[0001] The present invention relates to a two-drum winder for winding partial webs according
to the preamble of claim 1 for reducing machine directional vibrations in a partial
web winder of a fibrous web. Invention relates also to method of operating a two-drum
winder according to preamble of the other independent claim.
[0002] As is known in prior art, in a slitter-winder the machine roll is un-wound and the
wide web is slit with the slitting part of the slitter-winder into a number of narrower
partial webs that are rewound with a partial web winder to form customer rolls. When
the customer rolls being simultaneously made from each partial web are ready, the
slitter-winder is stopped and the partial web rolls are removed from the machine,
i.e. the set change is done. Subsequent to this the process is continued as winding
of a new set of rolls. These phases are repeated in sequences until the machine roll
runs out of paper, whereby the machine roll is changed and the operation is started
again as unwinding another machine roll. The partial web winder can be a two-drum
type winder in which the partial web rolls are wound carried by winding drums, typically
supported by a rider roll from above.
[0003] In winding, e.g. when winding a paper web with a slitter-winder, large vibrations
occur in certain paper types at same roll rotation frequency ranges regardless of
the running speed of the slitter. Usually there are about 1 to 3 vibration ranges,
i.e. rotation speed ranges of the roll on which there is strong vibration, depending
on the final diameter of the roll. This strong vibration causes winding reject, mechanical
wear of the apparatuses, even loosening of the roll from the winding apparatus as
well as decrease of winding capacity as the running speed has to be lowered during
winding.
[0004] FI101283 discloses a method in which the running speed of the winder is controlled based on
the rotation frequency of the roll so that as the rotation frequency of the roll approaches
the vicinity of the vibration range, i.e. the roll rotation frequency range where
there is a strong vibration, the running speed is quickly lowered so that the rotation
speed of the roll decreases to below the lower frequency of the vibration range and
subsequent to this the running speed is increased so that the rotation frequency of
the roll remains constant until the original running speed of the winder is reached.
Due to the change of the running speed this has an effect on the total capacity of
the winder.
[0005] As the size of the partial web rolls increases during the winding, at least the rider
roll is moved to compensate the growth of the diameter of the rolls. Thus at least
the rider roll arrangement is movably supported by the body structure of the winding
part. The consecutive longitudinal rolls are locked in their places as a line of rolls
by means of a core locking device arranged at both ends. The support means contacting
the roll (or rolls) to be wound are exposed to the dynamic load caused by the rotating
roll. Especially in connection with two-drum type of winders there occur dynamic loads
causing vibration especially in the rider roll and the supporting rider roll beam,
excited by the partial web rolls to be wound. It is also typical for the process that
the diameter of the roll to be wound has an effect on the vibration of the rider roll.
Thus the vibration conditions change as the winding proceeds.
[0006] The design aim of the rider roll of a slitter-winder is a stable construction able
to withstand dynamic load. A generally used practical solution is one in which rider
roll segments are suspended from a relatively rigid rider roll beam. The rider roll
beam is moved along two or more guides attached to the body. Both the guides and the
cylinders are located near the ends of the beam.
[0007] A particular form of vibration occurring in a two-drum winder is machine directional
concurrent vibration of the rolls in the set. In a slitter-winder of the two-drum
type, the whole set or single rolls can start to oscillate typically on a relatively
low frequency (about 5 -15 Hz) in the machine direction on top of the winding drums.
The phenomenon can limit the maximum speed usable in winding, thus decreasing capacity.
In the worst case, the phenomenon can cause the off-throwing of the set.
[0008] Specification
US 4180216 presents as a solution for the problem transferring the rider roll during winding
along the surface of the web roll from its peak point as the web roll increases with
the purpose of changing the spring constant of the web roll being completed. The specification
also suggests using several rider rolls simultaneously to support the set. The adjustment
of the position of the rider roll is described occurring pre-programmedly based on
experience and the roll diameter of the set being completed, among others. With this
type of an arrangement, it is in practice not possible to prevent the phenomenon sufficiently,
because actual conditions in winding are always different from the ones of a previously
compiled statistical model.
[0009] With certain fibrous-web types, the forming of partial web rolls can be achieved
more advantageous if the rider roll is provided with a drive. Then, it is possible
to apply moment/force, i.e. pull, to the surface of the web roll with the rider roll.
