FI118268B - Calendar and method of calendaring - Google Patents

Description

Calendar and Calendering Methods 1 1 8268

The present invention relates to a calender comprising at least one roll and at least I

means one member for pressing a paper or cardboard web against a roll. The invention also relates to a method for removing impurities from the caliper roll surface.

The invention relates to the manufacture of paper and board webs. The production of paper or cardboard web starts from the headbox. In the headbox, the web is formed by spraying 10 water-rich pulp between two wires. In addition to water and fibers, the pulp may contain many other substances, for example, mineral fillers. From the Pe box, the web is taken to a press section where the pulp is dewatered and a solid web begins to form. The web is passed through a press section between two opposing felts. After the press section, the web is applied to a dryer section where the web is dried by heating. The dry part comprises heated drying cylinders on whose surface the web is transported supported by a wire or felt. After drying, the web is taken to a finishing section of a paper or board machine where the web is coated and / or calendered. Post-processing can be done with devices integrated directly into the paper machine, resulting in the same machine speed as the paper machine, or • 1 · I, · 20 separate devices. When using separate off-line finishing equipment, the finishing "• 1 *] equipment, such as calendars and coaters, usually has more than one paper · · · 1 •« ... per machine. In this case, the paper is rolled and processed prior to finishing | • · Post-processing equipment, in the order specified by production capacity and orders.

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Calendering improves the gloss and smoothness of the web and increases the density of the web.

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The press and dry portion may adhere to the felt hairs, which are calendered.

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\.! # sticks to the calender roller diaper surfaces. Felt hairs are particularly adhered to • 1 ”1 30 rolls with a soft-coated surface. The felt hairs on the roll surface, on the other hand, press into the calendering web nip holes that appear on the printed paper or board as non-printed points. The problem is particularly acute in the gravure printing process. Felt hairs can be removed from the surface of the roller by a mechanical scraper, but there is a risk that the soft coating of the roller may be worn or otherwise damaged.

EP 0 775 777 discloses a calender in which 5 roller-resistant plastic rollers are used as soft rollers and these rollers are cleaned with a scraper blade. The method of carrying out the scraping is not explained in detail.

The object of the present invention is to provide a solution by which felt hairs and other impurities such as filler and unbound fibrous material can be removed from the calender roll shell surface without damaging the roll.

The invention is based on the provision of a cleaning device in connection with the calender, by which the impurities on the roll surface are removed by means of a tractive force applied thereto. The traction force is obtained, for example, by means of an adhesive on the cleaning device or an electrically charged collection surface and / or suction.

More specifically, the calender of the invention is characterized by what is set forth in the characterizing part of claim 1.

The process according to the invention is in turn characterized by what is described. ie in the characterizing part of claim 7.

«*» ··· • · * · • * · •. ·. The invention provides considerable advantages.

In the invention, felt hairs and other impurities on the surface of the calender roll are • removed by means of a tractive force applied thereto, which prevents damage to the roll mantle surface. This extends the interval between calender rolls and reduces the number of indentations on the calendered web. In addition, press and drying section • * * *, · **. the intervals between the used felts are longer, since they do not have to be replaced due to the removal of the felt hairs. The cleaning device according to the invention is also simple in structure and can be easily installed in connection with existing calendars.

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118268!

The invention will now be described in more detail by the examples set forth in the accompanying drawings. .

Figures la to la show different types of calendars viewed from the side.

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Figure 2 is a side elevational view of one embodiment of the invention.

Figure 3 is a side elevational view of another embodiment of the invention.

Fig. 4 is a side elevational view of a third embodiment of the invention.

In the following, a calender refers to a multi-roll, long nip, belt or metal belt calender.

