FI115994B - attenuation - Google Patents

Description

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ATTENUATION

Background to the technology

The invention relates to paper machines and relates to the vibration damping of rolls. In particular, the invention can be used to dampen the vibration of rolls rotating against each other at high speed, for example in calendars.

10 Paper is made by rotating rollers through which the paper web is guided. Roller vibration can be a problem especially when trying to use ever higher speeds. Problems arise in particular with nip rolls, which are used, for example, in wet-pressing, coating, calendering and winding the paper web. Vibration shortens the roll life, increases energy consumption, causes 15 noise and reduces paper quality.

The nip may be in contact with a metal / polymer roll, a metal / paper roll, a metal / metal roll, a polymer / polymer roll, a metal roll / belt, etc. For example, various relatively soft coatings, such as plastics, may be used on the calender rolls. quickly. In this case, the coating may in particular be corrugated in the circumferential direction of the roll. Unevenness naturally transfers to the paper. The coating may also come off the roll. Particularly on calender rolls, oscillation itself can also cause unevenness in paper quality. Organic, ···. this requires increasingly precise roll manufacturing and especially balancing.

25 ;;; * Mechanical dampers, such as those located in the bearing housing, have been used to dampen vibrations, affecting the roll shaft support points.

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It has also been proposed to use hydraulic dampers inside the roll shell.

* · ♦ 30 One such apparatus is disclosed in U.S. Patent No. 5,487,715.

DESCRIPTION OF THE INVENTION '* · * * *; A method for attenuating the vibration of a roll used in paper making according to claim 1 has now been invented. Certain embodiments of the invention are set forth in the following claims.

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According to the invention, the damping means is applied radially from the outside of the roll casing by the damping member. In this way, the attenuation is applied to the desired position, especially to the point where the amplitude of the oscillation is greatest. Normally, the amplitude of the oscillation is greatest at the center of the roll.

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The damping member is preferably such that the damping can be adjusted. There may also be more than one suppressor.

The damping member may be in contact with or detached from the roll surface.

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In active damping, the roll is subjected to an external vibration damping force, for example, by means of a magnetic field or a fluid jet. In this case, the damping can be adjusted, in particular, by changing the damping force applied to the roll.

In passive damping, the vibration energy of a roll is removed by a damping member, such as a damping member pressed against the roll. The damping force then depends on the relative motion of the damping member and the contact point The damping member may be supported on its own support frame so that the damping is supported. Damping can be achieved, for example, by coulombic or viscous friction. In this case, the roll damping can be adjusted by changing the strut damping. The damping may also be in the body itself against the roll, whereby it may be, for example, a suitable resilient material such as a cleaning sponge. Damping ·: ·. in the sensor, the vibration energy of the roll is converted into heat. The damping member may · _. press against the roll with a radial rod or torsion arm.

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The cushioning may be applied only to a portion of the roll shell, particularly to the center thereof. In this case, the damping member may be one that can be displaced along the axis of the roll. The damping member may also be one that can be moved in the circumferential direction of the roll. The damping member may also be automatically moved to a particular program according to a particular program.

* In a system of two rotating rolls, the damping is best aligned with the plane passing through the axes of the rolls.

'· · · * 35 The roller has a device for measuring vibration. The damping is adjusted based on the measurement results:. When a movable damping member is used, it is then possible to mute; change the position of the body. Based on the measurement results, the damping properties can also be adjusted. The adjustment can be made automatic. The measurement may be based on, for example, ultrasound, laser or microwave technology. The measurement can monitor the amplitude, frequency or phase angle of the oscillation as a function of time.

At the same time, the mechanical damping member pressed against the roll can act as a roll cleaner. For example, it may have a sponge moistened with a cleaning liquid. A fluid jet, such as an air jet, can also act as a dampener and purifier.

The magnetic cleaning member need not touch the surface of the roll. It can also work through the paper web.

In particular, vibration damping can be used where there are rollers rotating against each other, such as wet pressing, coating, calendering and winding. For example, on a calendar, the oscillation frequencies can typically be in the range 100 to 1000 Hz. For example, in the coating nip, the frequencies may be 15 lower, up to about 50 Hz.

Some embodiments of the invention will now be described in detail. The accompanying drawing is part of the description. The figure schematically shows a calendar showing a vibration damping according to the invention.

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The calender shown in the figure has a lower roller 1 and an upper roller 2 mounted on the body, 'Γ; Above the upper roller is a transverse beam 3 parallel to the axis of the rolls, which is. : fixed at its ends to its support frame. Connected to the beam in the plane passing through the axes of the rollers is a carriage 4 movable in the axial direction. 25 is a diaphragm-directed shaft 5. At the lower end of the shaft is a damping member 6.

The shaft 5 must be adjusted so that the distance of the damping member 6 from the roller 2 can be changed.

:, ..: 30 The damping member 6 may be active, such as an electromagnet, for applying a · ** ': magnetic field to the roll.

... The damping member 6 may also be passive, such as a mechanical: against a roller: * a press. In this case, the support of the damping member has a strong damping through which the vibration of the roller becomes heat. To accomplish this, the arm 5 may, for example, be a hydraulic shock absorber.