Publication
EP2108606 A2 describes a two-drum winder in which the rider roll unit comprises a drive. More
particularly there is disclosed a two-drum winder which comprises at least two surface
support elements of the roll arranged to support at least one roll being formed substantially
below it and at least one loading device which is arranged to support said roll at
least for part of the forming time of the roll substantially above it. The winder
comprises also at least one drive so that the drive is arranged to apply tangential
force to the roll being wound and a control arrangement which is arranged to control
said at least one drive of the two-drum winder so that the drive provides the roll
being wound with an effect diminishing the machine directional concurrent vibration
of parallel rolls, which in this case is machine directional concurrent vibration
of the rolls in the current set.. In order to operate in acceptable manner the drive
must be of considerable power and the system requires somewhat sophisticated controlling
system.
[0010] Object of the invention is to provide such a two-drum winder by means of which the
machine directional concurrent vibration of the rolls is at least minimized in a straightforward
manner.
[0011] The objects of the invention are mainly achieved with a two-drum winder for winding
partial webs according to claim 1 and method of operating a two-drum winder according
to claim 11.
[0012] Unless more particularly defined, in this context the following definitions are valid.
A two-drum winder refers to a web winder in which at least one roll being formed is
supported below the roll with at least two surface support devices of the winder,
such as a roll or a set of belts supported by rolls. The cross direction refers to
the direction of the longitudinal axis of the surface support device, such as the
roll, and the machine direction the direction perpendicular in relation to the cross
direction and the vertical direction. A set refers to a set of partial web rolls being
wound simultaneously on the winder. A roll refers to one or more rolls. Above and
below refer to the upper side and under side of a horizontal plane passing via the
centre of the roll. Belt means a belt, chain or any other endless power transmission
Ioop.Term rigid means rigid in practical sense without an intention of having flexibility
and/or rigid element does not influence on the dynamics of the rotation of the system.
[0013] Object of the invention are met by a two-drum winder for winding partial webs for
a fibrous web comprising at least two surface support elements to support a web roll
from below and a rider roll which is arranged to support said web roll at least for
part of the forming time of the web roll above it. The rider roll is provided with
a vibration damper arranged to attenuate rotational vibration of the rider roll such
that the machine directional concurrent vibration of the web roll is attenuated via
tangential force interaction between the rider roll and the web roll, and the vibration
damper comprises a mass element which is rigidly coupled by a coupling system to the
rider roll to rotate along with the rider roll.
[0014] Since the mass element is not in connection with, or in other words, is separated
from the web rolls it size may be selected with greater freedom and based on the demands
of its primary function.
[0015] Thus whenever the set of web rolls is subjected to the machine directional concurrent
vibration excitation and would otherwise begin to resonate, the vibration damperreduces
the machine directional vibrations of the web rolls. By selecting the mass moment
of inertia properly it is also possible to affect the frequency of the resonance frequency.
[0016] According to an embodiment of the invention the coupling system comprises power transmission
coupling between the rider roll and the mass element.
[0017] According to an embodiment of the invention the coupling system comprises power transmission
coupling between the rider roll and the mass element which is provided with on/off
coupling so that the mass element may be engaged to or disengaged from the rider roll.
So, as the rotation frequency of the rolls approaches the vicinity of the vibration
range, i.e. the roll rotation frequency range where there is a strong vibration, the
mass element may be coupled (or uncoupled in case it was previously coupled) to the
rider roll. Due to effect of the mass element the resonance frequency may be change
away from the rotation frequency of the rolls.
[0018] According to an embodiment of the invention the coupling system comprises power transmission
loop coupling, having a first wheel connected to the rider roll and a second wheel
connected to the mass element and a power transmission loop connecting the first and
the second wheels.
[0019] According to an embodiment of the invention the first and the second wheel provide
a gear ratio different from 1:1. Preferably the gear ratio is such that the mass element
of the vibration damper is arranged to rotate at greater angular speed than the rider
roll.
[0020] According to an embodiment of the invention the rider roll is supported by a beam
extending over the length of the rider roll and comprising end walls at the opposite
end thereof and the that the vibration damper is rotatably supported to the end walls.
[0021] According to an embodiment of the invention the rider roll is supported by a beam
extending over the length of the rider roll and that the vibration damper is rotatably
supported inside the beam.
[0022] According to an embodiment of the invention the vibration damper is arranged adjustable
during operation of the two-drum winder.
