U.S. patent application number 16/336519 was filed with the patent office on 2021-11-11 for method and apparatus for stretch-bend leveling metal strip.
The applicant listed for this patent is Andreas NOE. Invention is credited to Andreas NOE.
Application Number | 20210346930 16/336519 |
Document ID | / |
Family ID | 1000005697319 |
Filed Date | 2021-11-11 |
United States Patent
Application |
20210346930 |
Kind Code |
A1 |
NOE; Andreas |
November 11, 2021 |
METHOD AND APPARATUS FOR STRETCH-BEND LEVELING METAL STRIP
Abstract
The invention relates to a method and to a device for the
stretch-bend leveling of a metal strip (B), wherein the metal strip
(B) is alternately bent around stretching rollers (1-5) under a
tensile stress and the degree of stretching is thus increased,
wherein one or more stretching rollers (1-5) are provided with a
non-metal coating. The method and the device are characterized in
that one or more stretching rollers are provided with a coating (8)
of plastic.
Inventors: |
NOE; Andreas; (US) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NOE; Andreas |
|
|
US |
|
|
Family ID: |
1000005697319 |
Appl. No.: |
16/336519 |
Filed: |
September 25, 2017 |
PCT Filed: |
September 25, 2017 |
PCT NO: |
PCT/EP2017/074210 |
371 Date: |
March 26, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B21D 1/05 20130101 |
International
Class: |
B21D 1/05 20060101
B21D001/05 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 9, 2016 |
DE |
102016121448.5 |
Claims
1. A method of stretch-bend leveling metal strip, the method
comprising the steps of: bending the metal strip alternately around
a plurality of stretching rollers under a tensile stress, and
increasing the stretching rate in a downstream strip-travel
direction, providing one or more stretching rollers with a plastic
jacket.
2. The method according to claim 1, further comprising the steps
of: passing the metal strip through an inlet tension roller set for
establishing tension and through an outlet tension roller set for
dissipating the tension, the strip is bent alternately around the
stretching rollers between the inlet tension roller set and the
outset roller set, and the stretching rate of the strip being
increased in the strip-travel direction.
3. The method according to claim 1 wherein each of the stretching
rollers is provided with a respective jacket of plastic.
4. The method according to claim 1, wherein the jacket consists of
polyurethane.
5. The method according to claim 1, wherein the jacket has a Shore
A hardness of at least 90.
6. The method according to claim 1, wherein the metal strip passes
through the stretching rollers in dry operation without any spray
medium or the like being sprayed onto the stretching rollers.
7. The method according to claim 1, wherein an angle of wrap around
the stretching rollers is adjusted as a function of strip tension
so that a maximum linear load applied to the jacket is not
exceeded.
8. The method according to claim 1, wherein a stretching rate of at
least 0.2% is produced by the stretching rollers.
9. The method according to claim 1, wherein the strip is under a
tensile stress of at least 15% of the yield point of the metal
strip.
10. The method according to claim 1, wherein the jacket is at least
1 mm thick.
11. The method according to claim 1, wherein the stretching rollers
each have a diameter of 25 mm to 100 mm.
12. The method according to claim 1, further comprising the step
of: supporting each of the stretch rollers individually.
13. The method according to claim 1, further comprising the step
of: adjusting one or more or all of the stretching rollers
individually.
14. The method according to claim 1, wherein three to five
stretching rollers are provided between the inlet tension roller
set and the outlet tension roller set.
15. The method according to claim 1, further comprising the step
of: supporting the stretching rollers are each supported
individually on at least two backing or intermediate rollers.
16. The method according to claim 15, further comprising the step
of: providing the backing rollers or the intermediate rollers also
provided with a jacket of plastic.
17. An apparatus for stretch-bend leveling metal strip the
apparatus comprising: an inlet tension roller set for establishing
strip tension, an outlet tension roller set for releasing the strip
tension, a plurality of stretching rollers between the inlet
tension roller set and the outlet tension roller set, the to strip
being bent in alternation around the stretching rollers with an
increase in the stretching rate, a plastic jacket on one or more
stretching rollers.
