EP1348807B1 - Method of operating a papermaking machine and papermaking machine - Google Patents

Abstract

A paper-processing machine has two cylinders (12, 14) forming a nip gap through which a paper web feeds continually. The nip gap (16) is esp. monitored by a sound emitter and detector (18) in air close to an elastic cylinder (12). The sound detector (18) is located in the immediate vicinity of the gap and operates on a continuous, semi-continuous or intermittent basis. The detector is coupled to a measurement and control unit (22) which gives a warning when the sound passes a pre-determined threshold linked to the barring effect associated with the onset of faulty paper quality. The measurement and control unit is further linked to a cooling water supply to the cylinder.

Description

The invention relates to a method for operating a paper machine, in which vibrations which occur on at least one roller and / or on at least one nip formed between a roller and a mating surface, in particular a mating roller, are monitored. It further relates to a corresponding paper machine.

Methods and paper machines of the aforementioned type are described in WO99 / 20836 and in EP 0 779 394 A1.

For example, in calenders, calenders, coating units, in particular size presses, and / or the like, it can come in particular in connection with the use of roll coverings to horizontal stripes on the paper web. Once these streaks become visible, the paper web is unusable and forms rejects. This so-called barring effect is probably due to the effects of vibes.

W001150030 discloses a method of reducing vibration in gaps formed by pairs of rolls, such as press nips or calendering nips. According to D1, the oscillations can be made without contact by means of ultrasound technology, i. be measured by a transit time measurement of an emitted from an ultrasonic sensor and detected by an ultrasonic sensor ultrasonic signal.

From the publication of Y.N. Chen et al. TAPPI, Atlanta, US, Bd58, No. 8, August 1975, pages 147-151, XP002216957 discloses a method for reducing the barring effect, in which the. Barring effect on paper Rolling a roll stack are offset when vibrations occur to each other in the machine direction.

WO00 / 09805 shows a method of changing the natural vibration frequency of a paper machine roll to prevent an occurrence of resonance vibrations.

The aim of the invention is to provide an improved method and an improved paper machine of the type mentioned above, with which a simple way of early detection of the Barring effect, ripples in the roll cover and / or similar phenomena is possible to appropriate if appropriate Initiate countermeasures.

This object is achieved according to the invention by a method for operating a paper machine, wherein the vibrations on at least one roller and / or at least one between a roller and a nip formed by a mating surface, in particular counter-roller, are monitored by a sound measurement carried out in the region of the roller or in the region of the nip, the airborne sound produced by the vibrations being measured during the sound measurement.

Due to this configuration, the barring effect can be recognized at a very early stage, so that it is now possible to initiate timely countermeasures. As a result, especially longer service life is achieved.

The sound is advantageously carried out in the immediate vicinity of the roller or the nip.

The sound measurement can be repeatedly performed and / or analyzed, wherein preferably a periodic sound measurement or analysis is provided. In principle, however, a continuous sound measurement and / or analysis is possible.

For example, a respective sound level measurement or sound intensity measurement can take place.

Advantageously, the sound measurement is carried out by means of at least one sound sensor, in particular a sound pressure sensor, in particular a microphone.

A preferred practical embodiment of the method according to the invention is characterized in that an obtained sound measurement value or a value derived therefrom with a predeterminable upper limit vibration counteract or reduce the vibrations to a minimum.

Advantageously, the sound measurement is carried out in the region of at least one roller inclined to a barring effect or in the region of at least one nip inclined toward such a barring effect. In this case, the sound measurement can be carried out in particular in the region of at least one roller provided with a cover and / or in the region of at least one elastic roller.

The sound measurement can take place, for example, in the region of a calender, a calender, a size press, a guide roll and / or the like.

A respective sound measurement can be carried out, for example, in the region of the jacket of the respective roll, in the region of a roll support and / or in the region of a roll end face.

The vibrations detected in the manner described can be counteracted by different actuators or measures.

According to a preferred practical embodiment of the method according to the invention, the vibrations are counteracted by means of a corresponding roller displacement in the axial direction and / or in the machine direction. Such a measure is particularly advantageous in the case of a calender. Preferably, a roll offset occurs in the machine direction.