[0023] According to an embodiment of the invention the coupling system comprises power transmission
having a variably controllable transmission.
[0024] According to an embodiment of the invention the vibration damper comprises a friction
damper coupled by a coupling system to the rider roll to rotate along with the rider
roll.
[0025] According to an embodiment of the invention the vibration damper comprises a friction
damper comprises a clutch member connected to the coupling system and a mass unit
which is arranged rotatable such that the rotation is suppressed or allowed by a friction
force in the contact between the mass unit and the clutch member.
[0026] A particular embodiment of the invention relates to initial acceleration phase of
the winding during which the frequency of excitation of the machine directional concurrent
vibration of the web roll is considerably high. The initial phase forms the bottom
of the roll over which the layers are formed and therefore it is an important phase.
In order to adequately suppress theconcurrent vibration of the web roll the overall
moment of inertia of the mass element of the vibration damper is at least 1,5 times
the moment of inertia of the rider roll, but at least 5 m/s
2.
[0027] An object of the invention is also met by a method in which a two-drum winder is
operated for winding partial webs for a fibrous web on at least two surface support
elements to support a web roll from below and a rider roll which supports said web
roll at least for part of the forming time of the web roll above it. The rider roll
is provided with a vibration damper arranged to attenuate rotational vibration of
the rider roll such that the machine directional concurrent vibration of the web roll
is attenuated via tangential force interaction between the rider roll and the web
roll, in which rotational vibration of the rider roll is damped by the vibration damper
comprising a mass element which is rigidly coupled by a coupling system to the rider
roll to rotate along with the rider roll.
[0028] According to an embodiment of the invention the method the mass moment of the inertia
of the mass element is arranged to change the resonance frequency of the vibration.
[0029] According to another embodiment of the invention the winder is operated so that as
the rotation frequency of the rolls approaches the vicinity of the vibration range
the mass element is be coupled or uncoupled in case it was previously coupled, to
the rider roll.
[0030] Due to effect of the mass element the resonance frequency may be change away from
the rotation frequency of the rolls.
[0031] The other additional characteristic features of the invention will become apparent
from the appended claims and the following description of the embodiments of figures.
[0032] In the following the invention and its operation are described with reference to
the appended schematic drawings, in which
figure 1 illustrates an embodiment according to the invention in connection with a
partial web winder of the two-drum type,
figure 2 illustrates a sectional view in the direction A of the figure 1, and
figure 3 illustrates an embodiment according to the invention in connection with a
rider roll and rider roll beam,
figure 4 illustrates another embodiment according to the invention in connection with
a rider roll and rider roll beam,
figure 5 illustrates still another embodiment according to the invention in connection
with a rider roll and rider roll beam,
figure 6 illustrates still another embodiment according to the invention in connection
with a rider roll and rider roll beam,
figure 7 illustrates still another embodiment according to the invention in connection
with a rider roll and rider roll beam, and
figure8 illustrates an example of operation of an embodiment of the invention.
[0033] Fig. 1 shows a two-drum winder 10 according to an embodiment of the invention. The
two-drum winder comprises a front winding drum 15 and a rear winding drum 20 as support
rolls. The winding drums supportfrom below a set ofweb rolls 25 being wound of partial
webs W in the winder in a manner known as such. To support the roll 25 from the abovethere
is also arranged a rider roll 30. The rider roll 30 is supported on a rider-roll beam
35. Here the terms above and below refer to the upside and underside of a horizontal
plane passing via the centre of the roll. The rider roll may be a single roll extending
from the first (front) side of the winder to the second (back) side thereof or it
may be constructed of several interconnected roll segments. The interconnection means
that the roll segments are rotatable connected with each other.
[0034] The winding drums 15, 20 of the two-drum winder 10 are provided with drives 15.1,
20.1 by means of which surface draw i.e. tangential force can be applied to the roll
being formed. The rider roll 30 may also be provided with a drive, even if not shown
here.
[0035] Fig. 1 schematically shows the machine directional concurrent vibration of parallel
rolls which can be at least considerably minimised or even eliminated with the two-drum
winder. In the machine directional concurrent vibration of parallel rolls 25, the
whole set reference 25' in Fig. 2, moves back and forth in the machine direction from
its stable position mainly by rotating alternately on the surface of the front and
rear drum 15, 20 as is shown in exaggerated manner in Fig. 1.Individual back and forth
motion of single rolls can be minimized by combining successive rolls 25 of the set
25' from their winding centers to each other e.g. by a sleeve 45 which sufficiently
locks the centers to each other radially. This can be seen in Fig. 2, which shows
section of the two-drum winder of Fig. 1 from direction A.
