EP2577078A1

EP2577078A1 - Roller and method for avoiding its vibrations

Info

Publication number: EP2577078A1
Application number: EP11711514.7A
Authority: EP
Inventors: Jochen Niemann; Lars KRÜGER; Rolf Van Haag
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2010-05-31
Filing date: 2011-03-25
Publication date: 2013-04-10
Also published as: CN102959257A; DE102010029492A1; WO2011151092A1

Abstract

The invention relates to a roller for treating a fibrous web with a circulating hollow roller shell (4) which is mounted on a rotationally fixed axle (5), wherein the annular chamber (7) between the shell (4) and the axle (5) is divided by at least two axial seals (6) into at least two chambers (8, 9) which can be filled with pressure fluids at different pressures in order to achieve a desired roller deflection. In order to reduce the vibrations at the shell of the roller during operation, there is at least one actively actuable chamber-volume varying device (2).

Description

Roller and method for avoiding their vibrations

The invention relates to a roller for treating a fibrous web having a circumferential, mounted on a rotationally fixed axis hollow roll shell, wherein the annular space between shell and axis is divided by at least two axial seals in at least two chambers, which to achieve a desired roll deflection with Druckflui- the different pressure can be filled.

The invention further relates to a method for preventing vibrations in a system constructed from this roller and a counter-roller.

The speech is therefore of a in professional circles as "floating roller" or "S-roll" designated roller. Nowadays, these rolls are often used in narrower calenders (based on the web width, the so-called CD direction). The differential pressure in the two chambers is sufficient to achieve a deflection that substantially conforms to the curvature of the backing roll.

The two longitudinal seals in an S-roll are known. They allow the different pressure build-up in a crescent-shaped chamber facing away from the nip and facing away from the nip. In many cases, they even allow a lifting movement of the jacket, without the tightness is lost. In order to avoid non-uniformities in the temperature profile on the roll shell, the oil which is supplied to the higher-pressure chamber from a roll neck side, fed back via the second chamber at lower pressure. With broad calenders, this type of roll is generally no longer sufficient to achieve a desired transverse profile of the fibrous web, so that so-called "Nipco rolls" have to be used by the applicant, which are considerably more complex and involve a more complicated application. In these rolls, individual hydrostatic support elements are distributed along the axial length of the axis and act individually or in groups against the shell to correspondingly deform it The roll improved in the present invention is an S-roll Due to the fact that today's calenders have to run faster and faster, machines with these rollers are more likely to experience barring phenomena that are previously unknown and that result from natural oscillations of the entire system.

There are numerous paper-handling machines consisting of two rolls in which various attempts have been made to avoid vibrations and have also been registered for industrial property rights. First, there are the systems that try to dampen the roll shell over its storage. Here, for example, DE 296 24 490 U1 and DE 198 21 854 C1 called. Unfortunately, it is hardly possible to dampen vibrations of the system at the relevant frequencies between 100 and 400 Hz via a typical rolling bearing (usually spherical roller bearings). Even active systems that introduce forces into the axle or bring a bending moment into the axle have little chance of success because the forces or bending moments can not be transmitted via the spherical roller bearings. Conversely, usually no disturbing oscillation of the roll mantle can be transmitted to the axis and then dissipatively destroyed there. Therefore, swing the roll shell at the occurrence of a barring problem on the roller almost undisturbed.

The measures described are therefore not suitable for S-rolls, to actively or passively combat vibrations of the roll shell in the range of 100 to 400 Hz, since the large volume of oil inside the floating roll prevents stiff coupling of the axis and rotating mantle. The additional air that is added to the system also prevents a sufficiently high oil rigidity in the range of> 900 N / mm ² .

For this reason, even with narrower calenders, rolls with individual hydrostatic support elements over the axial length are used for anticipated vibration problems.

DE 295 09 545 U1 discloses a roller with a vibration damper, in particular for producing or treating fibrous webs, e.g. Paper or board webs, known. It is also a roller with a stationary central axis and with a roller shell rotating about this central axis. In the central axis is a series of e.g. provided cylindrical pressure chambers which extend in the radial direction and each receive a radially displaceable support member. Each pressure chamber can be filled with a pressure fluid / transfers a hydraulic support force from the central axis via the support member on the roll shell, so as to be able to adjust a deflection of the roll shell targeted. Instead of several pressure chambers, each with a support element, a single elongated pressure chamber with a single elongated support element may be present.