According to a further advantageous embodiment, the vibrations are counteracted via a corresponding control and / or regulation of the rigidity and / or the damping of an active roller bearing. It can, for example Such an active roll bearing can be used, as described in DE 100 19 506 A1.

In certain cases, it is also advantageous to counteract the vibrations via a corresponding control and / or regulation of the roll and / or roll lining temperature. In this case, for example, a corresponding control and / or regulation of the cooling water temperature or the cooling water effect can be provided.

In the case of a deflection-adjusting roller, the vibrations can be counteracted, for example, by means of a corresponding control and / or regulation of the damping of the hydraulic system of the inner support sources of the deflection-adjusting roller.

In the case of a size press, the vibrations can be counteracted, for example, by means of a corresponding control and / or regulation of the ink or glue temperature and / or the viscosity of the relevant paint or glue substance.

The resulting sound measurements are preferably subjected to frequency analysis. In particular, a so-called fast Fourier transformation comes into question.

In an expedient embodiment, the entire spectrum is measured or taken into account in the sound measurement and / or in the sound analysis.

In another preferred practical embodiment of the method according to the invention, only at least one predeterminable frequency band is measured or taken into account in the sound measurement and / or in the sound analysis.

In another preferred practical embodiment of the method according to the invention, only at least one predeterminable frequency band is measured or taken into account in the sound measurement and / or in the sound analysis.

According to a further preferred practical embodiment of the method according to the invention, the sound measurement is carried out for at least one predeterminable frequency and / or at least one sound measurement value obtained for a predefinable frequency is compared with a predefinable upper limit value. In this case, for example, at least one previously determinable barring frequency can be taken into account.

The above-mentioned object is further achieved by a paper machine having a device for monitoring vibrations that occur on at least one roller and / or on at least one nip formed between a roller and a mating surface, in particular a mating roller, wherein the monitoring device comprises a sound measuring device, via which a sound measurement is carried out in the region of the roller or in the region of the nip, wherein the device for monitoring the vibrations is designed to measure the airborne sound generated by the vibrations.

Preferred embodiments of the paper machine according to the invention are specified in the subclaims.

Figur 1

eine schematische Darstellung einer Einrichtung zur Überwachung von Schwingungen, die an einer z.B. in einer Papierma-

Figur 3

eine schematische Darstellung einer Walzenanordnung mit zugeordnetem Schallsensor, der im Bereich einer Walzenstimseite angeordnet ist, und

Figur 4

eine schematische Darstellung der Umwandlung eines Schallmesssignals aus dem Zeitbereich in den Frequenzbereich mittels einer Fast-Fourrier- Transformation.

The invention is explained in more detail below with reference to embodiments with reference to the drawing; in this show:

FIG. 1

1 is a schematic representation of a device for monitoring vibrations that occur at an example in a Papierma-

FIG. 3

a schematic representation of a roller assembly with associated sound sensor, which is arranged in the region of a Walzenstimseite, and

FIG. 4

a schematic representation of the conversion of a sound measurement signal from the time domain in the frequency domain by means of a fast Fourier transform.

1 shows a schematic representation of a device 10 for monitoring vibrations which may occur on at least one roller and / or on at least one nip formed between a roller and a mating surface, in particular a mating roller. In the figure 1, for example, a two rollers 12, 14 comprehensive, a nip 16 forming roller assembly is shown, which may be provided in particular in a paper machine.

The monitoring device 10 comprises at least one sound sensor 18, which in particular is a sound pressure sensor, e.g. Microphone, can act.

The roller 12 is, for example, a roller that tends to a barring effect. In the present case, the sound sensor 18 is arranged in the immediate vicinity of the jacket 12 'of this roller 12.

The sound sensor 18 is part of an integrated, for example, in the monitoring device 10 sound measuring device 20. In the present case, the sound measuring device 20 and the sound sensor 18 is designed for airborne sound measurement.

The monitoring or sound measuring device 10, 20 may in particular be designed so that the sound measurement and / or analysis is repeatedly carried out. In this case, preferably a periodic sound measurement or sound analysis intended. The sound measurement or sound analysis can, however, basically also be continuous.