[0036] When examining the machine directional concurrent vibration of parallel rolls shown
by Fig. 1 by way of an example in more detail, it is found that the web rollwill rotate
around the winding drum 15 cloc ise, motion d1. Then, when rotating, each web roll
is pressed with greater force against the rider roll 30. Equivalently, the set will
rotate around the winding drum 20 counter clockwise, motion d2. Also from the effect
of this motion d2, the web rolls are pressed with greater force against the rider
roll 30. Then, nip force momentarily risen on the rider roll also increases friction
force between the rider roll 30 and the surface of the web roll 25. The increase of
friction force thus occurs at such points of time when via the rider roll 30 the effect
of the vibration damper is to be conveyed to the web rolls of the set 25'. Hence,
the arrangement according to the invention is very advantageous.
[0037] According to the invention the rider roll 30 is provided with a vibration damper
40, which comprises a mass element 42providing additional massto even the machine
directional concurrent vibration of the web roll 25. The mass element 42 is rigidly
coupled by a coupling system 44 to the rider roll 30. It is arranged to rotate along
with the rider roll. Thus, the in case the machine directional concurrent vibration
of the web roll 25 tends to take place, the excitation of the vibration is transmitted
into rotational oscillation of the rider roll 30. Due to the increased inertia of
the rider roll - vibration damper system the rotational oscillation of the rider roll
30 is reduced and thus the machine directional concurrent vibration of the web roll
25 is minimized accordingly.
[0038] The machine directional concurrent vibration of parallel rolls affecting the whole
set 25' can be minimised when the two-drum winder 10 comprises a vibration damper
40 arranged to the rider roll 30. The vibration damper 40 comprises a mass element
42 of suitable form. The mass element is coupled to the rider roll 30 by a coupling
system 44 so that the mass element may rotate along with the rider roll by means of
which the inertia of the system is increased. The mass element 42 coupled to the roll
30 via the coupling system is rigidso that the mass element follows the rotational
vibration of the rider roll 30.
[0039] In the embodiment of figure 1 and 2 the coupling system is a bar or a shaftarranged
at the common rotational axis of the roll and the mass element 42. The mass element
is coupled to an end of the roll 30.
[0040] In figure 3 there is shown the rider roll and the beam according to an embodiment
of the invention in which the vibration damper 40 is arranged above the beam 35 of
the winder. This way it does not require or reserve space on the side of the winder,
which is advantageous.The vibration damper 40 being located at a distance from the
rider roll needs a coupling system which facilitates power transmission between the
roll and the mass element 42. Thus the coupling system comprises a belt drive coupling
50 having a first belt wheel 51 connected to the rider roll 30 and a second belt wheel
52 connected to the mass element 42 and a belt 53 connecting the first and the second
belt wheels. The belt is still or inelastic so that the mass element follows the rotation
and rotational vibration of the rider roll 30.
[0041] In figure 4 there is shown an embodiment of the invention in which the vibration
damper 40 is arranged inside the rider roll beam 35 of the winder. In figure 4 there
is also shown how the coupling system50 comprises a power transmission coupling between
the rider roll and the mass element. Particularly in the figure 4 the power transmission
coupling is abelt drive coupling 50. The belt drive coupling comprising a first belt
wheel 51 connected to the rider roll 30 and a second belt wheel 52 connected to the
mass element 42 and a belt 53 connecting the first and the second belt wheels. The
mass element 42 is supported to an end walls 35' of the beam 35.As can be seen the
mass element is in the figure 4 a cylindrical object. What is noteworthy is that the
first belt wheel and the second belt wheel are of different effective diameter, in
other words the first and the second wheel provide a gear ratio different from 1:1.
It is particularly advantageous when the mass element is arranged to rotate at higher
speed than the rider roll. Increasing the rotational speed of the mass element the
kinetic energy may be increased without increasing the moment of inertia of the mass
element of the vibration damper.
[0042] The gear ratio should in practice be as big as possible given that the flexibility
of the transmission, e.g. a belt will not disturb or dominate the operation. The mass
moment of inertia increases with square of the gear ratio.
[0043] Thus according to an embodiment of the invention the rotational speed of the mass
element is arranged to increase in response to the web roll diameter.
