Note: Descriptions are shown in the official language in which they were submitted.
CA 0206~801 1999-01-14
BACKGROUND OF THE lNv~NllON
Field of the Invention
The present invention relates to a tension roller
leveler, and more particularly to a tension roller leveler
capable of high-speed treatment.
Prior Art
As an apparatus for reforming strip plates or
sheets, there has been conventionally known, by way of
example, a tension leveler in combination of extension rolls
20 and succeeding anti-cambering rolls 21 as shown in Fig. 4,
or an apparatus including a roller leveler 22 which is located
down-stream of such a tension leveler and comprises a number
of work rolls 1', 2' respectively arranged on the upper and
lower sides of a strip plate S.
In the former tension leveler, however, sensitivity
is so high that a curl (longitudinal curvature~, particularly,
is changed to a large extent upon a small amount of
penetration, as shown in Fig. 6. This results in the
necessity of delicate control and hence difficulties in
achieving a stable levelling effect.
In the latter apparatus, sensitivity is not so sharp
as the former tension leveler, as shown in Fig. 7, meaning
that a stable levelling effect can be attained relatively
easily in a control sense. Although the
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1 latter apparatus is superior to the former tension
leveler from that point of view, the roller leveler 22
inherently requires not only a number of the work rolls
1', 2' having a relatively small diameter, but also
backup rolls 3', 4' for respectively supporting those
work rolls 1', 2'.
Because the backup rolls 3', 4' need to have
sufficient strength to prevent the work rolls 1', 2' from
bend, their diameter must be remarkably larger than that
of the work rolls 1', 2'.
With the work rolls 1', 2' arranged closely to
each other, therefore, an installation space enough to
accommodate the backup rolls 3', 4' cannot be secured.
For that reason, it is usual that intermediate roll 3' or
4' is disposed in a strA~ling relation to plural (two)
work rolls 1' or 2' so as to support the p}ural (two)
work rolls by an int~ -~iAte roll. Alternatively, as
disclosed in Japanese Patent Publication No. 48-44629,
work rolls are independently supported by intermediate
and backup roll arranged with a spacing therebetween in
the lengthwise direction of the work rolls. More speci-
fically, two rows of backup roll pairs are arranged at
positions different from each other in the lengthwise
direction of the work rolls such that one pair (group) of
backup rolls support one work roll in an independent
manner and the other pair (group) of backup rolls support
another work roll, adjacent to the one work roll, in an
independent manner.
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1 Generally, while the above-described tension
leveler can relatively easily 1~ ve such deformation as
edge waves and center buckles of treated materials
(strip) through its levelling process, there occur a curl
and a cross bow (gutter) by bending under tension, which
residual curvatures remain even after levelling.
To remove those residual curvatures, therefore,
the strip is sub~ected to a roller leveler under a low-
tension or no-tension state.
Meanwhile, recent frequent use of those metal-
lic strips, which are thin and hard material, has
provided that the cor.~entional roll arrangement cannot
satisfactorily remove such residual curvatures.
Where a strip plate has a thickness of 0.15 mm
and a yield stress of 60 kgf/mm2, for example, a roller
leveler requires work rolls having a diameter of about 16
mm. But, the roller leveler comprised of the so many and
thin work rolls encounters difficulties in reforming at a
high speed over 300 mpm. In high-speed lines, the dia-
meter of each work roll is usually desirable to be in arange of about 30 to 40 mm from the s~Andpoints such as
of maint~ining the roll accuracy and ensuring the roll's
service life.
In the case of handling the thin and hard
strip, however, the roller leveler comprised of the work
rolls having a diameter in a range of about 30 to 40 mm
cannot produce any plastic strain due to bending and thus
cannot offer any effect in reforming residual curvature,
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1 as will be seen from Fig. 8.
On the other hand, it is also known that even
; in the thin and hard strip, a plastic strain effect can
be attained by applying a tension and also imposing a
deformation due to bending under the tension, as will be
seen from Fig. 9.
However, since the adjacent work rolls are
contacted and coupled with each other via the backup roll
as shown in Fig. 5 and a plastic elongation caused by
that roller leveler produces a corresponding speed
difference between portions of a strip held in contact
with the inlet side work roll and the outlet side work
roll, such a speed difference appears as a relative slip
at any location in the roller leveler.
~he above relative slip due to a plastic
elongation practically gives rise to few trouble in
levelling at low-speed less than 300 mpm as practiced
col.Yel~tionally and, especially, no problem in equipment
where the reforming is carried out under a wet condition
using a cleaning liquid or the like.
