FI119519B - Drum and vibration damper for a paper machine - Google Patents

Description

1 119519

The present invention relates to a roll according to the preamble of claim 1 for use in a papermaking machine, which roll comprises an elongate body portion 5 and a surrounding roll shell which is rotatably arranged in connection with the body part. The invention also relates to a vibration damper according to the preamble of claim 12, comprising a vibrating mass body, a spring portion to which the mass body is attached and a body portion to which a spring portion is attached.

In paper machines, the so-called "roll-offs" are commonly used. tubular rollers having a tubular roll shell and end portions fitted to the ends thereof with shafts attached thereto. The rolls can be rotatably mounted on the bearing via these shafts. On the other hand, as the rolls rotate and they are in nip contact with each other, harmful vibration occurs. The tuned mass damper (TMD), or dynamic mass suppressor, is a si-15 vibration damper known per se, and its use is a known method of damping vibration at a known frequency in a structure. The mass damper has a mass fixed to one end of the spring and a second end of the spring to be fixed to the mass to be damped. The problem is that if the excitation frequency changes, the tuning of the mass suppressor should also be changed accordingly.

US2004 / 0154479 discloses a passive vibration dampener adapted to rotate with the inner surface of such a hollow tube roll shell. According to the publication, the mass of the vibration dampener is at least 15% of the mass of the roll shell, whereby the increase in mass caused by the vibration damping is significant.

***; WO9849394, WO0042427 and WO0042228 disclose a solution in which an adjustable vibration damper is provided in a roller bearing housing. In these, the damping-s \ t nin is outside the roll, whereby it e.g. takes up a lot of space. In the solutions presented in the publications, adjustability is realized by changing the position of the pulp in the oscillating t · ·. 30 or alternatively by changing the mass. With relatively easy access to the damper • · * *; *, the tuning can be changed even while the machine is running.

• * '··· * The size of the mass is shown to be altered by introducing a liquid into the mass space [** ,. or by deleting it. WO9849394 mentions that the vibration dampener may be: * ·, · inserted inside the roll, but this makes adjustment difficult.

• f 35 2 119519 [005] In paper machines, the so-called. deflection compensated rolls in many applications. Such a roll has a substantially stationary shaft and a jacket rotatably disposed about it. Along the shaft there are hydraulic loading means disposed in the longitudinal direction thereof in the area covered by the shell. Thus, when the roll is in nip contact with, for example, another roll, the loading members can influence the nip force profile and compensate e.g. distortions in the nip force profile due to roll deflection. Typically, deflection compensated rollers are used, for example, in a press section and e.g. calenders. One such deflection compensated roller is disclosed in EP241422A2.

In deflection compensated rolls, particularly on the press section of a papermaking machine, when the roll is in nip contact with another roll, a typical form of vibration is one with the greatest amplitude in the middle of the roll. It would then be most advantageous to place the damper inside the roll. However, the problem is that the damper inside the roller is not easily accessible so that its tuning can be changed during operation. It would be conceivable to extend the damping frequency range of the mass suppressor by adding the damping of the damping itself, for example by using a viscoelastic spring material such as rubber or the like. However, there is a relatively high temperature inside the roll and also hydraulic oil, which firstly limits the range of materials used and secondly causes changes in the properties of the viscoelastic materials at long run.

• · This in turn changes the attenuator tuning and renders it ineffective.

In order to solve, among other things, the problems and drawbacks mentioned above, a new type of deflection-compensated roller with efficient vibration control has been developed. 25 and wherein the above-mentioned prior art problems are minimized.

It is also an object of the invention to provide a vibration damping device for changing the tuning frequency of vibration damping, even when the vibration damping device is very difficult to access, such as in a paper machine. deflection commands ··· φ within 30 retracted rolls.

* · ·

• M

The apparatus according to the invention is characterized by what is stated in claims 1 and 12.