18. The apparatus according to claim 17, wherein the jacket is of
polyurethane
19. The method according to claim 1, wherein the jacket is 3 mm to
7 mm thick.
Description
[0001] The invention relates to a method of stretch-bend leveling
metal strip where the metal strip is alternately bent around
stretching rollers (of a stretch bending frame) thereby creating
the stretching rate and/or increasing it, such that one or more
stretching rollers made of metal, for example, are provided with a
nonmetallic coating (on the circumference) and consequently are
provided with a jacket. In doing so the strip usually passes
through an inlet tension roller set to establish the tension and an
outlet tension roller set to release the tension, such that the
strip is alternately bent around the stretching rollers between the
inlet tension roller set and the outlet tension roller set, thereby
creating and/or increasing the stretching rate.
[0002] With such a stretch-bend leveling method, uneven metal
strips can be leveled, and consequently, nonplanarity can be
eliminated. Unevenness refers to strip waviness and/or strip
warping, for example, which is/are the result of differences in the
length of the strip fibers in the plane of the strip. Within the
context of the present invention, such unevenness is to be
differentiated from strip warping in the longitudinal and/or
transverse direction(s), which results from bending torques in the
strip, for example, when elastic-plastic deformation of the strip
occurs in bending around deflecting rollers and when
elastic-plastic deformation of the strip occurs in winding.
Longitudinal warping is also referred to as coil set, while
transverse warping is known as cross bow.
[0003] Following stretch-bend leveling, the uneven strip is bent
around rollers of a small enough diameter (alternately) with a
tensile stress that is below the limit of elasticity RE and/or the
technical elasticity limit RP0.01 of the strip material, so that
elastic-plastic deformation is created in the strip by
superimposing the bending on the tensile stress. The strip is
elongated with plastic deformation, so that the level of plastic
elongation is referred to as the stretching rate. In plastic
elongation, strip fibers that were originally short are lengthened
to a relatively great extent. In the ideal case, all the strip
fibers are of the same length after stretch-bend leveling, so that
basically an ideally leveled strip that is free of waviness or
strip curl is formed.
[0004] In practice, such a stretch-bend leveling method is usually
carried out with a stretch-bend leveling apparatus having at least
one stretch bending frame. Such a stretch bending frame will in
practice often have three or five stretching rollers.
[0005] Within the scope of the present invention, the term
"stretching rollers" preferably refers to stretching rollers
supported individually (on backing rollers), and optionally one or
more stretching rollers may be individually adjustable. To this
extent, such a stretch-bending frame with its stretching rollers is
to be differentiated from a multiroller leveling unit of the type
that is also known per se but usually has one fixed cassette and
one adjustable cassette, each having a plurality of leveling
rollers and backing rollers. The leveling rollers are usually
coupled to one another in a friction-drive manner by the backing
rollers in the respective cassette within such a multiroller
leveling unit, i.e. all the leveling rollers (of a cassette) rotate
at the same speed. In such a multiroller leveling unit, residual
warping is usually eliminated in such a way that the strip is not
usually under a tensile stress or is under just a slight strip
tension in the multiroller leveling unit. No "global" stretching
rate is produced.
[0006] Stretch-bend leveling according to the invention is
therefore to be differentiated from elimination of residual strip
warping in a multiroller leveling unit (with little or no strip
tension and without creating any significant stretching rate). A
stretching rate of at least 0.2% is usually produced with the
stretching rollers and/or with the stretch-bend leveling frame. The
strip is usually under a tensile stress of at least 15%, preferably
at least 20%, of the yield strength of the metal strip.
[0007] It should also be pointed out that, in practice, the metal
strip will not always be completely clean on entering the
stretch-bend leveling installation and/or the stretch-bend frame.
