Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rolling mill stand
for cold-rolling and hot-rolling of flat material,
particularly for reducing and temper-rolling metal strip.
The rolling mill stand includes two cambered work rolls and
back-up rolls for the work rolls.
2. Description of the Related Art
In order to change the camber in the roll gap, it is
known in the art, for example, to axially displace
appropriately shaped work rolls. However, it is also known
in the art to prebend the back-up rolls for the work rolls
and to horizontally bend driven intermediate rolls. Also
known is the adjustment of a shell-type roll by varying the
hydraulic pressure between the roll shell and the roll body.
However, the known adjustments are usually cumbersome and
expensive.
SUMMARY OF THE INVENTION
; Therefore, it is the object of the present invention to
provide a rolling mill stand of the above-described type in
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which the camber in the roll gap can be continuously adjusted
during the rolling process in a simple and quick manner.
In accordance with the present invention, the above
object is met in a rolling mill stand of the above-described
type by providing two back-up rolls each for the lower work
roll and/or for the upper work roll. For the continuous
adjustment of the back-up aGtion, the back-up rolls are
mounted so as to be swingable. Preferably, the back-up rolls
are mounted so as to be swingable on a circular path around
the center of the lower work roll or the upper work roll,
respectively.
The features of the present invention make it possible
that bending and, thus, cambering of the lower work roll
and/or upper work roll can be continuously adjusted in
dependence on the respective rolling force by a swinging
movement of the respective back-up rolls, so that always a
uniform roll gap is realized. The camber of the work rolls
is provided in accordance with 100% of the maximum rolling
force, so that when the rolling force is reduced the bending
of the lower work roll and/or upper work roll can be adjusted
in such a way that the sum of the bending deformations at the
upper and lower work rolls corresponds to the sum of the
cambers which have been utilized.
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Two back-up rolls are preferably provided only for the
lower work roll. In this case, the upper work roll is
supported in the known manner by only a single back-up roll
and is equipped with an adjusting system. If it is assumed
that the upper back-up roll and the two lower back-up rolls
have the same diameter and the two lower back-up rolls are
arranged at an initial angle of 45~ relative to the center of
the lower work roll, the diameter ratio of back-up rolls to
work rolls is approximately 2.4. In this assumed initial
position of 45, the two lower back-up rolls have the same
supporting effect as the single upper back-up roll. By
swinging the two lower back-up rolls apart, an increased
spreading effect is obtained which, however, permits an
increased bending of the lower work roll in order always to
provide a correction of the bending line and, consequently,
cambering of the roll to obtain an ideal roll gap.
In the event that larger back-up rolls are required, for
example, when a larger control range is necessary, the
present invention provides that at least one intermediate
roll is provided between outer back-up rolls and the lower
work roll and/or the upper work roll, wherein at least two
back-up rolls are mounted so as to be swingable on a circular
path around the center of the intermediate roll for these
back-up rolls in order to obtain a continuous adjustment of
the back-up effect. It is essentially also possible to
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vertically adjust the entire rolling mill stand for adjusting
the pass line.
In accordance with a preferred embodiment of the
invention, the back-up rolls are mounted with segment-like
bearing blocks on rolling bodies which, in turn, are mounted
on semi-cylindrical bearing shells. It is also possible to
mount the back-up rolls in sliding or hydrostatic bearing
shells. The described features make it possible to easily
swing the back-up rolls. This is particularly true if
adjusting drives, for example, hydraulically or pneumatically
operated cylinder-piston arrangements or mechanically
actuated spindles, are hinged to the housings of the rolling
mill stand.
The present invention further provides that the back-up
rolls and possibly the intermediate rolls and the adjusting
drives are arranged symmetrically relative to a vertical axis
of symmetry extending through the work rolls. As a result,
the back-up rolls can be swung by means of the adjusting
drive either individually or together through an equal or
unequal angle. This makes possible a continuous adjustment
of the camber for each rolling procedure, even if the rolled
material is not to be reduced but is only to be temper-
rolled.
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The present invention also relates to a method for
changing the ca~ber of a work roll supported by means of two
back-up rolls in the roll gap during the rolling procedure in
dependence on the respective rolling force. The method
includes continuously changing the back-up effect by swinging
the two swingably mounted back-up rolls by an angle which is
predetermined by the respective rolling force, so that the
sum of the bending of the upper work roll and the lower work
roll corresponds to the sum of the non-utilized cambers.
The various features of novelty which characterize
the invention are pointed out with particularity in the
claims annexed to and forming a part of this disclosure. For
a better understanding of the invention, its operating
advantages attained by its use, reference should be had to
the drawing and descriptive matter in which there are
illustrated and described preferred embodiments of the
invention.
