FI127824B - Mass damper and arrangement in a fibre web machine - Google Patents

Abstract

The invention relates to a mass damper (10) for a deflection compensated roll (12) forming a nip (102) of a fiber web machine, comprising a mass absorber (10) for mounting a mass damper (10) to a deflection compensated roll (16) in, - a resilient element (18) attached to the frame (14), said resilient element (18) being a guide shaft (20) comprising a resilient area (30), the outside of the resilient area (30) being fixed to the frame (14) , - a mass body (22) arranged in connection with said resilient element (18) in a flexible region (30) - displacement means (24) for moving the mass body (22) along the guide shaft (20) and - locking means (26) for locking the mass body (22) (14) by means of a guide shaft (20). The invention also relates to an arrangement in a fiber web machine.

Description

WEIGHT DAMPER AND ARRANGEMENT IN FIBER MACHINE

The present invention relates to a mass suppressor for a deflection compensated roll forming a nip in a fiber web machine,

- a body for attaching a mass damper to a stationary axis of a deflection roll within the deflection roll,

- a flexible element attached to the frame,

- a mass body fitted to said elastic member.

The invention also relates to an arrangement in a fiber web machine.

In a fiber web machine, the fiber web is guided to a nip forming between the two rolls 15, from which the fiber web passes under pressure by the rolls to compact the fiber web. The unevenness of the fibrous web entering the nip causes harmful vibrations to the nip rolls, which in turn cause thickness differences in the finished product. In addition, roller rollers cause the roller coating to deform unevenly, shortening roll maintenance intervals.

To eliminate vibrations, there are mass dampers where

20185055 prh 22 -01- 2018 The mass of the damper is attached to the roll by a spring.

The mass constant of the spring of the spring and the selection or adjustment of the damper mass of the roller.

and the mass of the mass body provides a state of oscillation

In this case, at the same mass frequency of the roll as the oscillation moves, the vibration of the mass roll is damped or stopped.

In a plurality of nipples, the at least one roll is a deflection compensated roll including a stationary shaft for attaching a deflection compensated roll to a fiber web machine, a rotatable sheath supported by a stationary shaft by means of bearings and means for compensating the deflection of the sheath. Prior art FI 119519 B discloses such a mass absorber for a deflection compensated roll. In the case of the deflection compensated roll of this publication, the mass damper is attached to the stationary axis of the deflection compensated roll inside the roll casing so that the mass absorber is positioned at a point of greatest amplitude in terms of roll vibration.

The mass absorber is preferably not attached to the support of the deflection compensated roll and the fiber web machine because at the point of support the vibration amplitude is very small and the mass absorber does not provide sufficient damping power to attenuate the roll vibrations at the center of the roll.

The mass suppressor of FI 119519 B includes a two-piece body for attaching a mass damper to a stationary shaft of a deflection roll, within the deflection roll, and resilient elements fitted between the portions of the body and fixed to the body. However, the problem with such a mass absorber 20 is its complex construction, which is difficult to manufacture. Another problem is the poor damping capacity of such a mass suppressor.

20185055 prh 22 -01- 2018

It is an object of the invention to provide a mass suppressor which is easier to manufacture than prior art mass 25, which achieves greater damping efficiency. It is also an object of the invention to provide an arrangement 30 having better damping efficiency in a fiber web machine than prior art arrangements. Characteristic features of this invention are apparent from the appended claim 13.

The object of the invention may be achieved by a mass damper for a deflection compensated roll forming a nip of a fiber web machine, which includes a body for attaching a mass absorber to a stationary shaft of a deflection compensated roll within a deflection compensated roll and a flexible element. The resilient element is a guide shaft which includes a resilient area. The guide shaft is secured to the frame from the outside of the elastic region, and the mass body is fitted within the elastic region. The mass suppressor further comprises moving means for moving the mass body lengthwise along the guide shaft and locking means for locking the mass body spaced from the body by the guide shaft.

