle 4 and the following
roll 12 of the third bridle 5, there is a relatively long
unsupported length of strip, in which a nonuniform stress
distribution over the width of the strip can be equalized by the
increase in tension. In this location, stress peaks due to areas of
unflatness can be equalized by microplastic deformation, but the
actual stretching process does not yet occur here.
[0029] With the roll 12 that comes next in the direction of strip
transport R, the strip tension is then raised to the level
necessary for the desired tensile strain. The diameter D.sub.12 of
this roll 12 is the same as the diameter D.sub.11 of roll 11. Since
the starting level of the strip tension is already very high,
negative effects due to hindered transverse contraction on roll 12
are virtually excluded. For this reason, the stretching interval
between rolls 12 and 13 can also be very short, since equalization
of stress is not necessary.
[0030] With the next bridle 6, it is possible either to lower the
strip tension back to a level between 96% and just below 100% of
the yield point tension and thus to apply no further stretching,
or, alternatively, to impose additional tensile strain on the metal
strip 2 in a systematic way here. Since the unsupported length of
strip is again relatively long between the rolls 13 and 14, the
last nonuniformities in the stress distribution can be removed
here.
[0031] The bridle 6 is again equipped with a roll 14 of large
diameter and a following roll 15 of small diameter and its
configuration is mirror-inverted relative to bridle 4 upstream of
the pair of stretcher leveling rolls 12, 13.
[0032] To allow detection of the strip tension, the bridle 6 is
also provided with means 20 for measuring the tensile force. After
the large-diameter roll 14 of the fourth bridle 6, a strip tension
level is adjusted at which plastic deformation of the metal strip 2
is prevented as it is taken up on the small roll 15 that follows.
The small roll 15 adjusts the strip tension level to the level
required for the following strip tension measurement. The strip
tension measurement is made by means 23 for measuring the tensile
force.
[0033] The configuration of the last, fifth bridle 7 is again
mirror-inverted relative to the first bridle 3. Its rolls 16, 17
have the same small roll diameter as rolls 10 and 15. This bridle 7
reduces the strip tension to the level desired or needed for the
next section of the installation.
[0034] Measuring means 21 for determining the speed of conveyance v
of the metal strip 2 are installed at the fourth bridle 6. The
measuring means 21 transmit the measured value to an open-loop or
closed-loop control system 22, which (as is shown in only a highly
schematic way) acts on the drives of the bridles 3, 4, 5, 6, 7 in
such a way that a desired speed is reached. The roll 14, at which
the speed of conveyance or the strip speed is measured in the
present case, thus acts as the "speedmaster" with a downstream
speed-controlled main drive of the rolls or the tension roll
sets.
[0035] The strip tension is thus maintained at a level between 96%
of the yield point tension and just below 100% of the yield point
tension upstream of the pair of stretcher leveling rolls 12, 13;
the remaining portion of the strip tension necessary to achieve the
set amount of tensile strain is applied in the pair of stretcher
leveling rolls 12, 13. Downstream of the pair of stretcher leveling
rolls 12, 13, the strip tension is either reduced again to between
96% and just below 100% of the yield point tension or increased to
achieve supplementary further tensile strain.
[0036] The last roll 11 of the bridle 4 (brake bridle) before the
pair of stretcher leveling rolls 12, 13 and the first roll 14 of
the following bridle 6 (tension bridle) after the pair of stretcher
leveling rolls 12, 13 have the same diameter as the two rolls 12,
13 of the bridle 5. As explained above, this diameter is
significantly greater than the diameter of the other rolls 8, 9,
10, 15, 16, and 17, all of which have the same diameter.
[0037] The strip tension in the bridle 4 upstream of the bridle 5
(stretcher leveling roll unit) and in the bridle 6 downstream of
the bridle 5 is adjusted by means of strip tension measurement and
torque measurement at the rolls in such a way that theoretically no
surface layer plastic deformation occurs at the smaller of the two
rolls 10 and 15 installed in the bridles 4 and 6, respectively.
[0038] In the illustrated embodiment, the metal strip 2 has a
stress between the two rolls 10 and 11 of about 55-70% of the yield
point of the material. As described above, a tensile stress between
96% of the yield point and just below 100% of the yield point is
present between the rolls 11 and 12. This region is the
prestretching zone. The first principal stretching zone is located
between the rolls 12 and 13. The second principal stretching zone
is the section between rolls 13 and 14, where a tensile stress
between 96% of the yield point and just below 100% of the yield
point is generally present. Between the rolls 14 and 15, a tensile
stress of 55-70% of the yield point of the material is again
present (mirroring the situation between the two rolls 14 and
15).
LIST OF REFERENCE SYMBOLS
[0039] 1 stretcher leveling device [0040] 2 metal strip [0041] 3
bridle [0042] 4 bridle [0043] 5 bridle [0044] 6 bridle [0045] 7
bridle [0046] 8 roll [0047] 9 roll [0048] 10 roll [0049] 11 roll
[0050] 12 roll [0051] 13 roll [0052] 14 roll [0053] 15 roll [0054]
16 roll [0055] 17 roll [0056] 18 means for measuring the tensile
force [0057] 19 means for measuring the tensile force [0058] 20
means for measuring the tensile force [0059] 21 measuring means
[0060] 22 open-loop or closed-loop control system [0061] 23 means
for measuring the tensile force [0062] R strip transport direction
[0063] .alpha. contact roll wrap angle [0064] D.sub.8 diameter of
roll 8 [0065] D.sub.9 diameter of roll 9 [0066] D.sub.10 diameter
of roll 10 [0067] D.sub.11 diameter of roll 11 [0068] D.sub.12
diameter of roll 12 [0069] D.sub.13 diameter of roll 13 [0070]
D.sub.14 diameter of roll 14 [0071] D.sub.15 diameter of roll 15
[0072] D.sub.16 diameter of roll 16 [0073] D.sub.17 diameter of
roll 17 [0074] v speed of conveyance
* * * * *