♦ · * ♦ * • · * • · 3 119519

The roll according to the invention comprises an elongate body and a surrounding roll shell which is rotatably arranged in connection with the body. The roll of the invention is characterized in that at least one tuned mass damper is arranged inside the roll casing in connection with the body part. Typically, such a structure is in a deflection compensated roll.

According to one embodiment of the invention, at least first and second tuned mass suppressors are tuned to the first and second, different tuning frequencies of the roll body.

10

In this way, vibration damping over a wider frequency range is obtained.

Preferably, the first tuning frequency is 2 to 5% lower than the second tuning frequency. This ensures that the response of the damping is sufficiently uniform. In practice, particularly for the roller press section of the papermaking machine, the difference between the first and second tuning frequency is preferably about 2 Hz.

Under the operating conditions to be determined, the roll has a frequency of the largest amplitude of oscillation. According to one embodiment of the invention, the first and second tuning frequencies are selected such that one of them is higher and the other smaller than said • · \ **: frequency of maximum oscillation. In this way, the attenuation occurs evenly around the highest frequency of · ·: .ϊ · oscillation. Preferably, the number of mass suppressors is always ·: * at least 3.

The roll according to the invention preferably comprises means for compensating the roll envelope deflection: ** ', by means of which the nip load profile can be kept optimal. The roller * ·· is particularly well suited for use in a position where it is so called. nipple roll, that is, in a nipple • \ # tact with another roll. Preferably, the roll is a press roll or a calender roll.

··· • · · · ··· *. According to one embodiment of the invention, the mass damper comprises a vibrating mass body, a spring member to which the vibrating mass is attached and a body member, '' ** to which the spring member is attached. This type of mass suppressor can be further developed with ·· • * ·· provided that the spring element is adjustable! an adjustable stiffening member, by means of which the adjustable portion of the spring member can be arranged to be substantially inelastic to a maximum of 35 or more. This achieves the effect that pre-tuning 119519 4 may not be necessary and, on the other hand, the tuning can be fine-tuned while the paper machine is running. Further, this allows the mass dampers to be constructed similarly and to be tuned by setting the desired portion of the spring member substantially stiffer.

5

According to one embodiment of the invention, the pulp body comprises a fluid space into which a medium can be introduced to change the pulp body mass. This also allows the pulp suppressor to be changed while the paper machine is running.

Preferably, the spring portion of the mass absorber comprises a rod-like body, which at the first end is fastened to a body part where the stiffening member comprises adjustable! a member arranged at the first end towards the second end in relation to the surface of the rod-like body. Such a member may be a second rod-shaped body which is engageable with the first rod-shaped body.

15

Preferably, the spring portion of the mass suppressor is metal, wherein the frequency range damped by the single mass suppressor is relatively narrow.

Other features of the roller and pulp suppressor according to the invention will be apparent from the appended claims.

As used herein, a papermaking machine refers to various fibrous web manufacturing or processing equipment or parts thereof, such as papermaking machines, cardboard machines, calendars, and * · i.i · press parts. A tuned mass suppressor is defined as a vibration damper, ··: * ·· 25 based on a vibrating mass and having a main damping frequency adjustable.

Advantages achieved by the invention include e.g. the following: ***: - Vibration damping is effective especially when the deflection compensated roll is, * ·. 30 in nip contact with another roll * * ♦ - Vibrator tuning does not change under operating conditions • ♦ j "Vibrator tuning can be performed with the same medium as the roll nipple i '** force adjustment • ♦ * *« • ·· • · 119519 5

In the following, the invention and its operation will be described with reference to the accompanying schematic drawings, in which Fig. 1 shows a deflection compensated roll according to a preferred embodiment of the invention, Fig. 2 shows a body of a deflection compensated roll in Fig. Fig. 5 shows an embodiment of the invention, Fig. 7 shows another embodiment of the invention, Fig. 8 shows a third embodiment of the invention, Fig. 9 shows a fourth embodiment of the invention, Fig. an embodiment of the invention, and FIG. 10 illustrates an embodiment of the invention in a nip position.