The surface of the strip is often soiled or coated with a film of
residual rolling oil. Furthermore, the metal strips often processed
in practice are aluminum strips that have been provided with a
surface oxide layer, but during extreme bending around the
stretching rollers in stretch-bend leveling, this oxide layer
ruptures, thereby releasing oxide particles from the surface of the
strip. In practice, the stretching rollers in stretch-bend leveling
are usually provided with a metal surface, such as hardened steel.
Particles of dirt and/or oxide may adhere to these roller surfaces,
on which they may gradually build up, resulting in vibrations,
which in turn cause unwanted chatter marks on the strip.
[0008] To prevent dirt and/or oxide particles from adhering to the
rollers and the problems associated therewith, it is customary in
practice to operate the stretch-bend leveling process as a wet
operation. The strip and possibly also the stretching rollers and
backing rollers are sprayed with a spray medium or treated in some
other way at the inlet end. The problematical particles are washed
off in this way, and a buildup of particles on the rollers is
prevented. Water-based media are used in practice here as the spray
media. One disadvantage is that the strip here must be completely
cleaned and dried before winding because otherwise the residual
moisture would result in corrosion damage in the wound coil.
Alternatively, solvent-based spray media, for example
kerosene-based media, may be used. Evaporation of the solvent here
is a disadvantage, so that suction ventilation must be provided,
and it may be necessary to scrub the exhaust air. Furthermore,
fire-prevention equipment must be provided because such solvent
vapors are flammable.
[0009] Another disadvantage of using spray media is that a strip
with the residual moisture may have a tendency to slip on the
tension rollers of the outlet tension roller set. As a result, the
tension rollers can only be designed with lower transmission
factors.
[0010] Alternatively, EP 0 276 614 proposes that the stretching
rollers in the stretch-bend leveling process should be provided
with a jacket of a ceramic material, namely with a composition that
not only has an adequate hardness but also has a very low
wettability with regard to liquids in order to prevent metal strip
jacket particles and oxide particles from adhering to the roller.
Production of the ceramic layer may be based on aluminum oxide, for
example. In practice, however, implementation of such
stretch-bending rollers with a ceramic jacket has posed substantial
problems.
[0011] Against this background, the object of the present invention
is to create a method and an apparatus for stretch-bend leveling
metal strip of the type described in the introduction, which will
make it possible to manage the process as a dry operation in a
structurally simple manner.
[0012] To achieve this object, the present invention teaches that
the stretch rollers should be provided with a jacket of plastic in
a generic method and with an apparatus for stretch-bend leveling
metal strip. Within the scope of the invention, the term "plastic"
refers to a polymer material, in particular a synthetic polymer
material including rubber. It is preferably a jacket of
polyurethane or a comparable plastic. Alternatively, for example, a
jacket of polyamide may also be used.
[0013] Plastic jackets are usually already known in practice in
conjunction with tension rollers and deflecting rollers used to
optimize friction, for example, and thus improve the transmission
factors, or to protect the strip surfaces. For stretch rollers in
stretch-bend leveling, in which the strip is under a tensile stress
of usually at least 15% of the yield strength of the metal strip,
preferably at least 20%, and in which a stretching rate of at least
0.2% is created by using the stretching rollers, the use of such
plastic jackets, for example polyurethane jackets, has not
previously been considered. It has now surprisingly been found that
instead of the usual stretching rollers made of steel, stretching
rollers with a polyurethane jacket, for example, can be used for
stretch-bend leveling of aluminum strips, for example.
Consequently, such stretching rollers preferably consist of a
roller core made of metal, for example, steel, and a jacket of
plastic, for example, polyurethane. With such a jacket, the
stretch-bend leveling process can be carried out as a dry process.