20185055 prh 22 -01- 2018

In the mass suppressor according to the invention, the guide shaft is supported on the frame from outside the elastic region and through the housing 15 to the stationary axis of the deflected roller, whereby the guide shaft is more freely flexible in the elastic region. The free elasticity of the elastic region and the mass body placed therein, and thus the greater amplitude of the oscillation, allow for better damping capacity. In other words, in the mass 20 damper according to the invention, at least one of the ends of the guide shaft is unsupported and free from vibration.

According to one embodiment, the guide shaft is fixedly attached to the body and the pulp body is arranged to be moved around the guide shaft 25 in a flexible region, with locking means being fitted to the pulp body and transferring means being arranged to move the pulp body along the guide shaft. In such an embodiment, the structure of the body can be quite simple.

According to another embodiment, the guide shaft is movably secured to the frame and the pulp body is fixedly attached to the guide shaft, with locking means fitted to the frame and transfer means being provided

20185055 prh 22 -01-2018 to move the guide shaft longitudinally relative to the frame. Such a solution can be challenging due to the torque forces at the point of attachment between the frame and the guide shaft.

In both of the above embodiments, precise and stepless sliding displacement are best suited for adjusting the distance between the mass body and the body, wherein the guide shaft and the counter surfaces (mass or body) are smooth (preferably at least in one part flat or beveled).

In other words, in the mass suppressor according to the invention, the mass body is supported by only one guide shaft. This 15 simplifies the structure of the mass suppressor. The guide shaft may also be referred to as a cantilever beam.

Preferably, the guide shaft is supported only at one point in the body. In this case, any deformation 20 of the stationary shaft cannot enter the elastic region of the guide shaft, because the guide shaft is supported only at one point, leaving at least one of the ends of the guide shaft unsupported and free from vibration.

The elastic region in the elastic member may extend from the first end towards the second end over a length of 40 to 80%, preferably 60 to 70% of the total length of the elastic member. Thus, the elastic region is long enough to obtain a sufficiently large vibration amplitude of the mass body and the characteristic frequency of the vibration of the mass body is adjustable over a sufficiently wide frequency range.

According to one embodiment, the guide shaft includes bevels or reliefs on both sides of the guide shaft to direct damping and prevent rotation of the mass body. By means of bevels in the direction of the nip, the stiffness of the guide shaft can be adjusted, whereby the vibration of the guide shaft takes place mainly in the desired direction, preferably in the direction of the nip.

Preferably, the aperture inserted into the pulp body does not correspond to the cross-section of the guide shaft, whereby by means of bevels and wedges the rotation of the pulp body on the guide shaft is prevented.

According to one embodiment, the locking means include a locking member 15 for clamping the mass member against the guide shaft, a spring-loaded locking actuator for locking the mass member and a release actuator for pushing the locking member locking member to release external force by reversing the force exerted by the locking actuator.

With such locking means, the mass body remains locked in the longitudinal direction of the guide shaft, even if no external force is applied to the mass absorber, for example, in the event of a malfunction. this is

20185055 prh 22 -01-2018 safety feature that prevents uncontrolled movement of the mass body 20 along the guide axis in longitudinal and transverse direction in a situation where no external force to lock the body is available. Unlocking the spring-loaded locking actuator by external force stores energy in the spring, which is later available for locking the locking means without external force.

Preferably, the locking members include a bevelled surface for converting a substantially parallel force of the locking actuator into a transverse direction of the guide shaft. In this way the locking means 30 can be implemented in a small space.

The locking members may be partially split bushes. Split sleeves require less force to provide the required locking than single sleeves and have greater tolerance to the sleeve sleeves when fitted. In sleeve locking, the locking and release force acts directly on the sleeve, reducing the amount of locking required. In this case, hydraulic cylinder means are not needed since the sleeve 5 also functions as a piston.

Preferably, the transfer means is a hydraulic cylinder comprising a cylinder member and a piston rod. The hydraulic cylinder is reliable and inexpensive to implement.

