Note: Descriptions are shown in the official language in which they were submitted.
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REEL-UP AND METHOD FOR REGULATION
OF THE NIP PRESSURE TN A REEL-UP
Background of the Invention
This invention relates to a reel-up and a
method for regulation of the nip pressure in a
reel-up.
A known type of reel-up comprises a first
revolving roll or reeling cylinder supported in
stationary bearings in a frame and a second revolv-
ing roll or reeling drum supported on reeling rails
or equivalent. The first and second revolving
rolls together form a nip. The web passes around
the first revolving roll and through the nip, and
7.5 is reeled onto the second revolving roll.
A linear load or nip load is exerted on the
web in the nip. During reeling of the web in a
reel-up, it is generally desirable that the nip
load between the reeling drum and the reeling
cylinder be uniform along the length of the nip,
i.e. in the transverse direction, but it is
difficult to produce a uniform nip load by means
of the prior art methods of reeling, particularly
at the beginning of the reeling, owing to bending
of the reeling drum. Tn so-called primary reeling,
owing to the supporting of the reeling drum, the
nip load is considerably higher at the middle of
the web than at the edges. In so-called secondary
reeling, the loading effect of the reeling forks
produces a higher nip load at the edges of the web
than in the middle.
In the case of some reel-ups, such as Pope-type
reel-ups, in which the reeling drum is changed from
primary rails or arms to secondary rails or arms
during the reeling operation, discontinuities in
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the nip load, such as peaks of nip load, are
readily produced between the reeling cylinder and
the reeling drum during the changeover from the
primary rails to the secondary rails, and these
discontinuities produce broke in the reel bottom,
i.e. in the paper layers near the reel spool.
Summary of the Invention
The object of the present invention is to
provide a reel-up in which the problems mentioned
above do not occur. It is a particular object of
the invention to provide a reel-up in which the
nip load between the reeling drum and the reeling
cylinder is substantially uniform over the length
of the nip. A further object of the invention is
to provide a reel--up in which discontinuities that
produce broke in the reel bottom do not occur.
Tn accordance with a first aspect of the
present invention there is provided a reel-up
comprising a reeling cylinder, means for support-
ing a reeling drum relative to the reeling cylinder
so that the reeling cylinder and reeling drum form
a nip for receiving a web being reeled onto the
reeling drum, and a means for adjusting the relative
positions of the reeling cylinder and the reeling
drum in order to adjust the force acting on the web
in the nip.
In accordance with a second aspect of the
present invention there is provided a method of
operating a reel-up that comprises a reeling
cylinder and means .for supporting a reeling drum
relative to the reeling cylinder so that the reel-
ing cylinder and reeling drum form a nip through
which a web being reeled onto the reeling drum
extends, wherein the method comprises adjusting the
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relative positions of the reeling cylinder and
the reeling drum in order to maintain the force
acting on the web in the nip at a desired value.
In accordance with a third aspect of the
invention there is provided a reel-up comprising
a reeling cylinder, means for supporting a reeling
drum relative to the reeling cylinder so that the
reeling cylinder and reeling drum form a nip for
receiving a web being reeled onto the reeling drum,
and means for applying forces to the opposite ends
of the reeling drum in order to adjust the nip load.
In accordance with a fourth aspect of the
invention there is provided a reel-up apparatus
comprising a reeling cylinder having a vertical
central plane, means for supporting a first
reeling drum relative to the reeling cylinder so
that the reeling drum and reeling cylinder form a
first nip at one side of the central plane of the
reeling cylinder for receiving a web being reeled
onto the first reeling drum, means for adjusting
the relative positions of the reeling drum and
the reeling cylinder in order to adjust the force
acting on the web in the first nip, means for
supporting a second reeling drum relative to the
reeling cylinder so that the reeling cylinder and
second reeling drum form a second nip for receiving
a web being reeled onto said second reeling drum,
the second nip being on the opposite side of the
central plane of the reeling cylinder from the
first nip, and means for adjusting the relative
positions of the reeling cylinder and the second
reeling drum in order to adjust the force acting
on the ~,~reb in the second nip, whereby a web can
be reeled onto the first reeling drum and, upon
completion of reeling onto the first reeling drum,
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the web can be guided to the second reeling drum
and reeled onto the second reeling drum.