The deflection compensated roll 10 according to a preferred embodiment of the invention, as shown in Figs. 1 and 2, comprises a frame portion 12 and a surrounding roll shoe 14. The frame portion extends out of both ends of the roll sheath and the roll can be supported on the paper machine body. at the ends of the body. The body part is stationary and the body is extensively wound to rotate with respect to the body part. The roll also comprises means for compensating for the deflection of the roll shell 14 iT. Figures 1 and 6 show the hydraulic means 17 'by which the deflection of the roll shell can be compensated and / or profiled by the nip force of the roll shell. The devices in question are only shown very schematically, since this type of or

M · I

The 25 pump-compensated rollers are known per se for their basic structure. Frame 12 is successful -. * · *. 1 and 2, as shown in Figures 1 and 2. It is understood that the invention may also be applied to other model body parts. These include:. for example, a straight body with side surfaces, as long as there is sufficient space to install the • ♦ ·. ··· mass absorber inside the roll cover.

• * · * ·. The body 12 is formed by a web 12.1 and chords 12.2 such that the web interconnects the chords from their central area with respect to each other at approximately right angles. The body is arranged such that the force exerted by the hydraulic means: * ♦., And when the roller is used, the direction of the nip load is substantially parallel to the web.

• · 35 119519 6

Preferably, a plurality of excited mass dampers 16 are attached to the roll body portion within the roll shell, and the mass dampers 16 are attached to the body web 12.1 and the direction of vibration damped by them coincides with the web direction. The mass dampers may be arranged symmetrically with respect to the bending center line 18 of the body 12, whereby their function is substantially independent of the deflection of the body. The mass absorbers are of such a size that they can be fitted in the space between the body part and the roll shell 14.

This embodiment employs mass damping arrangements, which are illustrated in more detail in Figure 3. The arrangement of the embodiment of Figure 3 comprises 10 mass damping body members 20. A spring member 22,22.1,22.2, which in this embodiment comprises two separate leaf spring units, is attached to the body member. The leaf spring unit may consist of one or more separate thinner spring plates. Preferably, the arrangement is such that the direction of the leaf spring assembly disposed in the roll is parallel to the body of the roll. The direction of the leaf spring unit is the direction of the straight through the fixed end of the leaf spring unit and 15 oscillating heads.

The body part 20 of the mass suppressor shown in Figure 3 is an elongated body, the ends of which are provided with spring members 22.1, 22.2 from their central members, each spring member being practically two springs on each side of the body member.

Vibrating mass members 16.1 * · Y * i and 16.2 are also provided on both sides of the frame member, which are fastened at their ends to the ends of each spring member. The ends M · v of the spring members: 22.11, 22.21 and the outer sides 16.21 of the vibrating mass body extend substantially equally from the body member 20, whereby the mass body is disposed mainly between the spring members 22.1 and • · ·, ·. In this way, the use of space is very efficient. The mass members are shaped such that only the point of attachment of the mass member to the spring member is in contact with the spring member and elsewhere there is a space for vibration between the mass member and the spring member. Fig. 2 shows three pieces of mass suppressor arrangements shown in Fig. 3 attached to the roll body 12.1.

According to the invention, the mass suppressor 16, and in particular its spring member, is made of metal, * · * I "preferably steel. This provides the advantage that the mass suppressor behaves substantially the same under installation and operating conditions. and its vibration damping: '* · long-lasting properties The temperature of the deflection-compensated roller under operating conditions • · Y ·· is in the order of 60 ° C and its internal parts are in constant contact with oil 7 119519 (lubrication / hydraulics). the tuning of the mass suppressor also applies under operating conditions, and its tuning frequency is also maintained.