Preferably, the piston rod of the hydraulic cylinder is longitudinally disposed through the guide shaft and the cylinder member is secured to the body on the opposite side of the body relative to the guide shaft. Thus, the force exerted by the transfer means on the pulp body is centrally relative to the guide shaft and does not tend to rotate the pulp body.

The guide shaft may be supported on the frame by a support length of 10

- 40%, preferably 15-25% of the length of the guide shaft. In this case, the guide shaft 20 has a sufficiently long elastic area, but on the other hand, the guide shaft can be fixedly supported on the frame and thereby on the body of the deflection compensated roll.

20185055 prh 22 -01- 2018

The guide shaft can

-400 mm, to be supported on the frame at a support length, preferably

0 - 2 5 0 mm.

which is 100

Such a length of support is suitable for the benefit outlined above

The mass of butter may be 10 0

300 mm, to achieve.

be supported on the guide shaft at a support length of preferably 100 µs

200 mm. Thus, the support length of the pulp body is short, whereby the free elastic region between the pulp body and the body over a longer distance to the elastic.

20185055 prh 22 -01- 2018

In other words, in a mass absorber, the guide shaft comprises two ends, at least one of which is free to oscillate with the mass member.

Another object of the invention may be achieved by an arrangement in a fiber web machine comprising two rolls forming a nip between them, one roll being a deflection compensated roll comprising a stationary axis for supporting the roll on a fiber web machine; to dampen roll vibrations. By the arrangement of the invention, the vibrations of the deflection compensated roll can be effectively eliminated, extending the roll life and improving the homogeneity of the fibrous web being manufactured.

Preferably, the arrangement includes two mass dampers fitted inside the deflection compensated roll to achieve greater damping capacity. Since the damping capacity of the mass absorber is partly determined by the ratio between the mass of the mass body and the mass of the roll, the greater combined mass of the two mass absorbers enables a better damping capacity without increasing the external dimensions of the individual mass absorber.

The placement of the mass absorber within the shell of the deflection compensated roll greatly limits the outer dimensions of the mass absorber and thereby the mass of the mass body.

In calendars, the deflection-compensated roll preferably comprises 30 soft surface structures. In particular, deflection compensated rolls having a soft surface structure are susceptible to vibrations when the irregularity of the fibrous web causes excitation of the soft surface structure and thereby of the roll. In addition, deflection compensated rollers with a soft surface structure are subject to uneven wear of the soft surface structure of the roll due to vibration, which requires the coating to be sanded or renewed.

The stiffness of the guide shaft of the mass suppressor may be different in the direction of the nip and perpendicular thereto to direct the damping in the desired direction, preferably parallel to the nip. In this way, the harmful vibrations of the deflection-compensated roll in the direction of the nip can be more effectively attenuated when the vibration of the mass body is parallel. Here, the nip direction refers to 10 directions perpendicular to the contact surface between the rolls and transverse to the rolls.

Specifically, the mass damper according to the invention is characterized in that the resilient element is a guide shaft having a resilient region. The guide shaft is secured to the frame from the outside of the elastic region and the mass body is fitted into the elastic region. The mass suppressor further comprises moving means for moving the mass body longitudinally of the guide shaft and locking means for locking the body of mass 20 spaced from the body by the guide shaft.

20185055 prh 22 -01- 2018

More specifically, the arrangement according to the invention is characterized in that the mass suppressor of the arrangement is a mass suppressor according to an embodiment.

The invention will now be described in detail with reference to the accompanying drawings, in which:

Figure 1 shows the picture

Fig. 2 shows an arrangement of the invention transverse to the peria fiber web machine, two pulp dampers according to the invention mounted in the direction of the fiber web machine9

Figure 3

Figure 4 is a view in plan view of the mass-damper according to the invention, partially cut-away with a first embodiment of the locking means of the mass-damper of Fig. 3, when the casing of the flex-compensated roll is cut;

5a

Figure 6

And Fig. 5b are cross-sectional views of various embodiments of a guide shaft, showing a side elevational view of another part of the inventive mass absorber.

a first preferred embodiment of an arrangement according to the invention and a mass suppressor is shown. Another possible embodiment is described verbally at the end of the description.