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To the other side of the beam 3 is also mounted a transverse measuring device 7 for measuring the vibration of the roll, for example its amplitude. The measuring device is connected via the control system 8 to the control apparatus of the carriage 4 and the arm 5. Thus, the position of the damping member and the damping force 5 can be adjusted according to the signal provided by the measuring device.

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Claims (14)

11599'1 1. Förfarande för att dämpa vibrationen hos en Vals som används vid pappers-framställning, varvid valsen har et nmt hölje ä att valölöl utsätts för dämpning utanför hölök, kantetecknat av att vibrationegenskap mäts och dämpningen justeras. 20 A method of damping a vibration of a papermaking roll, the roll having a circular jacket, by applying a damping to the roll jacket from the outside of the jacket, characterized by measuring some vibration property and adjusting the damping based on the measurement results. 2. Förfarande enligt patentkrav 1, där höljet utsätts för Aktiv dämpning. . 3. Förfarande enligt patentkrav 1 eller 2, där höljet utsätts för passiv dämpning. ;;; "25 4. Förfarande enligt nagot av patentkrav 1 ... 3, därpningen riot mot valsens'; ·· * mitt.: 5. Förfarande enligt nagot av patentkrav 1 ... 4, därp vibrationens amplitud, ffek - vens eller fasvinkel m. ·: ·: 30 • '; 6. Förfarande enligt nagot av patentkrav 1 ... 5, där vibrationsegenskapen mä ut-. *. gäende frän ultraljuds-, laser-eller microlux. Förfarande enligt nagot av patentkrav 1 ... 6, där dämpningens verkningspunkt, •; ': 35 bars parallel to the valsaxeln, ändras i enlighet med mätresultaten. »» »♦ 11599'1 The method of claim 1, wherein the diaper is subjected to active damping. 10 The method of claim 1 or 2, wherein the diaper is subjected to passive damping. The method of any one of claims 1 to 3, wherein the damping 15 is applied to the center of the roll. The method of any one of claims 1 to 4, wherein the amplitude, frequency or phase angle of the oscillation is measured. The method of any one of claims 1 to 5, wherein the vibration property is measured based on ultrasonic, laser or microwave technology. The method according to any one of claims 1 to 6, wherein the point of effect of the damping, in particular along the axis of the roll, is altered according to the measurement results. * ;;; Apparatus for damping the vibration of a rotating roll (2) in a paper machine having a circular jacket and having a damping member (6) for exerting vibration damping on the outside of the roll (2), characterized in that means (7) for measuring a characteristic of the oscillation and means: •: * ·: (8, 4, 5) for adjusting the damping based on the measurement results. 8. Anläggning för att dämpa vibrationen hos en Vals (2) som roterar i en pappers-maskin, varvid valsen har et nmt hölje, och anläggningen innefattar et dämpnings-organ (6) för att riot vibrationsdämpningen mot valsens (2) hölje utifrän, tilt-tecknad av att anläggningen har organ (7) för att rot en vibrationsegenskap och 5 organ (8, 4, 5) f att attera dämpningen utgäende frän mätresultaten. 9. Anläggning enligt patentkrav 8, därpningsorganet (6) gäller valsens (ref. 2). Apparatus according to claim 8, wherein the damping member (6) relates to a telescope. '; lan (2) surfaces. The apparatus of claim 8, wherein the damping member (6) is off the surface of the roll: '": (2). 10. Anläggning enligt patentkrav 8, dämpningsorganet (6), inte grenbering med valsens (2). 11. Anläggning enligt face of the patent kraven 8-10, därpningsorganet (6) rörligt, exempelvis parallellt med valsaxeln. 15 Apparatus according to any one of claims 8 to 10, wherein the damping member (6) is movable, for example in the direction of the roll axis. 12. Anläggning enligt nägot av patentkraven 8 ... 11, där dämpningsanläggningen har en valsrengörare. An apparatus according to any one of claims 8 to 11, wherein the damping apparatus comprises a roll cleaner. 13. Anläggning enligt patentkrav 9 and 12, där rengöraren är en svamp. 20 Apparatus according to claims 9 and 12, wherein the cleaner is a sponge. A paper web calender comprising two rolls (1, 2) and an apparatus for damping the vibration of at least one of the rolls (2), the apparatus having a damping member (6) for applying vibration damping to the outside of the roll (2), that the calender has means (7) for measuring one of the vibration characteristics and means (8, 4, 5) for adjusting the damping based on the measurement results. 15 14. Pappersbanekalander innefattande tvä valsar (1, 2) och en anläggning för att dämpa vibrationen hos ätminstone den ena valsen (2), varvid anläggningen har ·: ·. dämpningsorgan (6) för att rickshaw vibrationsdämpning mot valsens hölje (2) utifrän,. ·. : kännetecknad av att kalandem har organ (7) for att rot en vibrationsegenskap och / 25 organ (8, 4, 5) for att justera dämpningen utgäende frän mätresultaten. »T