For example, the sound level and / or the sound intensity can be measured via the sound sensor 18.

The monitoring device 10 may in particular include a control and / or regulating device 22. In particular, at least one control circuit or control circuit for active and / or passive measures can be provided in the monitoring system 10.

The monitoring system 10 including the control and / or regulating device 22 may in particular be designed such that a respective received sound measurement value or a value derived therefrom is compared with a predefinable upper limit value and if this limit value is exceeded the limit value is exceeded and / or control and / or or control steps are activated, which counteract the oscillations or reduce the vibrations to a minimum.

The roller 12 may for example be provided with a coating and / or be formed by an elastic roller.
The sound measurement can take place, for example, in the area of a calender, a calender, a size press and / or the like. It can for example also be made on a guide roller.

FIG. 2 shows, in a schematic representation, again a roller arrangement with two rollers 12, 14, between which a nip 16 is formed. In the present case, however, the sound sensor 18 is arranged in the region of a roller bearing 24. In this case, the sound sensor 18 may be provided, for example, in the immediate vicinity of a roller bearing 24 of the upper roller 12.

The sound sensor 18 may in particular again be a sound pressure sensor, e.g. Microphone, act.

Moreover, the monitoring device can in particular be designed again as described in connection with FIG.

FIG. 3 shows, in a schematic illustration, a roller arrangement comprising, for example, four rollers 26 - 32. In the present case, a sound sensor 18 in the immediate vicinity of an end face 34 is e.g. the second roller 28 is arranged from above.

In the present case, too, the sound sensor 18 may again be a sound pressure sensor, e.g. Microphone, act. As with the other embodiments, in principle, for example, a sound level measurement or a sound intensity measurement is conceivable.

Moreover, the monitoring device 10 may in particular be designed again as described in connection with FIG.

FIG. 4 shows a schematic representation of the conversion of a sound measurement signal 36 from the time domain (left-hand part of FIG. 4) into the frequency domain (right-hand part of FIG. 4) by means of a fast Fourier transformation (FFT).

In the left part of Figure 4, the time course of the resulting sound measurement signal, z. As the sound pressure, over time. The values can be specified, for example, in "dB" or in "Pa".

By means of the fast Fourier transformation (FFT), this sound measurement signal 36 is transmitted in the frequency domain (compare the right-hand part of FIG. By doing The relevant diagram in the right part of FIG. 4 plots the amplitude versus frequency. The amplitudes may, for example, be given in "dB" or "Pa".

The amplitudes obtained in the frequency range for the various frequencies v _i are each compared with a predeterminable upper limit value 38 in order to be able to initiate active and / or passive measures if this limit value 38 is exceeded. In the present case, the limit value 38 is exceeded by the amplitudes at the frequencies v ₁ and v ₂ . Insofar as, for example, these should be critical frequencies with regard to the above-mentioned barring effect, the measures in question must be initiated. Exceeding the limit value 38 can be an indication, for example, that the rolls become out of round. The respective vibrations can then be counteracted, for example, by a corresponding roller offset.

LIST OF REFERENCE NUMBERS

10

monitoring device

12

roller

14

roller

16

nip

18

sound sensor

20

Sound measurement device

22

Control and / or regulating device

24

roller bearings

26

roller

28

roller

30

roller

32

roller

34

front

36

Sound measurement signal

38

limit

Claims (50)