BRIEF DESCRIPTION OF THE DRAWING
In the drawing:
Fig. 1 is a schematic side view of the rolling mill
stand according to the present invention;
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Fig. 2 is a front elevational view of the rolling mill
stand of Fig. l;
Fig. 3 is a schematic illustration of the arrangement of
the work rolls and back-up rolls of the rolling mill stand of
Fig. l;
Fig. 4 is a schematic illustration of another embodiment
with two back-up rolls for the lower work roll and the upper
work roll;
Fig. 5 is a schematic illustration of another embodiment
with an intermediate roll;
Fig. 6 is a schematic illustration of the rolls of Fig.
3 with the lower back-up rolls being swung by 60;
Fig. 7 shows the elastic bending of the rolls in a
position swung by 45;
Fig. 8 shows the elastic bending of the rolls in a
position swung by 60; and
Fig. 9 shows the arrangement of rolls according to the
present invention in a multiple-roll rolling mill stand.
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DESCRIPTION OF THE PREFERRED EMBODIMENTS
The figures of the drawing show a rolling mill stand 1
for cold-rolling and hot-rolling of flat material,
particularly for reducing and temper-rolling of metal strip.
The rolling mill stand 1 is essentially composed of two
cambered work rolls 2a, 2b and back-up rolls 3, 4 for the
work rolls.
As shown in Fig. 3, two back-up rolls 4a, 4b are
provided for the lower work roll 2b. However, as shown in
Fig. 4, it is also possible to provide two back-up rolls 3a,
3b additionally for the upper work roll.
The two back-up rolls 3a, 3b or 4a, 4b are mounted so as
to be swingable on a circular path B about the center M of
the lower or upper work roll 2a, 2b for the continuous
adjustment of the support effect.
As shown in Fig. 5, the back-up rolls 4a, 4b are
supported in segment-like bearing blocks 5. The segment-like
bearing blocks 5 are mounted so as to be swingable in a semi-
cylindrical bearing shell 7 on rolling bodies 6. Adjusting
drives 8 are hinged to the bearing blocks 5 and to the
housings of the rolling mill stand 1. In the illustrated
embodiment, the adjusting drives 8 are hydraulically operated
cylinder-piston arrangements.
; 8
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In accordance with another embodiment illustrated in
Fig. 5 of the drawing, an intermediate roll 9 is mounted
between the lower work roll 2b and the two back-up rolls 4a,
4b. In this case, the back-up rolls 4a, 4b are mounted so as
to be swingable along a circular path B1 about the center M
of the intermediate roll 9 in order to obtain a continuous
adjustment of the support effect.
The back-up rolls 3a, 3b or 4a, 4b and, if provided, the
intermediate roll 9 as well as the adjusting drives 8 are
arranged symmetrically relative to a vertical axis of
symmetry S extending through the work rolls 2a, 2b. The
back-up rolls 3a, 3b or 4a, 4b can be swung by means of the
adjusting drives 8 individually or together through an equal
or unequal angle ~. Swinging of the two lower back-up rolls
4a, 4b (and of the two upper back-up rolls, if provided)
always results in a eontinuous adjustment of the eamber of
the work rolls 2a, 2b in the roll gap during the rolling
proeedure in a simple and quiek manner.
Figs. 7 and 8 of the drawing show the elastie bending
behavior of the rolls at swung positions of 45 and 60,
respectively. For clarity's sake, the work rolls 2a, 2b
which are actually cambered and the back-up rolls 3, 4a, 4b
are shown cylindrically and the illustration of the elastie
g
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bending is exaggerated. As can be seen, the elastic bending
11 is greater in the 60 position than the bending 10 in the
45 position.
When appropriately taking into consideration the roll
diameters, the teaching of the present invention can also be
utilized in multiple-roll rolling mill stands. For example,
the 20-roll rolling mill stand shown in Fig. 9 has eight
back-up rolls 3, 4 of which always two lower and two upper
back-up rolls 4a, 4b and 3a, 3b are mounted so as to be
swingable about the center M1 of the respective intermediate
roll 9 in order to obtain a continuous adjustment of the
support effect.
In addition, it is possible to deviate from the ideal
circular path about the center of the contacting roll when
the back-up rolls are swung if the resulting error in the
spacing between the work rolls is compensated by means of the
roll adjusting system. In this manner, instead of using
shims, the wear or abrasion of the rolls can be compensated.
The drive of the rolling mill stand can be provided in the
conventional manner on the work rolls or the back-up rolls.
Also, the rolling action can be aided by appropriate
tensioning units in front of and behin~ the rolling gap.
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While specific embodiments of the invention have been
shown and described in detail to illustrate the inventive
principles, it will be understood that the invention may be
embodied otherwise without departing from such principles.