On the contrary, when the levelling is carried
out in a high-speed range not less than 300 mpm, particu-
larly, under a dry condition, the above relative slip due
to a plastic elongation generates abnormal noise and
causes damages, called chatter marks or scratch marks, on
the strip, whereby the surface state of the strip is so
~reatly deteriorated as to impair its commercial value.
Fig. 10 shows the relationship between a line
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1 speed and a noise level in the roller leveler of the type
that one backup roll is disposed in a straddling relation
to a plurality of work rolls as shown in Fig. 5. As will
be seen from Fig. 10, when the line speed is regulated to
increase, abnormal noise due to resonation has occurred
in a range exceeding 500 mpm. Conversely, when the line
speed is regulated to decrease, abnormal noise due to
resonation has occurred until lowering down to 400 mpm.
Note that although the occurrence of such abnormal noise
is fluctuated to some extent depending on the size of the
strip S, surface roughness and other properties, a
similar tendency appears under any conditions.
Meanwhile, where work rolls are independently
supported by two groups of backup rolls arranged with a
spacing therebetween in the lengthwise direction of the
work rolls as disclosed in the above-cited Japanese
Patent Publication No. 48-44629, the foregoing problem of
the relative slip due to a plastic elongation will not
occur, but there produces a difference in press force
between the portion where the work rolls are supported ~y
the backup rolls and the portion where they are not
supported by the backup rolls because the work rolls are
simply supported by the backup rolls at different
positions from each other in the lengthwise direction of
the work rolls. Such a difference appears as line~r
flaws on the surface of the strip, which impairs its
commercial value.
CA 0206~801 1999-01-14
SUMMARY OF THE lNV~NllON
An object of the present invention is to provide a
tension roller leveler by which stable curl and gutter
reforming can be performed even in a high-speed range not less
than 300 mpm without causing abnormal noise and vibration,
while ensuring superior surface condition of a strip and final
products with a high commercial value.
The present invention provides a tension roller
leveler comprising an upper frame for mounting a plurality of
upper work rolls thereon, a lower frame for mounting a
plurality of lower work rolls thereon in opposite relation to
said upper work rolls, bridle rolls disposed on the inlet side
and the outlet side of a path line of a strip formed between
the row of said upper work rolls and the row of said lower
work rolls, and means for regulating the vertical position and
the inclination of said upper frame relative to said lower
frame, wherein said work rolls are each supported
independently by one set of backup rolls in two rows over the
substantially entire length thereof, and said backup rolls in
two respective rows are arranged in a zig-zag pattern such
that axial positions of shaft support portions of said backup
rolls in two respective rows do not overlap with each other in
view of the direction of said path line.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic side view of an embodiment of
the present invention.
Fig. 2 is a schematic plan view showing an
arrangement of backup rolls in the present invention.
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1 Fig. 3 is a side view of a roller leveler unit
in the present invention.
Fig. 4 is a schematic side view of a conven
tional tension leveler.
Fig. 5 is a schematic side view of a combina-
tion of a conventional tension leveler and roller
leveler.
Fig. 6 is a graph showing the relationship
between an amount of penetration and an amount of
residual curvature in the conventional tension leveler.
Fig. 7 is a graph showing the relationship
between an amount of penetration and an amount of
residual curvature in a combination of the conventional
tension leveler and roller leveler.
Fig. 8 is a graph showing stress distribution
when a strip plate is subjected to ben~ing under no
tension.
Fig. 9 is a graph showing stress distribution
when a strip plate is sub~ected to bending under ten~ion.
Fig. 10 is a graph showing the relationship
between a line speed and a noise level in the conven-
tional tension roller leveler.
DE~ATT~n DESCRIPTION OF PREFERRED EMBODIMENT
Hereinafter, an embodiment of the present
invention will be described with reference to Figs. 1 to
3.
As shown in Fig. 1, upper work rolls la, lb and
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1 lower work rolls 2a, 2b arranged on the upper and lower
sides of a strip S are supported to an upper roll support
5 and a lower roll support 6 via backup rolls 3a, 3b and
4a, 4b, respectively.
The upper work rolls la, lb and the lower work
rolls 2a, 2b are each separately supported by a pair of
backup roll rows 3a, 3b and 4a, 4b, respectively. More
specifically, as shown in Fig. 2, the backup roll rows
3a, 3b and 4a, 4b each comprise a plurality of rolls
divided in the lengthwise direction of the work rolls la,
lb, 2a, 2b and joined to each other via bearing members
(not shown) disposed between every adjacent divided rolls
such that the total length is substantially equal to the
length of the work rolls la, lb, 2a, 2b. A pair of every
two backup roll rows 3a, 3b or 4a, 4b separately ~up~o Ls
each of the upper or lower work rolls la, lb or 2a, 2b in
an independent manner, respectively.