1. Method of operating a paper machine, in which oscillations which occur at at least one roll (12, 28) and/or at at least one nip (16) formed between a roll (12) and an opposing surface, in particular a backing roll (14), are monitored by a sound measurement carried out in the region of the roll (12, 28) or in the region of the nip (16), characterized in that, during the sound measurement, the airborne sound generated by the oscillations is measured.
2. Method according to Claim 1, characterized in that the sound measurement is carried out in the immediate vicinity of the roll (12, 28) or of the nip (16).
3. Method according to one of the preceding claims, characterized in that the sound measurement is carried out and/or analyzed repeatedly.
4. Method according to Claim 3, characterized in that the sound measurement is carried out and/or analyzed periodically.
5. Method according to one of Claims 1 to 3, characterized in that the sound measurement is carried out and/or analyzed continuously.
6. Method according to one of the preceding claims, characterized in that a sound level measurement is carried out in each case.
7. Method according to one of the preceding claims, characterized in that a sound intensity measurement is carried out in each case.
8. Method according to one of the preceding claims, characterized in that the sound measurement is carried out by means of at least one sound sensor (18), in particular a sound pressure sensor, in particular a microphone.
9. Method according to one of the preceding claims, characterized in that a measured sound value that is obtained is compared with a predefinable upper limiting value (38) and, if this limiting value (38) is exceeded, the fact that the limiting value has been exceeded is signalled and/or control and/or regulation steps are activated which counteract the oscillations or reduce the oscillations to a minimum.
10. Method according to one of the preceding claims, characterized in that the sound measurement is carried out in the region of at least one roll (12, 28) that tends to produce a barring effect or in the region of at least one nip (16) that tends to produce such a barring effect.
11. Method according to Claim 10, characterized in that the sound measurement is carried out in the region of at least one roll provided with a cover and/or in the region of at least one resilient roll (12).
12. Method according to one of the preceding claims, characterized in that the sound measurement is carried out in the region of a calender, a smoothing unit, a size press, a guide roll and/or the like.
13. Method according to one of the preceding claims, characterized in that the sound measurement is carried out in the region of a roll shell (12').
14. Method according to one of the preceding claims, characterized in that the sound measurement is carried out in the region of a roll mounting (24).
15. Method according to one of the preceding claims, characterized in that the sound measurement is carried out in the region of an end (34) of a roll.
16. Method according to one of the preceding claims, characterized in that the oscillations are counteracted via an appropriate roll offset in the axial direction and/or in the machine running direction.
17. Method according to one of the preceding claims, characterized in that the oscillations are counteracted via appropriate control and/or regulation of the stiffness and/or the damping of an active roll mounting.
18. Method according to one of the preceding claims, characterized in that the oscillations are counteracted via appropriate control and/or regulation of the roll temperature and/or roll cover temperature.
19. Method according to Claim 18, characterized in that the oscillations are counteracted via appropriate control and/or regulation of the cooling-water temperature.
20. Method according to one of the preceding claims, characterized in that, in the case of a controlled deflection roll, the oscillations are counteracted via appropriate control and/or regulation of the damping of the hydraulic system of the inner supporting sources of the controlled deflection roll.
21. Method according to one of the preceding claims, characterized in that, in the case of a size press, the oscillations are counteracted via appropriate control and/or regulation of the temperature of the colour or size and/or of the viscosity of the relevant colour or size.
22. Method according to one of the preceding claims, characterized in that the measured sound values obtained are subjected to a frequency analysis.
23. Method according to one of the preceding claims, characterized in that, during the sound measurement and/or during the sound analysis, the entire spectrum is measured and taken into account.
24. Method according to one of the preceding claims, characterized in that, during the sound measurement and/or during the sound analysis, only at least one predefinable frequency band is measured and taken into account.
25. Method according to one of the preceding claims, characterized in that the sound measurement is carried out for at least one predefinable frequency and/or at least one measured sound value obtained for a predefinable frequency is compared with a predefinable upper limiting value (38).
26. Paper machine having a device (10) for monitoring oscillations which occur at at least one roll (12, 28) and/or at at least one nip (16) formed between a roll (12) and an opposing surface, in particular a backing roll (14), the monitoring device (10) comprising a sound measuring device, via which a sound measurement can be carried out in the region of the roll (12, 28) or in the region of the nip (16), characterized in that the device (10) for monitoring the oscillation is designed to measure the airborne sound generated by the oscillations.