The multi-roll calender shown in Figure 1a comprises a roll stack mounted on the calender body having a deflection compensated top roll 23 and a deflection compensated lower roll 24 and intermediate rolls 25-32 arranged between the top and bottom roll. There are two or more intermediate rollers. The rolls of the roll stack are arranged such that the overlapping rolls form nipples through which the calenderable web 21 is passed. The web 21 is first directed to the nip formed by the upper roller 23 and i i · A · * 20 formed by the upper intermediate roll 25, and further through the other nips to the lower nip N9 formed by the lower roll 24 and the lower intermediate roll 32. Between nipples N1-N9 • · ..., the web 21 is removed from the surface of the rolls by the take-up rolls 22. Deflection-compensated rolls adjust the transverse thickness and gloss profile of the web.

. ···] There are hydraulic loading elements inside the deflection compensated rollers which influence the inner surface of the roll casing. The load elements are supported on the roll shaft.

! *. The loading element comprises a sliding shoe fitted against the inside surface of the roll shell and a pressure chamber having a pressure medium. The pressure medium pressures the sliding shoe ··· against the inside surface of the roll diaper. By adjusting the pressure of the pressure medium, the deflection of the roll casing •, ···, and thus the nip load can be profiled in the web width direction. Pressurized • · 30i · 30 fluid pressure is controlled by the control system. The pressure medium used is, for example, hydraulic oil,.

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The shaft of the upper roller 23 is mounted at both ends in the bearing housings 33, which are slidably attached to the vertical guides 35 mounted on the calender body 34. The bearing housings 33 of the upper roll 23 may be displaced vertically along the rails 35 by the loading cylinders 36.

The shaft of the lower roll 24 is mounted at both ends in bearing housings 37 which are slidably secured to vertical guides 10 mounted on the calender body 34. Each bearing housing 37 of the lower roller 24 has a loading cylinder 38 attached to the calender body 34, by means of which the lower roller 24 can be moved vertically.

The spacer rollers 25-32 are of either hard surface thermo rolls or rolls with a soft coating, preferably a polymer coating. The intermediate rolls 25-32 are arranged in a roll stack such that at least one of the rolls of each nip is provided with a soft coating. Typically, rolls with a soft coating will have a coating of polymer or fibrous material such as paper. In the turning nip N5, both rolls 28, 29 forming the nip "n" are provided with a soft coating. The shafts of the intermediate rollers 25-32 • * • · I, * 20 are rotatably mounted at both ends in the bearing housings 39. In the bearing housings * * * * #. 39 are provided with base members 40 which are pivotally mounted on the calender body 41 • ♦ 34. The base members 40 are provided with lightening means 20 for causing mass of intermediate rolls. ; 4. the nipple load can be reduced. In the calender of Figure 1, lightening devices • * ·. ···. the first end of the lightening cylinder 20 is attached to the base 40 and the other end to the calender body 34. For example, the hydraulic fluid or: "* · compressed air is used as the pressure medium for the pressure cylinder.

• · · • · • · • * ·. ···. The relief cylinders 20 are used to provide the relief rolls to the base portions 40 of the intermediate rollers 25-32. *. 30 to compensate, in whole or in part, for the weight of the nip caused by the weight of the intermediate rollers 25-32 and the auxiliaries attached to them.

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The felt used on the press and / or dry part of the paper or board machine »picks off hair which is carried along the web to the calender. From the surface of the web, the felt hairs continue to migrate to the diaper surfaces of the calender rolls. In particular, the felt hair accumulates on the surface of the lowest draw roll (i.e., the roll with the drive) 5 in the roll stack. In addition, felt hairs accumulate especially on the surfaces of rolls with a soft coating (polymer or fiber coating). As previously stated, the felt hairs on the roll surfaces cause indentations on the calendered web which weaken the print.

Figure Ib shows one nip of a soft calender. It has a soft roller 31 at the top.

This roll is made of a polymeric material mounted on a metal body. With the soft roll, the nip is formed by a hard metal roll 32 made of metal, which can be heated, for example, with oil. Figure le shows a long nipple lantern. Here, one of the rolls is replaced by a shoe 33 'and a sheath running around the shoe 33'. The sheath 34 'is pressed with the shoe 33' against the counter roll to provide a long nip.