Figures 4 and 5 illustrate the basic idea of an embodiment of the invention. The horizontal axis of Ku-5 vion 4 shows the relative oscillation frequency of the oscillating body (oscillation frequency / characteristic frequency) and the vertical axis the relative deviation (body deviation / substrate deviation). Figure 5 illustrates a model with a piece 50 supported on a substantially rigid substrate 52. The strut pattern comprises a base spring 54 and a damping 56. The position of the substrate is represented by x52, and the vibration response of a body vibrating without damping 10 is plotted in Fig. 4. , which shows that the amplitude of the oscillation is significantly large at the singular characteristic frequency, i.e., when the relative oscillation frequency is 1,

When the vibrating body of the model is provided with at least the first and second mass suppressors 16 tuned in accordance with the invention, the situation changes significantly.

In the model shown in Fig. 5, the mass pieces 16.1,16.2,16, N of the mass absorbers are arranged in the piece via a spring 58.1, 58.2, 58.N. Spring support is described in this model to include a spring and damping element. The deviation of the mass suppressor is depicted in Fig. Xi, x2, xN. However, the attenuation of each individual mass absorber lies within a very narrow frequency range because the spring member is a metal, preferably steel, according to the invention. In order to extend the frequency range of the vibration damping, each mass suppressor is tuned to a slightly different frequency so that together they cover a wider frequency range. In a paper machine application, these separate ϊβί 'mass suppressors are preferably tuned to a frequency of about 2 Hz.

The effect of two separate mass suppressors can be observed in the curve 4.2 of Figure 4.

• · *** · The peak value of the vibration amplitude is now significantly lower.

j *. ^ When the number of masses 16.N of the mass suppressors is increased and tuned each * · * ·. single mass absorber or mass absorber mass piece for different frequency, get- ·. 30 d more effective and smoother. This can be seen from the curve * · · *; When a plurality of mass dampers are used, they are preferably tuned such that at least a portion of the mass dampers have tuning frequencies above and below the maximum vibration frequency of the roll. A mass 16.N tuned to a particular frequency may be: \ [a single piece or it may consist of several separate interconnected parts.

35 8 119519

The mass suppressor can be further developed such that the tuning of the mass suppressor is arranged to be set or adjusted during roll operation. Figure 6 illustrates an embodiment of the invention which operates in this manner. Here, the mass pieces 16.1 and 16.2 are supported between the coil springs 68. Obviously, instead of helical springs, for example, disc springs can also be used.

The pulp bodies are provided with a fluid chamber 60. A fluid can be introduced into the fluid chamber to change the mass of the pulp body. In this way, the fine tuning of the final tuning can be accomplished by adjusting the volume of the medium, whereby the mass suppressors to be tuned to attenuate different frequencies can be made essentially similar, and no special pre-tuning is necessary.

The medium 60 is structured in such a way that the movement of the medium therein with respect to the mass body itself is at least limited, preferably prevented. This is important 15 especially when the space is not filled with medium so that the mass body and the medium behave as much as possible in a uniform mass. In Figure 6, the fluid space is provided with a filler 62 which slows down the movement of the medium.

Preferably, the medium is oil, whereby the same oil source as for other roll oil applications can be used. In this case, the arrangement comprises oil supply lines *. *: * 64 fitted to roll body 12. Inlet conduits 64 are disposed above supply conduit 66 in pulp · * · V · such that oil escaping from inlet conduit * into supply conduit 66. To remove medium from the medium, the bulk body is provided with outlet conduit 72 The pulp body is also equipped with a media control system * ft • * ·. 25, which, for example, affects the throttling of the supply channel. Control System J. **: comprises an oil level gauge, for example based on the measurement of the surface height.

The control system may also operate on the overflow principle, whereby the location of the overflow opening may be adjustable (not shown). The oil may be introduced into and out of fluid space 60 via channels provided in springs.

. *. 30 *****

In applications where the medium is not an oil, but some other substance, i '1 * is a closed medium conveying conduit in and out of the medium. Instead of filling ί ** 62, the medium can be provided with, for example, a piston or membrane partition wall, which allows the medium to vary in size according to the amount of medium and the medium to be completely limited in space.