According to the invention, the nip load
can be made uniform in the transverse direction
of the machine by supporting the reeling drum
in relation to the reeling cylinder so that the
component of the force of gravity that passes
through the centers of 'the reeling drum and the
reeling cylinder provides the force that is needed
to generate the nip load. By altering the position
of the reeling drum in relation to the reeling
cylinder, the magnitude of the force component~that
produces the nip load is altered and therefore the
nip load itself is altered. Thus, a suitable nip
load is produced by means of the weight of the
reeling drum and of the web reeled onto the drum.
The reeling of the web onto the reeling drum is
started with the reeling drum positioned against
the reeling cylinder at a point such that the
component of the weight of the reeling drum that
is directed at the center of the reeling cylinder
provides a suitable nip load.
Alteration of the force component may be
produced in a number of different ways, for example
by adjusting the inclination of the reeling rails
or forks, As the jumbo roll becomes larger, the
inclination is reduced to a suitable level.
The discontinuities that occur in connection
with the change or transfer from the primary rails
to the secondary rails in a paper reel-up can be
eliminated, according to the invention, for example
by starting the reeling while the reeling drum is
resting on the rails, because it is not then
necessary to move the reeling drum from a primary
reeling position to a secondary reeling position
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and therefore the reeling conditions are stable
and discontinuities and load peaks are avoided.
When the jumbo roll on the secondary rails
is full, the roll is shifted into the braking
5 position, whereupon the primary rails can be
shifted to an optimal inclination for receiving
and reeling a new reeling drum. The inclination
of the primary rails is selected so that the nip
load, i.e. the line pressure, has the desired
value and is uniform across the whole machine in
the transverse direction. When the jumbo roll
becomes larger as the reeling of the new reeling
drum continues, the angle of inclination of the
primary rails is reduced. The change, i.e. the
shifting onto the secondary rails, takes place
by shifting the secondary rails to the same angle
of inclination as the primary rails, whereby the
new reeling drum rolls over the joint from the
primary rails to the secondary rails as reeling
continues, and while the new reeling drum rolls
over the joint the primary rails and the
secondary rails move in synchronized fashion and
regulate the nip load by altering the angle of
inclination.
Also, according to the invention, additional
forces can be applied to the ends of the reeling
drum in a direction perpendicular to the axial
direction of the roll, whereby the nip, load in
the transverse direction of the machine, i.e. in
the axial direction of the reeling drum, can also
be controlled and regulated. If it is desirable,
for example by means of adjustment operations, to
act upon the transverse profile of nip load while
at the same time keeping the overall nip load
unchanged, the angle of inclination can be
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regulated to compensate for the effect of the
additional forces on the overall nip load.
The method of the invention is well suited
for application when the reeling is started
directly from the rails. In such a case it is
possible to make use of regulation of loading
based on the geometry. When the paper roll
formed on the reeling drum becomes larger and its
weight increases, the reeling angle is reduced
and the nip load is maintained at a desired value
or in a desired range of values.
By means of the arrangement in accordance
with the invention, other advantages are also
achieved, For example, at the beginning of
reeling there is no process of exchange, arid the
loading situation is seen naturally by observing
the inclination of the rails. Further, sudden
changes in nip load and in other loads are
avoided, and regulation of the nip load in
accordance with the invention is mechanically
easy, and its control is technically easy.