For supplying the pressure fluid into the pressure chambers, there is, for example, a centrally arranged feed channel in the stationary central axis The damping is therefore passive, and the effort involved in producing and later controlling such a roller is great.

Another type of roller with internal active actuators for damping vibrations can be found in DE 100 08 800 B4. Rolls of the type described therein can be used in calenders. However, the use is expensive and it requires a considerable constructive and manufacturing effort. One way to selectively adjust a deflection is not given in this type of roller.

It is the object of the invention to reduce the vibrations on the shell of an S-roll during operation.

The object is achieved by the device with a roller, in which at least one actively controllable Kammervolumenveränderungseinrich- device is present.

Such an actively controllable chamber volume changing device creates the possibility of achieving short-term pressure surges by changing the volume of the chamber filled with a pressurized fluid. These pressure surges can produce an antiphase oscillation and thus extinguish the pressure pulsation, which is caused by the first axis frequency or by the first contact natural frequency of the system. At least the volume change, which is caused by the Kammervolumenver- changing means, approximately 90 ° out of phase between the vibrations of the roll shell and the oscillation of the axis can be adjusted, so that an optimal damping is achieved. A useful damping is expected at a phase offset of at least 50 ° to 130 °. In a system having a mating roll, that is, for example, a soft calender, the actively controllable chamber volume changing device can generate active phase-shifted counter-vibrations from inside the S-roll, which lead to a significant reduction in the oscillating movements.

Preferably, the chamber volume changing means comprises a membrane. Such a membrane makes it possible to change the volume in a chamber easily and, above all, quickly and precisely. It is important that the volume of the chamber pulsating, so adapted to the occurring vibrations of the roller, can be changed. The membrane, which may also be conceptually formed by a metal lid, is preferably round or quadrangular. Of course, composite materials made of plastic and metal are suitable for the membrane. In many cases, it makes sense to bias the metal membrane / the metal cover hydraulically, mechanically, piezoelectrically or by elastomeric materials or pressure accumulator.

Preferably, the membrane is movable in such a way that a chamber volume can be increased or reduced by 0.01-0.5%. Such a small change in volume has proven to be sufficient to extinguish the vibrations in an S-roll almost completely.

It is advantageous if the membrane is sealed in a recess of the axis all around. Within a depression of the axis, for example a bore, a membrane that is sealed all around is particularly easy to implement. It can be between two rings be clamped gene or frets. Yet it still has the freedom to keep the membrane surface movable in order to be able to change the volume in a chamber. It is contemplated to bias the diaphragm over the pressure of the pressurized fluid in the chamber.

It is favorable if at least one actuator is connected to the chamber volume changing device. For example, the actuator can tie directly to the membrane and move it. As a result, vibrations in the roller can be countered very quickly.

It is possible that the actuator is capable of exerting pressure on the jacket with hydraulic, pneumatic or electromagnetic means. These agents are used in a proven manner and are relatively easy to handle and wear. Each calender also has a hydraulic, pneumatic and electrical supply anyway. However, it is particularly advantageous if the actuator comprises at least one piezoelectric element. The expansion of piezoelectric elements can be controlled quickly and precisely by electrical means. The piezoceramics are round or preferably rectangular in shape. The stack height is 5 to 100 mm. The power electronics are housed outside the roller in a control cabinet. Via a cable channel, a secure power supply can be ensured. The operating voltage of the actuator is +/- 10 to +/- 1000 V. The actuators can be grouped together, which are driven together by a power electronics or are individually controlled. The following solution is particularly easy to produce: a cut is made in the axis in the CD direction. Subsequently, an insert is made, which is inserted into the milling and includes all actuators. The pressure fluid conducted through the roller can additionally serve as a cooling medium for the actuators.

Preferably, the actuator in the recess is located radially further inwardly of the axis than the diaphragm. As a result, he is not under the direct pressure of the pressurized fluid. Rather, he is protected and working without friction housed in the recess of the axle.

Advantageously, it is ensured that the depression has a cooling fluid inlet and outlet. The pressurized fluid conducted through the roller can, in addition to its other tasks, serve as a cooling medium for the actuators. In this case, elaborate separate cooling bores with external connections are avoided. Preferably, the pressure chamber is supplied via a pressure fluid line, in which there is a throttle element. Due to vibrations forces on the support element can be intercepted with the help of these chokes. The throttles thus additionally dampen in a passive manner and can be, for example, bore, sieve or annular gap throttles.