Then, the pairs of two backup roll rows 3a, 3b,
or 4a, 4b are arranged in a zig-zag pattern so that the
bearing members of ones of the paired backup roll rows 3a
or 3b, 4a or 4b will not overlap with the bearing members
of the other counter-part backup rolls.
The upper roll support 5 and the lower roll
support 6 are fixed to an upper frame 7 and a lower frame
8, respectively, either one of which (the lower frame 8
in this embodiment) is supported in a movable manner.
More specifically, the lower frame 8 is sup-
ported at its lower surface by rods lla, llb which are
CA 0206~801 1999-01-14
movable up and down by worm jacks lOa, lOb, respectively,
carried on a base 9 whereby the lower frame 8 can be moved
vertically and also tilted upon actuation of the worm jacks
lOa, lOb. Accordingly, the work rolls la, lb, 2a, 2b can be
controlled to desirably adjust an amount of closing and
opening degrees (penetration) of the inlet side work roll and
the outlet side work roll.
Denoted at 12a, 12b are rollers rotatably supported
on the opposite sides of the lower frame 8. These rollers
12a, 12b are arranged to respectively rest on rails 13a, 13b
when the lower frame 8 is descended, thereby allowing the
lower frame 8 to move laterally (in a direction normal to the
drawing sheet of Fig. 3).
Denoted at 14a, 14b (Figure 1) are bridle rolls
respectively disposed on the inlet side and the outlet side of
the work rolls la, lb, 2a, 2b for applying a predetermined
tension to the strip S.
While the number of the work rolls la, lb, 2a, 2b is
illustrated in this embodiment to be eleven in total, i.e.,
five for the upper work rolls plus six for the lower work
rolls, the number of the work rolls may be of any desired one
so long as the number of the upper work rolls is one more (or
less) than that of the lower work rolls and the total number
of both the work rolls is not less than five.
Further, it is desirable that the work rolls la, lb,
2a, 2b have their diameters which are so selected as to
gradually increase from the inlet side toward the
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1 outlet side of the roller leveler for the purpose of
gradually decreasing the curvature of bending of the
strip S.
Operation of this embodiment will now be
described.
The strip S is moved to pass through the work
rolls la, lb and 2a, 2b while undergoing a predetermined
tension from the bridle rolls 14a, 14b.
Accordingly, the strip S is repeatedly sub-
jected to bending under the tension and thus deliveredfrom the inlet side toward the outlet side of the roller
leveler while causing an elongation due to plastic
strain, as explained above in connection with Fig. 9.
Therefore, the path length of the strip S is
changed between the every two work rolls adjacent to each
other. With the present invention, however, the adjacent
work rolls are each separately supported by a corre-
sponding pair of backup roll rows so that the individual
work rolls la, lb, 2a, 2b are rotatable in an independent
manner.
If the ad~acent work rolls are supported by a
cc ~n single backup roll as with the prior art, those
ad~acent work rolls are held in slide contact with each
other and the rotation of one work roll is mechanically
fed back to the other work roll, thereby causing both the
work rolls to be forced to rotate at the same speed. For
that reason, where an extension of thé strip S occurs
be~ween both the work rolls, a relative slip is
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1 necessarily caused at any location in the roller leveler
unless a speed difference corresponding to the amount of
such an elongation is provided. In contrast, with the
present invention, the adjacent work rolls are mechani-
cally separated from each other and separately rotatable,resulting in no possibility of the occurrence of such a
relative slip.
As described above, according to the present
invention, since work rolls are each supported by one
pair of backup rolls, even if a strip is repeatedly
subjected to bending under tension in a tension leveler
and thus extended so as to change the path length between
the adjacent work rolls, the work rolls and the backup
rolls can be rotated in an independent manner, whereby no
relative slip is caused at any location in the tension
leveler for absorbing an extension of the strip between
the adjacent work rolls unlike the conventional tension
roller leveler. Consequently, while the relative slip
has produced abnormal noise due to abnormal resonation
and has resulted in flaws called chatter marks in a
conventional high-speed treatment line, any such abnor-
mality will not occur in the present invention.
Further, although the backup rolls are each
formed by joining a plurality of rolls to each other in
the lengthwise direction of the work rolls, a pair of
backup rolls are arranged in a zig-zag pattern such that
the bearing members of the divided rolls of one backup
roll will not overlap with the bearing members of the
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1 divided rolls of the other. Therefore, the joints
between the divided rolls of each backup roll will not be
transferred to the surface of the strip via the work roll
to appear as linear flaws~ As a result, the tension
roller leveler with superior stability in a high-speed
range can be obtained.