9 119519

Fig. 7 shows another embodiment of the invention, wherein the tuning of the mass suppressor is arranged to be set or adjustable during roll operation. Here, instead of the mass of the mass body, the effective length of the spring member is changed, i.e. the portion of the spring which is resilient and the part which is substantially inelastic is adjusted. In the embodiment of Fig. 7, the mass damper shown in Fig. 3 is modified such that the spring member is provided with adjustable! an adjustable stiffening member 74, by means of which the adjustable portion of the spring member can be arranged to be substantially inelastic. Here, the stiffening member comprises an auxiliary spring 76 in connection with each of the spring portions 10 22.1, 22.2. The auxiliary springs are also attached to their center portion in the same manner as the spring parts and the auxiliary springs and spring parts 22.1,22.2 are also attached to one another from their central parts. The auxiliary springs are curved such that they extend away from the spring springs. At the ends of the auxiliary springs is a lever 78 comprising two levers. These levers are articulated at one end to the ends of opposite auxiliary springs and at one end to each other. The total overall length of the levers-15, when engaged, is such that the auxiliary springs can be pressed against the spring members.

The stiffening member also comprises a hydraulic actuator, a hydraulic cylinder 80, at the ends of which the links of the levers are connected. This results in a change in the bending of the auxiliary springs as the length of the actuator 80 changes as indicated by the arrows in the figure. As the auxiliary springs straighten, they position themselves further and further against the struts, the auxiliary springs supporting the springs over a certain length. the greater part of the spring member 22.1,22.2, is stiffened.

The stiffening means may also be provided with support rollers 82. The support rollers control the deflection of the auxiliary springs so that the support rollers are arranged to run along the surface of the auxiliary spring. : \ tt The support rollers are practically attached to a movable subframe which is not shown for clarity. ** ·.

Fig. 8 shows an arrangement according to yet another embodiment, in which the tuning of the mass damper is arranged to be adjustable or adjustable during roll operation. Here, the auxiliary springs are secured at their ends by means of a rod 86 connecting the auxiliary springs 84, so that in this embodiment the auxiliary springs 35 76 are bent inwardly towards each other. Here, the contact lengths of the auxiliary springs and springs 22.1,22.2 10 119519 are adjusted by changing the position of the support rollers. In practice, the support rollers are arranged in a subframe and are provided with an actuator, which allows the support rollers to be moved along the surface of the auxiliary spring.

Fig. 9 shows an arrangement according to yet another embodiment, wherein the excitation of the mass suppressor is arranged to be set or adjusted during the use of the roll. This embodiment otherwise corresponds to that shown in Fig. 7, but the form of the linkage 78 at the ends of the auxiliary springs is such that they comprise a cam portion 90 provided with a guide surface 88 which is concave to the auxiliary spring surface. Here, the cam part, through its guide surface, supports the auxiliary springs and always keeps them in a certain position.

The vibration characteristics of an existing papermaking machine can be improved by a method in which the deflection roll of the papermaking machine is removed from the papermaking machine, the roll being disassembled at least to the extent that its shell is removed. Thereafter, if necessary, fastening surfaces for fastening the mass dampers are machined to the roll body. The requisite number of pulp clamps according to the invention are mounted on the mounting surfaces, the roll is reassembled and reinstalled on a paper machine. In order to successfully scale the pulse key-20s on a paper machine with the roll in question, before removing it, · · *. **: it is advantageous to make oscillation measurements to identify frequencies that are necessary or desirable.

10 shows a deflection deflection according to an embodiment of the invention.

•%. 25 compensated roll 10 as nip roll 10 '. It is then in a nip contact to form a nip N

with another roll 11. The fibrous web W is arranged to pass through the nip N for example to modify its properties or to dewater the nip.

The above are only some of the most preferred embodiments of the invention. So

III

It will be understood that the invention is not limited to the above embodiments, but that it can be applied in many ways within the scope defined by the appended claims.