20185055 prh 22 -01- 2018

The arrangement 1 according to the invention is preferably arranged in a fiber machine, in which the nip 102 formed by the two rolls 11 is preferably a press nip of a press or most preferably a nip of a calender. Controlling the vibrations of the nip forming rollers is particularly important with the calender, since often after the calender there are no post-treatment steps to correct the irregularities of the fiber web. In addition, the calender-deflected roll is coated with a soft coating to optimize the surface properties of the paper, which makes the deflection-compensated roll particularly susceptible to vibrations. The arrangement 1 according to the invention includes, as shown in Figure 1, two rolls 11 forming a nip 102, at least one of which is a deflection compensated roll 12, and a mass damper 10 arranged within the deflection compensated roll 12, the deflection compensated roll 12

20185055 prh 22 -01- 2018 for damping vibrations. The fibrous web 101 is derived from the nip

102 through.

In the first embodiment of Figure 1, the mass damper 10 according to the invention is fixedly attached to the stationary axis 16 of the deflection compensated roll 12. The purpose of the fixed attachment is to transfer the vibration of the deflection compensated roll 12 to the mass damper 10, which in turn begins to vibrate. By adjusting the oscillation frequency of the mass suppressor to correspond to the interference frequency of the deflection compensated roll 10, the mass suppressor 10 attenuates the vibration of the deflection compensated roll 12.

The mass suppressor 10 according to the invention includes a body 14 as shown in Figures 2, 3 and, for example, by bolts 54 secured to the side of the stationary shaft 16 15 of the deflection compensated roll 12 as shown in Figure 1. The mass damper 10 is secured to the side of the stationary shaft 16, since free space is only available on the side of the stationary shaft 16 within the sheath 104 of the deflection compensated roll 12. This puts its own limitations on the dimensioning of the mass absorber, the space used being longitudinally of the roll 20, but at the same time quite narrow and shallow in the transverse and vertical directions of the roll. The mass absorber according to the invention may have a width in the cross-direction of the deflection compensated roll of 80 to 150 mm, preferably 100 to 120 mm and a mass body length of 100 to 400 mm, preferably 100 to 200 mm. The entire length of the mass suppressor may be 800 to 1400 mm, preferably 1000

- 1200mm. The mass body weight is preferably 40 to 60 kg. The figure shows how the diaphragm 104 of the deflection compensated roll 12 is supported on the stationary shaft 16 by a bearing 106, and between the diaper 104 and the stationary shaft 16 there are means 108 for compensating the deflection 30 of the diaper 104.

In addition to the body 14, the mass suppressor 10 includes a resilient element

18, which in this case is a guide shaft 20. The guide shaft 20 engages within the body 14. For example, the frame may be two

20185055 prh 22 -01- 2018 Semiconductor structure with provision for guide shaft. The halves can be attached to each other with the same bolts as the frame attachment to the stationary shaft. The bolts simultaneously tighten the halves against the guide shaft, locking 5 in the guide shaft body. A mass body 22 is movably disposed at least partially around the guiding axis at the guide shaft 20 (or partially at the end of the guide member 60 as an additional mass 60). The mass member 22 in turn includes a hole / bore having a cross section 10 partially corresponding to the guide shaft. The guide shaft 20 is dimensioned so that the ratio of the mass of the mass body 22 fitted to the guide shaft 20 to the spring constant of the guide shaft 20 causes the mass damper 10 to oscillate, or oscillate, of the guide shaft 20. This allows the mass body 15 to move substantially parallel to the nip as it oscillates at the interference frequency of the roll. The guide shaft 20 has an unsupported elastic region 30 for its elasticity, from the outside of which the guide shaft 20 is fixedly supported on the body 14. In other words, the guide shaft 20 can be elastic only within its elastic region 30.