Figures 2-4 show cleaning devices 1, 3, 6 for removing impurities, in particular felt hairs, from the shell surfaces of the calender rollers. The cleaning devices • · * * * *: · '20 apply a tensile force to the impurity particle on the roll surface to remove the particle from the roll. In the embodiments shown in Figures 2-4, the particle release tensile force is provided by an adhesive surface adhering to the particle. or by electrical charge or suction, or a combination of the two., The cleaning devices 1, 3, 6 are used to remove impurities, particularly from the surfaces of rolls with a soft coating (polymer or fiber coating).

; · # Preferably, impurities are removed with the lowest soft coating on the calender • · · *> ^ ...

, ···. 1, on the surface of the lower intermediate roller 31, for example in the calender of Figure 1. Of course, the cleaning device 1, 3, 6 can also be used to remove impurities from the mantle surfaces of the other rolls of the calender.

• · • * * Γ 30 In the offline calender, the roll is cleaned, for example, when changing the reel, * • · · M · * for low calender roll speeds. In the online calender, the roller blades * · '', for example, during a web break or other shutdown.

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In the embodiment of Figure 2, the cleaning device 1 comprises a rotatable cleaning roll 9 having a central axis parallel to the kcs of the roll to be cleaned. ~ with the axle. The cylindrical sheath surface of the cleaning roll 9 is partially or completely enclosed by a coating layer 2 whose outer surface, i.e. the surface to be fitted against the sheath surface of the roll 31 to be cleaned, is sticky. The adhesive outer surface of the coating layer 2 is formed, for example, by applying a suitable adhesive to the outer surface 2 of the coating layer 2. The cleaning roll 9 is mounted, for example, in connection with a service level in front of the calender roll stack. The treatment platform is movable vertically. The cleaning device 1 is movable horizontally both along the axis 31 (transverse direction) of the roll 10 to be cleaned and perpendicular to the axis of the roll being cleaned (machine direction).

At the start of cleaning, the treatment platform is moved to a suitable height in front of the roll 31 to be cleaned, after which the sheath surface of the cleaning roll 9 is moved into contact with the surface of the roll 31 to be cleaned. The roll 31 to be cleaned is rotated, whereby the cleaning roll 9 also rotates. The adhesive coating 2 of the cleaning roll 9 adheres to and pulls off impurities on the roll surface of the roll 31. If the cleaning roller 2 is narrower than the roller 31 to be cleaned, the cleaning roller 2 is displaced in a transverse direction so that the sheath surface of the roller 31 to be cleaned is machined with a width of about 20 cm. In order to improve the cleaning result, the cleaning roll 2 may be oscillated, i.e. displaced transversely back and forth on the surface of the roll 31 to be cleaned.

* · * * T * Similar processing can be performed on other calender rolls. After cleaning, the felt cloths adhering to the adhesive coating 2 of the cleaning roll 9 ♦ · ... and other impurities are removed, for example, by washing or 9 m «• · 25 of the cleaning roll is replaced with a new adhesive coating.

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In the embodiment of Fig. 3, the cleaning device 3 comprises pulleys 4 which •. An endless belt 5 is fitted around the outer surfaces of the belt 5, i.e., against the cleaning. * * ··· ·. * ··. The rollable surface 31 of the roller 31 is adhesive. The adhesive outer surface of the belt 5 is. 30 formed, for example, by applying to the outer surface of the belt 5 a suitable adhesive. The cleaning device 3 is mounted, for example, in connection with the treatment platform in front of the calender roll stack. The treatment platform is movable vertically. The cleaning device 3, 118268 is movable horizontally both parallel to the axis of the roll to be cleaned and perpendicular to the axis of the roll to be cleaned.