Advantageously, a sensor arrangement is mounted on or in the roller, which is in communication with a control device which controls the at least one actuator. As a sensor arrangement, the most diverse measuring apparatuses are to be understood. This ranges from the tachometer to the acceleration or speed sensor of the vibrations, touching as non-contact. The signals of the measurement results are forwarded to a control device, which provides for an effective active activation of the actuator to intercept the roll jacket vibrations. It is favorable if the pressure exerted by the actuator pulsates via the diaphragm to the pressure fluid of a chamber during operation. Here, it is preferable to select a frequency which interferes with the system natural frequency in order to cancel the barring-forming vibrations. It has been found that the pulsation of the actuator preferably takes place in a specific frequency band. It is provided that the pressure exerted by the actuator pressure on the roll shell in operation at a frequency of 100 to 400 Hz pulsates. The rolls are usually intended to form a nip with a counter-pressure element, for example a second roll, in which a fibrous web can be treated. So that the profile in the nip is not unduly influenced, it is advantageous if the effective direction of all actuators does not go through the nip.

Preferably, the actuators are distributed symmetrically over the length and / or circumference of the roller. This avoids influences that unevenly affect the width of the fibrous web. If the roller only had a "belly" through the actuator on one side, the web would possibly be more compacted at this point than elsewhere.

Procedurally, the object of the invention is achieved by the features of claim 12. Thus, the vibrations are avoided in a roller according to claim 1, characterized in that the volume of a chamber is changed pulsating. Each roller has a characteristic natural frequency and its own rigidity. Nowadays, these can be determined mathematically in a simple way. For the natural frequency of the roll shell of the S-roll and its storage is an important factor. By an additional pressurization via a volume change in the chamber, for example by means of an actuator and a Membrane, the stiffness and thus the natural frequency can be greatly changed, which in turn means that vibrations are avoided. It has been found that in systems, for example a calender, it is sufficient to avoid most oscillations resulting from natural frequencies with a pulsating volume change of the chamber by means of an actuator and a diaphragm.

It is advantageous if, in the change in volume to activate the vibration avoidance and the pressure in the pressure chamber is changed. A pulsating pressurization of the jacket by the pressurized fluid, when set to the correct frequency, can almost completely cancel the vibration of the jacket.

Preferably, the expansion of the chamber volume changing device is regulated based on vibration measurements. This allows a more targeted and frequency-controlled pulsating pressurization on the roll shell, which dampens the resulting vibrations even better. The invention will be explained in more detail below with reference to exemplary embodiments with reference to the drawing. This shows in the figure

a schematic sectional cross-sectional view of an S-roll according to the invention.

The roller 1 works together with an indicated only as an arrow counter-pressure element 3, for example, a second roller to treat between them in a so-called nip a fibrous web. The roll 1 has a rotating roll shell 4 and a fixed axis 5. Between the two longitudinal seals 6 are provided, which share the annulus 7 in an upper chamber 8 and a lower chamber 9. These chambers are filled with a pressurized fluid, usually oil, under different pressure. As inlet and outlet channels of these chambers 8, 9 for the pressurized fluid, the channels 10 are provided. Different pressures in the chambers 8 and 9 allow the roller 1 a deflection which can be adapted to that of the counter-pressure element 3. The system of roller 1 and counter-pressure element 3 tends for a variety of reasons, such as unevenness of the treated

Fibrous web or discontinuities in the roll, to vibrations. These are difficult to dampen over storage. Therefore, an actively controllable chamber volume change device 2 is used for this purpose, which is housed in a recess 13 of the axis 5. The chamber volume change device 2 consists of a laterally sealed in the recess 13 membrane 12 and an actuator 1 first The actuator is composed essentially of piezoelectric elements 15, which can be controlled via power lines 16. The operating voltage of the actuator is +/- 10 to +/- 1000 V. About the actuator 1 1, the diaphragm 12 can be moved to increase the space in the chamber 8 in accordance with the vibrations or reduce. In this case, it is preferable to increase or decrease the chamber volume by 0.01-0.5%. The difference in pressure created thereby acts as a pulsating measure against the vibrations, either in antiphase to extinguish the vibrations, or out of phase by about 90 ° in order to damp the vibration. The chamber volume change device 2 thus actively works against the vibrations.