Brief Description of the Dra~Ninas
In the following, the invention will be
described in more detail with reference to the
figures in the accompanying drawings, the
invention being, however, in no way strictly
confined to said figures. In the drawings:
FIGS. A and B illustrate schematically some
problems of nip load known in the prior art,
FIG. 1 is a schematic illustration of the
reeling process at the initial stage of the
reeling,
FIG. 2 is a schematic illustration of the
reeling process at the final stage of the reeling,
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FIG. 3 is a schematic illustration of an
arrangement in accordance with the invention for
providing a uniform nip load or nip pressure,
FIG. 4 is a schematic illustration of a further
exemplifying embodiment of the invention,
FIG. 5 is a schematic illustration of an
arrangement in accordance with the invention which is
suitable for use in continuous reeling,
FIG. 6 is a schematic illustration of a second
arrangement in accordance with the invention which is
suitable for use in continuous reeling, and
FIG. 7 is a schematic illustration of an
arrangement in accordance with the invention employed
in connection with the process of exchange of reeling
drum.
Detailed Description
As shown in FIG. A, in primary reeling the nip
load between the reeling cylinder 15 (also referred
to as "a first revolving roll") and the reeling drum
20 (also referred to as a "second revolving roll 20"
is higher at the center of the web than at the edges.
The nip load at the center of the web is denoted with
the arrows Z. The higher nip load at the center
results from supporting the reeling drum 20 at its
ends, as denoted schematically with the arrows X.
FIG. B illustrates how, in secondary reeling,
when the reeling drum 20 is forced against the
reeling cylinder 15 for providing the nip load, as
denoted schematically with the arrows XZ in the
figure, there is a higher loading Zz at the edges of
the web than at the center.
The reel-up shown in FIG. 1 comprises a reeling
cylinder 15 and a reeling drum 20, both of which are
revolving, and which form a nip N. The reeling
cylinder 15 is supported in stationary bearings in a
frame 5 and is driven to rotate, e.g. by a motor (not
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shown), and the reeling drum 20 is either driven by
its own motor or is freely rotatable and is driven by
the cylinder 15 through nip contact. In the reel-up
shown in FIG. 1, a web W. e.g. of paper, is fed
around the first revolving roll, i.e. the reeling
cylinder 15, and passes through the nip N and is
reeled onto the second revolving roll, i.e. the
reeling drum 20, which is supported by reeling rails
10.
As shown in FIG. 1, the reeling of the web W
onto the reeling drum 20 against the reeling cylinder
15 is started with the reeling drum at a position
such that the component Gr (also referred to as "a
nip pressure") of the weight G of the reeling drum
acting through the center of the reeling cylinder 15
is within the range of suitable values of the nip
load. In such a case, the nip load effective in the
nip N is substantially uniform across the whole
machine in the transverse direction and is not
excessively high between the ends of the reeling
drum. In FIG. 1, the sense of rotation of the reeling
cylinder 15 is denoted with the reference S1, and the
sense of rotation of the reeling drum 20 with the
reference S2. The component Gr is equal to G*cos R,
where a is the angle between the vertical and the
line through the centers of the rolls.
As shown in FIG. 2, regulation of loading based
on geometry is utilized. As the web roll that is
reeled onto the reeling drum 20 becomes larger, so
that the drum becomes heavier, the angle is increased
so that cos ~ is reduced, and the nip load, as a
proportion of the weight of the reeling drum, is
reduced.
As shown in FIG. 3, the nip pressure at the nip
N can be made uniform in the transverse direction of
the machine, i.e. in the axial direction of the
CA 02054250 1998-10-27
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reeling drum 20, by supporting the reeling drum 20 in
relation to the reeling cylinder 15 so that the
component Gr of the weight G that passes through the
centers of the reeling drum 20 and the reeling
cylinder 15 provides the nip load. The nip load is
regulated by altering the position of the reeling
drum 20 in relation to the reeling cylinder 15 so
that the angular position of the nip N about the
central axis of the reeling cylinder is changed and,
at the same time, the magnitude of the force
component Gr that produces the nip load is altered.
The force component Gr is altered most easily by
adjusting the inclination of the reeling rails 10,
i.e. the angle a. In such a case, the nip load is Gr
- G * sin a, and the weight of the reeling drum 20
and the weight of the web reeled onto the drum
produce the nip load at the nip N. As the jumbo roll
20 becomes larger, the angle a of inclination is, of
course, made smaller, preferably from about 20° to
1°, to maintain a constant nip load.