As shown in Figure 3, the mass suppressor 10 includes locking means 26 disposed at or adjacent to the stock body 22 by means of the locking means to lock the stock body 22 at a location at d spaced 25 from the body 14 to prevent the mass body 22 from shifting deflection compensated roll 12 at an interference frequency. At the same time, the transverse movement of the guide shaft of the stock body is also prevented, i.e. the stock body cannot vibrate on the guide shaft, which would consume both components.

The movement of the pulp body 22 on the guide shaft 20 is effected by the transfer means 24. According to the embodiment shown in Fig. 3, the transfer means 24 are a hydraulic cylinder 40 comprising a cylinder part 42 and a piston rod 44. Preferably, the guide shaft is provided with a bore 45 in the longitudinal direction through which the piston rod 44 is fitted. The guide shaft 20 is also provided with an elongated slot 61 passing through the guide shaft 20 in its transverse direction, whereby the piston rod 44 is secured by a pin 62 to the mass body 22. In this case, the cylinder part 42 of the hydraulic cylinder 40 is disposed in the longitudinal direction of the deflection compensated roll 10, with excess space available. In the figure, reference numeral 56 illustrates the connections of the hydraulic lines to the hydraulic cylinder 40 and the pulp body 22.

Alternatively to the positioning of the hydraulic cylinder 40 shown in Fig. 3, the hydraulic cylinder may be adapted as shown in Fig. 6 such that one end of the hydraulic cylinder 40 is pivoted by a joint 84 on a stationary axis of a deflection roll.

The attachment by means of the hinges 82 and 84 does not significantly stiffen the guide shaft and further allows the vibration movement of the mass body 22 essential for the operation of the mass damper to be substantially nip.

20185055 prh 22 -01- 2018

Instead of the transfer means shown in the figures, other types of transfer means which do not have a stiff guide shaft could be used in the mass suppressor according to the invention. These may be, for example, various chain-based solutions or cable solutions.

The function of the guide shaft in the mass damper is to act as a spring having a spring constant which is determined by the position of the mass body and the length of the elastic region. The guide shaft 20 may, as shown in Fig. 5a, be a shaft with a major cross-section, preferably bevelled on both sides of the guide shaft 20.

20185055 prh 22 -01-2018 with nip bevels 32. The bevels change the stiffness of the guide shaft so that the spring constant / stiffness difference of the guide shaft is different in the direction of the nip and perpendicular to the nip, making vibration easier to target in the desired direction, preferably 5 nips. In this case, the mass suppressor according to the invention provides a directed damping of the oscillation. Alternatively, the bevels 32 provided on the outer surface of the guide shaft 20 of Figure 5a may be modified by the longitudinal bores 86 of the guide shaft 20 of Figure 5b.

Figure 4 shows a preferred embodiment of the locking means of the embodiment of Figure 3. The locking means 26 include a locking member 34 for clamping the pulp 22 against the guide shaft 20, a spring-loaded locking actuator 36 for pushing the locking member 34 15 upon locking the pulp 22 and an external force releasing actuator 38 to release the locking actuator 36 by external force. In this case, the locking means 26 are integrated as part of the pulp body 22 as shown in Figure 3 and the aforementioned parts 20 are fitted inside the pulp body 66 as shown in Figure 4. The locking means 26 of Fig. 4 operate in such a way that the block of mass is spring-loaded. For this purpose, springs acting as spring-loaded locking actuators 36, preferably 25 disc springs 68 according to Figures 4 and 6, are supported against the ends 67 of the pulp body 66 and supported at both ends 67 against the rear piston 75. The disc springs 68 extend the rear piston 75 in the direction of the body 66 of the stock body 66, whereby the locking wedges 64 forming the locking member 34 against the rear piston 75 are wedged by Correctly dimensioned disc springs are achieved

20185055 prh 22 -01-2018 sufficient force to lock the mass member and eliminate radial play between the mass member and the guide shaft.