It has surprisingly been found that although the stretching rollers
initially become soiled, the degree of soiling stabilizes at a
level that allows dry operation without resulting in any strip
surface damage. It is thus possible to eliminate the spray systems
that are used in practice, so that the associated disadvantages are
avoided. In contrast with the ceramic jackets proposed in the prior
art, plastic jackets, in particular polyurethane jackets, can be
produced easily and inexpensively, and it has surprisingly been
found that the angle of wrap around the stretching rollers can be
set to be low enough that the maximum allowed linear load for the
jacket is not exceeded, depending on the strip tension. Although
there have been some fears in conjunction with polyurethane
surfaces, namely that the segmented backing rollers or intermediate
rollers, for example, might produce impressions on the polyurethane
surface have not been confirmed. Despite a very high required strip
tension for the desired stretching rate, the resulting linear load
on the stretching roller is low enough on the whole and is less
than the maximum load allowed for the polyurethane jacket. In
addition, a plastic jacket, for example, a polyurethane jacket,
also has a certain vibration-damping effect, so that vibrations and
chatter marks are minimized or prevented. Soiling of the backing
rollers, which usually occurs in practice, is not observed in dry
operation.
[0014] It is therefore possible on the whole to satisfactorily
process metal strips in a dry operation and without any damage to
the surface.
[0015] Use of a plastic jacket in a multiroller leveling unit is
described in the prior art according to JP63-199023 and
JP63-199024. In such a "roll leveler," the metal strip is usually
not under little or no strip tension, and there is also no
noticeable stretching rate, so that there are only very low loads
on the rollers and the jackets. Protection of the metal strip by
the plastic jacket is the main concern, so that damage to the strip
should be prevented. Against this background, the invention is
based on a different idea. Within the scope of the present
invention, a jacket with a Shore A hardness of at least 90 is
preferably used. The jacket may be at least 1 mm thick, preferably
at least 3 mm thick. It is therefore possible to use a 1 mm
thickness to 10 mm thickness, for example preferably 3 mm to 7 mm.
The stretch rollers preferably have a diameter of 25 mm to 100 mm,
for example, 35 mm to 70 mm. The diameter refers to the core, i.e.
these values do not include the plastic jacket.
[0016] The stretching rollers are each supported individually in
stretch-bend leveling and/or in a stretch-bend leveling frame, i.e.
they can each be supported individually on at least two backing
rollers and optionally a plurality of intermediate rollers. In
contrast with a multiroller leveling unit, the individual
stretching rollers (for example below or above the strip) are not
connected to one another in a friction-drive manner by the backing
rollers but instead are supported individually, so that they can
rotate at different speeds. Preferably one or more stretching
rollers can be adjusted individually. For example, there is the
possibility of all stretching rollers being adjustable
individually. Usually, however, it is also possible in the case of
a plurality of stretching rollers to adjust only the lower
stretching rollers with respect to the upper stretching rollers, or
conversely, to adjust the upper stretching rollers with respect to
the lower stretching rollers. Preferably, however, the angle of
wrap on each individual stretching roller is adjustable
individually and independently of the others.
[0017] Coating the stretching rollers with the plastic jacket is
the primary concern of the present invention. In addition, however,
the backing rollers and/or the intermediate rollers may also be
provided with a jacket of plastic, for example, a polyurethane
jacket.
[0018] Aluminum or aluminum alloys strip is preferably used as the
metal strip. However, the present invention also includes the
processing of metal strips of other materials, for example, steel
strips or stainless steel strips.
[0019] The subject matter of the present invention is not only the
method described here but also an apparatus for stretch-bend
leveling of metal strips. The method described here can preferably
be carried out with this apparatus. The apparatus preferably has an
inlet tension roller set for establishing the strip tension and an
outlet tension roller set for releasing the strip tension. A
plurality of stretching rollers, preferably supported individually,
is provided between the inlet tension roller set and the outlet
tension roller set, the strip being bent around each roller in
alternation, increasing the stretching rate. One or more or all of
these stretching rollers are provided with a nonmetallic jacket,
i.e. a jacket, on the roller outer surface. According to the
invention, this jacket is made of plastic, for example,
polyurethane. Specifically, reference is made to the discussion of
the method described here for the preferred embodiment of the
apparatus.