* · • · M »• f« «t • ·· ♦ • ♦ · • ♦ · • ·

Claims (20)

1. Vais (10, 10 ') for use in a paper machine, the roller comprising an elongated body part (12) and a roller sheath (14) $ which is rotatably adapted in connection with the body part, characterized in that at least one tuned mass attenuator (16) is provided within the roller sheath in connection with the body part. Vais according to claim 1, characterized in that at least one first and a second tuned mass attenuator (16) are arranged in conjunction with the body part (12), which mass attenuators are tuned to a first and a second tuning frequency which are different. Vais according to claim 2, characterized in that the first tuning frequency is 2 - 5% lower than the second tuning frequency. 15 Roll according to Claim 2 or 3, for which the rolling frequency of the highest vibration to its amplitude can be defined under operating conditions, characterized in that the first and second tuning frequencies are selected such that one of them is higher and the other is lower than said frequency of the highest vibration. • · • · · *. „20 • · 1 : 5. Roll according to any of claims 2-3, characterized in that the difference between the ψ first and the second tuning frequency is about 2 Hz. • m · · · · · · · · · «• ·: 1 ·· Roll according to any of claims 1-3, characterized in that the mass attenuator comprises at least one vibrating mass body (16.1, 16.2), a spring part (22.1, 22.2) to which the vibrating mass is attached, and a body part, to which the spring portion is: · 1: fixed. • · ··· • · · · e ·· 7. A roller according to claim 6, characterized in that the spring part (22.1, 22.2) is provided. 30, with an adjustable stiffener (74), by which the adjustable portion of the spring portion can be made substantially stiffer than the other portion thereof. e · e e · · · · · · · 2 1: Roll according to claim 6, characterized in that the mass body comprises a space (60) for medium, into which space the medium can be directed to change the mass of the mass body (16.1, 16.2). 119519 Vais according to any of claims 2 to 4, characterized in that the number of mass dampers (16) is at least 3. Roll according to any of the preceding claims, characterized in that the roll (10) comprises means (17) to compensate for the bending of the male thread. Roll according to any of the preceding claims, characterized in that the roll is a nip roll (10 '). 10 Vibration damper (16) comprising a vibrating mass body, a spring part, to which the mass body (16.1, 16.2,16.N) is fixed, characterized in that the spring part is provided with an adjustable stiffening member (74), through which the adjustable portion of the spring part can be made. substantially stiffer than the other portion thereof. Vibration damper according to claim 12, characterized in that the spring part (22) comprises a closed body, the first end of which is fixed to the body part (20), and that the stiffening member (74) comprises a member (76) arranged in connection with the surface of the closed body. ) which extend controllably from one end to the other • · 20 end. • · · * Vibration damper according to claim 12, characterized in that the spring part (22) comprises a first closed body, the first end of which is attached to the body part, and that the stiffening means (74) constitutes a second closed body which can be brought into contact with!, .. in the first closed body of the spring part (22). : V Vibration damper according to claim 12, characterized in that the vibrating mass body (16.1, 16.2, 16.N) is provided with a space (60) for medium as well as ···, with an inlet and an outlet (66; 72), through which medium can be introduced into and discharged from the space. too medium to change the weight of the vibrating mass body. • e • · »* · • · ·! 16. Vibration damper according to claim 15, characterized in that the liquid space ^ · e * · * in (60) is arranged so that it has a variable volume so that the medium in the space is completely delimited in the space. 35 119519 Vibration damper according to any of claims 12 to 16, characterized in that the spring part (22) is of metal. Vibration damper according to claim 13, characterized in that the spring part (22) 5 is a leaf spring (22.1). Vibration damper according to claim 15, characterized in that the spring part (22) is a helical spring (68). Vibration damper according to claim 12, characterized in that a hydraulic actuator (80) is arranged to act as an actuator for the stiffener (74). e «• e · • · · e · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · e • eee · eee «·· • · ee • ee • ··· • eee · · • • e * ♦ · ee * ·· e • e · • · ♦ • · e · e · • e · • ♦♦ • e