Unlocking requires external force, which is obtained by hydraulics. The rear pistons 75 are secured by rods to pistons 74 sealed by seals 78 so as to delimit a chamber 76 between the body 66 and a piston to form a release actuator 38 for locking means 26. The chamber 76 includes a hydraulic conduit 72 through which hydraulic oil can be pressure in the chamber pushes the pistons 74 and the rear pistons 75 attached thereto towards the ends 67, whereby the locking members 34 can move back into the body of the mass body 66, releasing the locking means 26.

In the pulp damper 10 according to the invention, adjusting the damper to the frequency of deflection of the deflection compensated roll can be done only by adjusting the position of the pulp 22 in the elastic region 30 of the guide shaft 20 or alternatively 20 by using additional masses 60

The additional masses allow rough matching of the oscillation characteristic frequency of the pulp body 22 of the pulp suppressor 10 to the right frequency range and the movement of the pulp body 22 on the guide shaft 20, in turn, fine tuning to the right characteristic frequency.

For adjustment, the arrangement 1 may preferably include a first vibration sensor 46 mounted on a stationary shaft 16 30 of the deflection compensated roll 12, which measures the vibration amplitude and frequency of the deflection compensated roll 12, and a second vibration sensor 48 is fitted to the pulley 22. 22 vibration characteristic frequencies.

20185055 prh 22 -01- 2018

The first vibration sensor 46 generates measurement data of the vibrations of the deflection compensated roll 12, while the second vibration sensor 48 generates the second measurement data based on the vibrations of the mass body 22. In addition to the first vibration sensor 46 and the second vibration sensor 48, the arrangement 1 preferably also includes software means 50 for comparing measurement data of the first vibration sensor 46 and the second vibration sensor 48.

Based on the measurement data comparison information, the software means 50 is adapted to control the transmission means for moving the mass body, whereby the characteristic frequency of the vibration of the mass body changes. The reference value may be calculated, for example, from the difference between the oscillation frequency ίτ of the deflected roll and the characteristic frequency f of the mass oscillation, and 15 mass pieces are moved closer to the frame on the guide axis if the reference value is positive and farther away from the frame if the reference value is negative. The hydraulic cylinder advantageously acting as transmission means may have an integrated position sensor which informs the software means of the position of the mass body 20 on the guide axis. Software tools have information on how much the vibration characteristic of a mass body changes per selected unit of measurement, and on the basis of that software tools can calculate the length of the required transmission. In addition to the aforementioned parts, the arrangement 25 preferably includes communication means 52 for providing information from the first and second vibration sensors to and from the software means and the transmission means. The communication media may be the standard factory communication buses, such as field buses. An amplifier may be provided between the communication means and the software means for amplifying the measurement signal of the first vibration sensor and the second vibration sensor. The once-tuned mass suppressor can be automatically tuned, for example, at hourly intervals

20185055 prh 22 -01-2018 avoids a change in the frequency of vibration of the mass body due to the slow creep of the mass suppressor, which gradually reduces the damping power of the mass suppressor.

Preferably, in the arrangement 1 of the invention, two mass dampers 10 are attached to the stationary shaft 16 of the deflection compensated roll 12 as shown in Figure 2. The mass absorbers 10 are preferably disposed on both sides in a mirror image relative to the center between the ends of the deflection compensated roll 12. In this case, the stationary shaft is symmetrically damped by the mass dampers 10 and the mass of the masses of the mass dampers is greater than the mass of the mass of a single mass dampener. The higher total mass of the mass members of the mass absorbers allows for more effective damping, since the efficiency of the damping depends in part on the mass of the mass block to the mass of the deflection compensated roll. The total mass of the mass pieces of the mass absorbers should be in the order of 1% to 3% of the mass of the deflection compensated roll, in order to achieve effective damping which cuts at least 90% of the maximum amplitude of the oscillation.