[0020] The present invention is described in greater detail below
with reference to a drawing showing a single embodiment. In the
drawing:
[0021] FIG. 1 is a simplified view of an installation for
stretch-bend leveling metal strip in a simplified diagram,
[0022] FIGS. 2a and 2b are large-scale views of a detail of the
system of to FIG. 1 in various embodiments according to the
invention, and
[0023] FIGS. 3a, 3b and 3c show additional embodiments of the
invention.
[0024] The drawing shows an apparatus for stretch-bend leveling a
metal strip B. The metal strip B may be, for example, an aluminum
strip. However, the invention also comprises stretch-bend leveling
of strips of steel or of other metals or alloys.
[0025] In its basic design, the apparatus has an inlet tension
roller set E for setting the strip tension and an outlet tension
roller set A for releasing the strip tension. A plurality of
stretching rollers 1, 2, 3, 4, 5, about which the strip is bent in
alternation to increase the stretching rate is provided between the
inlet tension roller set E and the outlet tension roller set A.
[0026] Moreover, a deflecting roller U is arranged upstream from
the first stretching roller 1. Another deflecting roller may be
arranged downstream from the last stretching roller.
[0027] Each of these stretching rollers 1 to 5 is supported
individually, namely on at least two backing rollers 6 that are not
shown in FIG. 1. They may be continuous backing rollers or rows of
backing roller segments. At any rate the stretching rollers 1 to 5
are supported individually, i.e. they are not connected to one
another in a friction-locking manner by the backing rollers 6 (in
contrast with a multiroller leveling unit).
[0028] A stretching rate of at least 0.2% is achieved with the
stretching rollers 1 to 5. Tensile stress in the metal strip B is
created during the stretch-bend leveling process with the inlet
tension roller set E and the outlet tension roller set A. The
tensile stress amounts to at least 15% of the yield strength of the
metal strip, preferably at least 20%.
[0029] In the embodiment illustrated here, all stretching rollers 1
to 5 are provided with a nonmetallic jacket 8. Consequently, the
individual stretching rollers consist of a roller core 7 and a
jacket 8. According to the invention, the jacket is a coating of
plastic, preferably polyurethane or a comparable plastic. This
jacket 8 may be 1 mm to 10 mm thick, preferably 3 mm to 7 mm thick.
The stretching rollers 1 to 5 have a diameter of 25 mm to 100 mm,
for example, 35 mm to 70 mm, and the diameter of the stretching
rollers is understood not to include the jacket and consequently
this is the diameter of the roller core 7.
[0030] FIGS. 2a and 2b show embodiments in which only the
stretching rollers 1 to 5 are provided with the plastic jacket 8
according to the invention, while the backing rollers 6 and the
intermediate rollers 6' that are optionally provided do not have a
jacket. FIG. 2a shows an embodiment with two backing rollers 6, and
FIG. 2b shows an embodiment in which intermediate rollers 6' are
additionally provided.
[0031] Against this background, FIGS. 3a, 3b and 3c show
embodiments in which the additional rollers are provided with a
jacket in addition to the stretching rollers 1 to 5.
[0032] FIG. 3a shows an embodiment in which the coated stretching
rollers 1-5 are each supported on two coated backing rollers 6. The
jackets 8' on the backing rollers 6 may also consist of
polyurethane or some other plastic.
[0033] FIG. 3b shows an embodiment in which the stretching rollers
1 to 5 are supported by two intermediate rollers 6' and three
backing rollers 6 and/or three rows of segmented backing rollers.
In this embodiment, the stretching rollers 1 to 5 and the backing
rollers 6 are each provided with a jacket 8 or 8', while the
intermediate rollers 6' are not coated.
[0034] FIG. 3c shows a modification of the embodiment according to
FIG. 3b, and the intermediate rollers 6' here are also provided
with a jacket 8''.
[0035] Metal strips B can be leveled in a dry operation with the
stretch-bend leveling system shown here. In other words, no liquid
is sprayed onto the stretching rollers 1 to 5.
* * * * *