The angle a of inclination of the reeling rails
10 is adjusted by means of an actuator, e.g. a screw
jack 30 or a cylinder or some other corresponding
member, which may also be referred to, in general
terms, as "a member for alteration of the positions
of the first revolving roll and the second revolving
roll in relation to one another." A great number of
well-known arrangements are suitable for adjustment
of the angle a of inclination. The reeling rails 10
are attached pivotally to the reeling cylinder 15,
and the reeling rails 10 are preferably mounted to
the center point of the reeling cylinder 15.
As shown in FIG. 4, additional forces F may be
applied to the ends of the reeling drum 20 in a
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direction perpendicular to the axial direction of the
roll by means of suitable members 35, e.g. means for
supporting and shifting the reeling drum, in which
case it is possible to control and regulate the nip
pressure in the transverse direction of the machine,
i.e. in the axial direction of the reeling drum 20.
The members 35 are also referred to as "members for
the application of additional forces." If it is
desirable to act upon the transverse profile of nip
load by applying the additional forces F, while at
the same time keeping the overall nip load unchanged,
the angle a of inclination can be adjusted so as to
compensate for the effect of the additional forces F
on the overall nip load.
The nip load in the transverse direction of the
machine, i.e. in the axial direction of the reeling
drum 20, is regulated in the middle by changing the
relative positions of the reeling cylinder 15 and the
reeling drum 20, e.g. by altering the angle a of
inclination of the rails 10. When the angle a of
inclination is increased, the nip load is increased
in the middle, and when the angle a of inclination is
reduced, the nip load is reduced in the middle. By
application of the additional forces F, the nip load
is increased or reduced in the lateral areas. Thus,
the overall nip load can be regulated in the desired
way.
As shown in FIG. 5, the arrangement of the
invention is suitable for use when the reeling is
continuous. In FIG. 5, a construction is shown in
which two systems of reeling cylinders 15 and rails
10 are employed. In FIG. 5, the web W guide rolls
are denoted with the reference numeral 25. As is
shown in the figure, as the jumbo roll 20 becomes
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larger, the angle a is reduced. When one jumbo roll
20 is complete, the web W is passed to the other
reeling system, which operates in a similar way.
FIG. 6 illustrates a system in which continuous
reeling is possible. The web W is passed over the
guide rolls 25 onto the reeling cylinder 15, and from
there further onto one of the reeling drums 20
supported on one set of rails 10. Upon completion of
the reeling onto one reeling drum, the web W is
guided to the other reeling drum. In FIG. 6, the
dashed lines indicate the positions of the rails 10
and the reeling drums 20 when the jumbo rolls are
complete.
As shown in FIG. 7, for example, in a Pope-type
reel-up, the exchange of the reeling drum from the
primary rails 10 onto the secondary rails 11 is
carried out by means of the primary rails 10 while
the full jumbo roll 20 revolves on the secondary
rails 11. The full jumbo roll 21 is shifted to the
braking position, whereupon the primary rails 10 can
be shifted to a position that is optimal in view of
the desired nip load for the new roll and the new
reeling drum is loaded onto the primary rails. The
nip pressure Gr is uniform in the transverse
direction and the overall nip load Gr is equal to G
sin a. The full jumbo roll 21 is removed from the
secondary rails. As the new jumbo roll 20 becomes
larger, the angle a is reduced. The jumbo roll 20 is
shifted onto the secondary rails 11 by positioning
the secondary rails 11 at the same angle a as the
primary rails so that the reeling drum is able to
roll over the joint onto the secondary rails as
reeling progresses. During the shifting, the primary
rails 10 and the secondary rails 11 are moved
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synchronously when the nip load is adjusted. The
secondary rails 11 may also be fixed stationarily, in
which case the regulation of the nip load takes place
on said rails in the normal manner by use of reeling
forks .
Above, the invention has been described with
reference to some of its preferred embodiments only.
This is, however, by no means supposed to confine the
invention to these exemplifying embodiments only, but
many variations and modifications are possible within
the scope of the invention defined in the following
patent claims.