[0044] As an example, if the mass has a certain weight (or moment of inertia), its effect
to the kinetic energy of the rotating mass element may be increased by square by increasing
its rotational speed. Thus the rider roll may prevent more efficiently the machine
directional concurrent vibration of the web roll via tangential force interaction
between the rider roll 30 and set 25' of the web rolls 25.
[0045] Even if not shown, the power transmission coupling may be realized also by different
kinds of gear or surface drive devices.The weight of the mass element may be of the
same magnitude as the rider roll.
[0046] In figure 5 there is shown an embodiment of the invention in which the vibration
damper 40 is also arranged inside the rider roll beam 35 of the winder. The coupling
system44 comprises a belt drive coupling 50 as the power transmission system. The
belt drive coupling comprises a first belt wheel 51 connected to the rider roll 30.
The first belt wheel is nonadjustable i.e. its diameter is fixed. The second belt
wheel 52 connected to drive the mass element 42 is adjustable such that its effective
diameter may be changed during the operation and thus the transmission ratio of the
belt drive coupling may be changed. The second wheel may comprise means for changing
the distance between the opposing inner surfaces of the wheel which, given that the
belt has fixed width, changes the radial contact distance of the belt. A belt 53 is
connecting the first and the second belt wheels.
[0047] In figure 6 there is shown an embodiment of the invention in which the mass element
of the vibration damper comprises a friction damper 60. The friction damper may be
attached in connection with a separate mass element 42, as is the case in figure 6.The
friction damper may also be constructed to be in integral part of the mass element
or it may be the mass element by selecting its the weight properly.
[0048] The friction damper 60 is shown enlarged as its encircled portion in the figure.
The friction damper 60 comprises a shaft 62 which is coupled to the mass element or
to the second belt wheel 52 or the coupling system 44 (not shown). Thus the shaft
62 rotates along with the coupling system and thus also with the rider roll 30. The
friction damper comprises a clutch member 64 secured to the shaft 62 so that they
rotate as a unit. The purpose and operation of the clutch member will be explained
later. The friction damper 60 comprises further a mass unit 66 which supported rotatably
in respect to the shaft. In the figure 7 the mass unit 66 supported by bearings 68
to the clutch member 64. Alternatively the mass unit 66 may be supported directly
by the shaft 62.
[0049] The mass unit 66 is constantly pressed against the clutch member 64 so that friction
force in the contact between the mass unit 66 and the clutch member 64 maintains the
otherwise freely rotatable mass unit 66 fixed with the clutch member.
[0050] In the embodiment of figure 6 the mass unit 66 comprises two disk-like parts 66.1,
66.2 and the clutch member 64 comprises a portion 70 radially between the two disk-like
parts 66.1, 66.2. The disk-like parts are urged towards each other by spring elements
72 pressed by pins 74 or a like so that the clutch member 64 is constantly pressed
between them. The press contact is made via friction pads 74.The mass unit 66 and
the clutch member 63 are immovably coupled with each other until the clutch member
accelerates so strongly that the force exceeds the static friction. On other words,
it is only after the torque between the mass unit 66 and the clutch member 64 brings
about a force to the joint between the mass unit 66 and the clutch member 64 exceeding
the static friction of the joint, the mass unit 66 will rotated at lower speed than
the clutch member 64 and dynamic friction of the joint dissipates as heat to the surroundings.
This of solution is shown in generally in publication
W. T. Thomson 1972, Theory of Vibration. New Jersey: Prentice-Hall.
[0051] In case the friction damper is constructed to be the mass element the total weight
of the friction damper is allocated between the mass unit 66 and the clutch member
64 to the case. An example of such construction is shown in figure 7 using the same
reference number for corresponding elements.
[0052] In the figure 8 there is shown the effect of the invention as an example. The graph
70 depicts the case without the vibration damper, the graph 72 depicts the case with
4 times increased mass moment of inertia of the rider rolls, the graph 74 depicts
the case with 8 times increased mass moment of inertia of the rider rolls and the
graph 76 depicts the case with 12 times increased mass moment of inertia of the rider
rolls. The characteristics of the winder were: width of the set 7 m, diameter of the
web rolls 900 mm, the mass eccentricity of the web rolls 0.01 mm, diameter of the
winding drums 800 mm, diameter of the rider rolls 200 mm. From the figure 8 it can
be seen that the increase of the mass moment of inertia has two effects: the height
of the resonance spike decreases with the mass moment of inertia and secondly the
natural frequency decrease with the mass moment of inertia. The former feature enables
avoiding running at the resonance by altering the mass moment of inertia according
to the rotation frequency of the web rolls.