27. Paper machine according to Claim 26, characterized in that the sound measuring device (20) is designed for a sound measurement in the immediate vicinity of the roll (12, 28) or of the nip (16).
28. Paper machine according to either of Claims 26 and 27, characterized in that the monitoring or sound measuring device (10, 20) is designed in such a way that the sound measurement can be carried out and/or analyzed repeatedly.
29. Paper machine according to Claim 28, characterized in that the monitoring or sound measuring device (10, 20) is designed in such a way that the sound measurement can be carried out and/or analyzed periodically.
30. Paper machine according to either of Claims 26 and 27, characterized in that the monitoring or sound measuring device (10, 20) is designed in such a way that the sound measurement can be carried out and/or analyzed continuously.
31. Paper machine according to one of Claims 26 to 30, characterized in that the sound measuring device (20) comprises means (18) for a respective sound level measurement.
32. Paper machine according to one of Claims 26 to 31, characterized in that the sound measuring device (20) comprises means (18) for a respective sound intensity measurement.
33. Paper machine according to one of Claims 26 to 32, characterized in that the sound measuring device (20) comprises at least one sound sensor (18), in particular a sound pressure sensor, in particular a microphone.
34. Paper machine according to one of Claims 26 to 33, characterized in that the monitoring device (10) comprises a control and/or regulating device (22) in order to compare a respective measured sound value obtained with a predefinable upper limiting value (38) and, if this limiting value (38) is exceeded, to signal the fact that the limiting value has been exceeded and/or to activate control and/or regulation steps which counteract the oscillations or reduce the oscillations to a minimum.
35. Paper machine according to one of Claims 26 to 34, characterized in that the sound measurement is carried out in the region of at least one roll (12, 28) that tends to produce a barring effect or in the region of at least one nip (16) that tends to produce such a barring effect.
36. Paper machine according to Claim 35, characterized in that the sound measurement is carried out in the region of at least one roll provided with a cover and/or in the region of at least one resilient roll (12).
37. Paper machine according to one of Claims 26 to 36, characterized in that the sound measurement is carried out in the region of a calender, a smoothing unit, a size press, a guide roll and/or the like.
38. Paper machine according to one of Claims 26 to 37, characterized in that the sound measurement is carried out in the region of a roll shell (12').
39. Paper machine according to one of Claims 26 to 38, characterized in that the sound measurement is carried out in the region of a roll mounting (24).
40. Paper machine according to one of Claims 26 to 39, characterized in that the sound measurement is carried out in the region of an end (34) of a roll.
41. Paper machine according to one of Claims 26 to 40, characterized in that the monitoring device (10) comprises means (22) in order to counteract the oscillations via an appropriate roll offset in the axial direction and/or in the machine running direction.
42. Paper machine according to one of Claims 26 to 41, characterized in that the monitoring device (10) comprises means (22) in order to counteract the oscillations via appropriate control and/or regulation of the stiffness and/or the damping of an active roll mounting (24).
43. Paper machine according to one of Claims 26 to 42, characterized in that the monitoring device (10) comprises means (22) in order to counteract the oscillations via appropriate control and/or regulation of the roll temperature and/or roll cover temperature.
44. Paper machine according to Claim 43, characterized in that the monitoring device (10) comprises means (22) in order to counteract the oscillations via appropriate control and/or regulation of the cooling-water temperature.
45. Paper machine according to one of Claims 26 to 44, characterized in that the monitoring device (10) comprises means (22) in order, in the case of a controlled deflection roll, to counteract the oscillations via appropriate control and/or regulation of the damping of the hydraulic system of the inner supporting sources of the controlled deflection roll.
46. Paper machine according to one of Claims 26 to 45, characterized in that the monitoring device (10) comprises means (22) in order, in the case of a size press, to counteract the oscillations via appropriate control and/or regulation of the temperature of the colour or size and/or the viscosity of the relevant colour or size.
47. Paper machine according to one of Claims 26 to 46, characterized in that the monitoring device (10) comprises means (22) in order to subject the measured sound values obtained to a frequency analysis.
48. Paper machine according to one of Claims 26 to 47, characterized in that, during the sound measurement, the entire spectrum is measured and is taken into account during the analysis.
49. Paper machine according to one of Claims 26 to 48, characterized in that, during the sound measurement, predefinable frequency bands are measured and are taken into account during the analysis.
50. Paper machine according to one of Claims 26 to 49, characterized in that the sound measurement is carried out for at least one predefinable frequency and the measured value obtained for such a frequency is compared with a predefinable upper limiting value (38).

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