The vibration amplitude of the mass body may be a decade greater than the amplitude of the stationary axis of the deflection compensated roll. In practice, the amplitude of the oscillation of the deflection compensated roll is preferably less than 1 mm. The oscillation frequency of the mass body of the mass suppressor according to the invention is adjusted to the same frequency as the interference frequency of the deflection compensated roll. This frequency may be in the range 25 Hz to 200 Hz, preferably 50 to 150 Hz.

Fig. 6 shows another embodiment of a mass suppressor according to the invention, in which a single long guide shaft 20 is attached to the same frame 14 having elastic regions 30 on each side of the frame 14, each of which is provided with one mass.

20185055 prh 22 -01- 2018 Paragraph 22. Because in this embodiment, there is no space on the other side of the body 14 for the hydraulic cylinder acting as transfer means, each hydraulic cylinder 40 is provided with its own hydraulic cylinders 40 articulated between the body 22 and the body 14. The pivoting of the hydraulic cylinders 40 may be accomplished by means of pivots 82 and 84. In order to prevent the hydraulic cylinder from damping the vibration of the pulp body 22 on the guide shaft 20, the attachment of the hydraulic cylinder 40 to the pulp body 22 may also be effected by an oval hole 10 allowing the pulp body to move longitudinally along the guide shaft.

In another embodiment of Figure 6, the locking means 26 also differ from the embodiment shown in Figure 4. The locking means 26 of Figure 6 is implemented such that between the ends 67 there is a body 66 of a pulp body having an inner surface having a bevelled surface. A sleeve 70 with a second bevelled surface abuts against the bevelled surface and is pressed against the bevelled surface by means of disc springs 68 acting as locking actuators 34. The chamfer surface and the second chamfer surface change the direction of force so that the sleeves 70 push toward the guide shaft 20 to lock the pulley 22 on the guide shaft 20. The locking means 26 can be unlocked as in the embodiment of FIGURE 3 utilizing the external force 25 exerted by hydraulic pressure the sleeves 70 are then returned back towards the end 67 by hydraulic pressure, releasing the locking means 26. The sleeves may be partially split, thereby providing a greater clamping force than the uniform sleeves. Further, the fitting of the partially split sleeves with respect to the guide shaft does not have to be as accurate as the uniform sleeves should be.

The mass suppressor according to the invention is suitable for use with new deflection compensated rolls, whereby the openings required for its installation can be taken into account in the manufacture of the stationary axis of the roll. On the other hand, the mass suppressor 5 according to the invention is also suitable for use with already existing deflection compensated rolls, whereby the stationary axis of the roll must be provided with openings for attaching the mass absorber and provide connections for electrical and hydraulic power.

In another embodiment of the invention, the mass damper can be implemented such that the mass body is fixedly mounted on the guide shaft and the guide shaft is movably attached to the body. By means of transfer means, 15 guide axes can be moved through the body, whereby the mass body moves towards or away from the body, changing the distance between the mass body and the body and thereby the characteristic frequency of vibration of the mass body. In such an embodiment, the locking means is disposed on the body 20 and locks the guide shaft at a selected position against the body.

Claims (6)