[0053] It should be noted that only a few of the most preferable embodiments are disclosed
above. Thus, it is obvious that the invention is not limited to the above-mentioned
embodiments but it can be applied in many ways within the scope defined by the appended
claims. The features disclosed in connection with various embodiments can also be
used in connection with other embodiments within the inventive scope and/or different
embodiments can be combined from the disclosed features, should it be desired and
should it be technically feasible.
1. A two-drum winder for winding partial webs (10) for a fibrous web comprising at least
two surface support elements (15, 20) to support a web roll (25) from below and a
rider roll (30) which is arranged to support said web roll (25) at least for part
of the forming time of the web roll above it, characterized in that the rider roll (30) is provided with a vibration damper (40) arranged to attenuate
rotational vibration of the rider roll such that the machine directional concurrent
vibration of the web roll is attenuated via tangential force interaction between the
rider roll (30) and the web roll (25), and that the vibration damper(40) comprises
a mass element (42) which is rigidly coupled by a coupling system to the rider roll
(30) to rotate along with the rider roll.
2. A two-drum winder for winding partial webs (10) according to claim 1, characterized in that coupling system (44) comprises power transmission coupling between the rider roll
(30) and the mass element (42).
3. A two-drum winder for winding partial webs (10) according to claim 2, characterized in that coupling system (44) is provided with on/off coupling.
3. A two-drum winder for winding partial webs (10) according to claim 2, characterized in that coupling system comprises power transmission loop coupling, having a first wheel
connected to the rider roll and a second wheel connected to the mass element and a
power transmission loop connecting the first and the second wheels.
4. A two-drum winder for winding partial webs (10) according to claim 2, characterized in that the first and the second wheel provide a gear ratio different from 1:1.
5. A two-drum winder for winding partial webs (10) according to claim 1, characterized in that the rider roll (30) is supported by a beam (35) extending over the length of the
rider roll (30) and comprising end walls (35') at the opposite end thereof and the
that the vibration damper is rotatably supported to the end walls.
6. A two-drum winder for winding partial webs (10) according to claim 1, characterized in that the rider roll (30) is supported by a beam (35) extending over the length of the
rider roll (30) and that the vibration damper (40) is rotatably supported inside the
beam (35).
7. A two-drum winder for winding partial webs (10) according to claim 2, characterized in that the vibration damper is arranged adjustable during operation of the two-drum winder
(10).
8. A two-drum winder for winding partial webs (10) according to claim 2 or 6, characterized in that coupling system comprises power transmission having a variably controllable transmission.
9. A two-drum winder for winding partial webs (10) according to claim 1, characterized in that vibration damper comprises a friction damper coupled by a coupling system to the
rider roll (30) to rotate along with the rider roll.
10. A two-drum winder for winding partial webs (10) according to claim 9, characterized in that vibration damper comprises a friction damper comprises a clutch member (64) connected
to the coupling system and a mass unit (66) which is arranged rotatable such that
the rotation is suppressed or allowed by a friction force in the contact between the
mass unit (66) and the clutch member (64).
11. Method of operating a two-drum winder in which partial webs (10) for a fibrous web
are wound on at least two surface support elements (15,20) supporting a web roll (25)
from below and in which a rider roll (30) supports said web roll at least for part
of the forming time of the web roll above it, characterized in that the rider roll (30) is provided with a vibration damper (40) arranged to attenuate
rotational vibration of the rider roll such that the machine directional concurrent
vibration of the web roll (25) is attenuated via tangential force interaction between
the rider roll and the web roll, in which rotational vibration of the rider roll is
damped by the vibration damper (40) comprising a mass element (42) which is rigidly
coupled by a coupling system to the rider roll to rotate along with the rider roll.
12. Method according to claim 11, characterized in that in the method the mass moment of the inertia of the mass element (42) is arranged
to change the resonance frequency of the vibration.
13. Method according to claim 12, characterized in that the winder is operated so that as the rotation frequency of the rolls approaches
the vicinity of the vibration range the mass element is be coupled or uncoupled in
case it was previously coupled, to the rider roll.