The membrane 12 is held around the surface of the axis 5 within the depression 13 and is surrounded by an annular seal 14. sealed, so that the pressure from the chamber 8 can not act directly on the actuator. The chamber volume extends over the half-moon-shaped half annular space 7, up to the membrane 12. This active vibration damping can also be supported by chokes are not shown in the inlet or outlet 10 of the chambers arranged in the drawing. Furthermore, lines 17, 18 from the chambers 8, 9 to the actuator 1 1 are provided. The pressurized fluid, which flows from chamber 8 via the line 17, past the piezoelectric element 15, flows through the line 18 into the chamber 9 with the lower pressure, accordingly also cools the actuator 1 1.

A sensor arrangement 19 for measuring vibrations advantageously sends its measuring signals via a control line 20 to a control device 22, which in turn - indicated via the control line 21 - ensures that the chamber volume changing device 2 is supplied with a pulsating pressure to the pressure chamber space 8 such that the Oscillations of the system are reduced interfering. Thus, a counter-vibration with pressure on the jacket 4 is introduced via the chamber volume change device 2. Suitable sensors are acceleration sensors, capacitive sensors, pressure sensors, optical sensors, etc.

The actuator 1 1 does not have its effective direction towards the nip formed with the counterpressure element 3. As a result, negative pressure influences of the chamber volume change device 2 on the treatment of the fibrous web are avoided. LIST OF REFERENCE NUMBERS

1 roller

2 chamber volume change device

3 counter-pressure element

4 roll jacket

5 axis

6 longitudinal seal

7 annulus

8 upper chamber

9 lower chamber

10 channels

1 1 actuator

12 membrane

13 deepening

14 seal

15 piezo element

16 power line

17 cooling fluid supply line

18 Kühlfluidabführleitung

19 sensor arrangement

20 control line

21 control line

22 control device

Claims

claims

1 . Roller for treating a fibrous web with a circumferential, hollow roll shell (4) mounted on a non-rotatable shaft (5), wherein the annular space (7) between shell (4) and shaft (5) through at least two axial seals (6) in at least two Chambers (8, 9) is divided, which are filled to achieve a desired roll deflection with pressurized fluids of different pressure, characterized in that at least one actively controllable chamber volume changing means (2) is present.

Roller according to claim 1, characterized in that the chamber volume changing device (2) comprises a membrane (12).

Roller according to claim 2, characterized in that the membrane (12) is movable such that a chamber volume can be increased or reduced by 0.01-0.5%.

Roller according to claim 2 or 3, characterized in that the membrane (12) in a recess (13) of the axis (5) is sealed all around.

Roller according to one of claims 1 to 4, characterized in that at least one actuator (1 1) with the Kammervolumenverände- tion device (2) is connected.

6. Roller according to claim 5, characterized in that the actuator (1 1) comprises at least one piezoelectric element (15).

7. Roller according to one of claims 4 to 6, characterized in that the actuator (1 1) in the recess (13) radially further inside in the axis (5) is arranged as the membrane (12). 8. Roller according to one of claims 4 to 7, characterized in that the recess (13) has a Kühlfluidzu- and -ablauf (17, 18).

9. Roller according to one of claims 1 to 8, characterized in that at least one chamber (8, 9) via a channel (10) is supplied, in which there is a throttle.

10. Roller according to one of claims 4 to 9, characterized in that on or in the roller (1) has a sensor arrangement (19) is mounted, which is in communication with a control device (22), the at least one actuator (1 1 ).

1 1. Roller according to one of claims 5 to 10, characterized in that the pressure exerted by the actuator (1 1) via the diaphragm (12) to the pressurized fluid of a chamber (8, 9) in operation at a frequency of 100 to 400 Hz.

12. A method for preventing vibrations on a roller according to claim 1, characterized in that the volume of a chamber (8, 9) is changed pulsating.

13. The method according to claim 13, characterized in that to activate the vibration prevention, the pressure in the chamber (8, 9) is changed.

14. The method according to claim 12 or 13, characterized in that the expansion of the chamber volume changing means (2) is controlled on the basis of vibration measurements.