A mass attenuator (10) for a bend-compensated roller (12) forming a nip (102) of a fiber web machine, said mass attenuator (10) 5 includes - a frame (14) for attaching the mass attenuator (10) to a stationary shaft (16) which is included in the bend-compensated roller (12) within the bend-compensated roller (12), a flexible element (18) attached to the body (14), - a mass element (22) arranged adjacent to said flexible element (18), characterized in that said flexible element (18) is a guide shaft (20), which comprises a flex area (30), outside of which flex area (30) the guide shaft (20) is attached to the body (14), to which the flex area (30) the mass element (22) has been arranged, and the mass attenuator (10) further comprises moving means (24) for moving a mass element (22) in the longitudinal direction of the guide shaft (20), and - reading means (26) for reading a mass element 20 (22) at a distance (d) from the body (14) by means of the guide shaft (20). Mass attenuator according to claim 1, characterized in that the guide shaft (20) is permanently fixed to the body (14) and The mass element (22) is arranged around the guide shaft (22) to be moved over the flex area (30) when said reading means (26) are arranged adjacent to the mass element (22) and the displacement devices (24) are arranged to move the mass element (22) along guide shaft (20). Mass attenuator according to claim 1, characterized in that the guide shaft (20) is movably attached to the body (14) and the mass element (22) is permanently fixed to the guide shaft (20), when said reading devices (26) are arranged in connection with the body ( 14) and the displacement means (24) are arranged to move the guide shaft (20) in its longitudinal direction relative to the body (12). 5 4. mass dampers according to any of claims 1 to 3, characterized in that the pulp element (22) is supported by means only one guide shaft (20). 5. mass dampers according to any of claims 1-4, 10 characterized by the guide shaft (20) is supported in only one place against bodies (12). 6. mass dampers according to any of claims 1-5, 2018 characterized by the flex area (30) extending from one end (28) of the guide shaft 15 (20) towards the other end (28) over a distance which is 40 - 80%, presumably 60 - 70% of the entire length of the guide shaft (20). Mass attenuator according to any one of claims 1 to 6, characterized in that said guide shaft (20) comprises on both sides. 20 of the guide shaft (20) bevels (32) to direct the damping and prevent the mass element (22) from rotating. Mass attenuator according to claim 2 or any of the subordinate claims of claim 2 4-7, characterized by that The reading means (26) comprise a reading means (34) for pressing the mass element (22) against the guide shaft (20), a spring loaded reading means (36) for pushing the reading means (34) upon reading the mass element (22) and a release device (38). using external force to release the reading means (34) by abolishing the force caused by the reading device (36) by external force. Mass attenuator according to claim 8, characterized in that said reading means (34) are partially split sleeves (70). 20185055 prh 21 -12- 2018 Mass attenuator according to any of claims 1-9, characterized in that said displacement means (24) is a hydraulic cylinder (40), which comprises a cylinder part (42). And a piston rod (44), said piston rod (44) being arranged in the longitudinal direction of said flexible element (18) through the flexible element (18) and said cylinder part (42) being attached to the body (14) on the body (14). 14) opposing side in relation to the flexible element (18). Mass attenuator according to any one of claims 1 to 10, characterized in that said mass element (22) is supported on the guide shaft (20) over a support length, which is 100 - 300, presumably 100 - 200 mm. Mass attenuator according to any one of claims 1 - 11, characterized in that the mass attenuator (10) comprises additional masses (60) which can be fixed to the end (28) of the guide shaft (20) or to the mass element (22) for rough adjustment of the mass attenuator (10). The vibration frequency of the mass element (22) when fine tuning occurs by moving the mass element (22) along the guide shaft (20). Arrangement (1) in a fiber web machine, comprising two rollers (11) forming between them a nip (102), of which a Roller (11) is a bend-compensated roller (12) including a stationary shaft (16) for supporting the bending-compensated roller (12) in the fiber web machine, a sheath (104) rotating around the stationary shaft (16), rotatably supporting man bolts (104) on the stationary shaft (16) and a mass attenuator (10) 30, arranged within the manifold (104) for attenuating the vibration of said bending-compensated roller (12), characterized in that said mass attenuator (10) is a mass attenuator (10) according to any of claims 1-12. Arrangement according to claim 13, characterized in that the arrangement (1) comprises two mass dampers (10) arranged inside the bending-compensated roller (12) to obtain a greater damping capacity. Arrangement according to claim 13 or 14, characterized in that the stiffness (20) of the mass damper (10) is different in the direction of the nip (102) and in its direction perpendicular to it for directing the damping in the desired direction, presumably in the nip (102). 10 direction.