At the start of the cleaning, the treatment platform is moved to a suitable height in front of the roll 5 to be cleaned, after which the outer surface of the belt 5 of the cleaning device 3 is moved into contact with the diaper surface of the roll 31 to be cleaned. The roll 31 to be cleaned is rotated, whereby the belt 5 rotates about the pulleys 4. The adhesive outer surface of the belt 5 adheres to felt felts or other impurities on the roll surface of the roll and pulls them away from the roll surface 31 of the roll. If the adhesive surface of the belt 5 is thinner than the roll 31 to be cleaned, the cleaning device is moved transversely to clean the shell surface of the roll 31 across its entire width. In order to improve the cleaning result, the cleaning device 3 can be oscillated, i.e. moved transversely back and forth on the surface of the roll 31 to be cleaned. A similar treatment can also be performed on other calender rolls. After cleaning, the felt hairs and other impurities adhering to the adhesive surface of the belt 5 are removed, for example, by washing, or a new belt is replaced with the cleaning device 3.

In the embodiment of Figure 4, the cleaning device 6 comprises a beam 10 having a scraper adapted to be fitted against the shell surface of the roll 31 to be cleaned. As a scraper, a rotary 20 scraper rod 7 is used. In the embodiment of Fig. 4, there are two scraper rods 7 and a nozzle 8 is provided adjacent, line and / or adjacent to the surface of the roll 31 of air to be cleaned. Alternatively, the nozzle 8 may be provided with a suction. Like the picture • · • ·· *. In the embodiments 2 and 3, the cleaning device 6 is mounted, for example, in connection with a treatment platform in front of a k ante ······· · ·. The treatment platform can be moved vertically • · 25. The cleaning device 6 is movable horizontally both parallel to the axis of the roll to be cleaned and · perpendicular to the axis of the roll to be cleaned.

• * ···; As the cleaning begins, the scraper of the cleaning device 6 is moved against the sheath of the roller 31 • · · ···. the surface. The roller 31 is rotated, whereby the scraper 7 removes the felt hairs and other impurities present on the roller surface of the roller 31. The air blown from the nozzle 8 increases the cleaning effect and moves the loose impurities further away from the roll shell.

If the nozzle 8 is provided with a suction, the felt hairs on the sheath surface of the roll 31 and the other impurities will be removed by the suction and transported to the angry 8. Similarly, the diaper surfaces of other calender rollers may be cleaned in a similar manner.

The invention has embodiments different from those described above.

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Impurities on the sheath surface of the roller 31 can be removed by electrical traction. In this case, the cleaning device has a collecting surface made of electrically conductive material, to which a high voltage is applied from a voltage source connected to the collecting surface. The collection surface is brought in proximity to the sheath surface of the roll to be cleaned or Koskelo with the sheath surface, whereby impurities on the sheath surface are removed from the roll and transferred to the collection surface by electrical traction. The cleaning devices according to the invention can be used in other types of calendars, for example in a conventional multi-nip calender, in which the nip pile load due to the mass of the rolls is not reduced by the lightening devices. Of course, the invention can also be used in a multi-roll, soft, long-nip, belt or metal belt calender.

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Claims (7)

A calender for calendering a movable paper or cardboard web (21), the calender comprising at least one roller (31) and a second member (32) arranged in the nip contact, the web (21) for calendering being arranged to passing through the nip (Ng) between the roller (31) and the second member (32), and a cleaning device (1, 3,6) for removing impurities on the surface of the roller (31), said cleaning device (1,3,6) ) comprises means (2, 5, 8) for providing a pulling force directed against a contaminant particle, characterized in that the means for producing the pulling force comprise an adhesive joint surface (2, 5) which can be arranged in contact with the cleaning means. rollers (31). Calender according to claim 1, characterized in that the cleaning device (1) comprises a roller (9), the sheath of which is surrounded by the adhesive collecting surface (2). Calender according to claim 1, characterized in that the cleaning device (3) comprises pulleys (4), around which a band (5) is provided, the outer surface of which is adhesive. t · · • · · * '20 4. Calendar according to claim 1, characterized in that the means for providing the pulling force further comprise an assembly surface which can be electrically charged. • »• M * * ·· • ·. **! 5. Calendar according to claim 1, characterized in that the means for providing I ·! the pulling force further comprises a nozzle arranged at the cleaning device (6) for forming suction from the device in the nozzle. * · * · • ··. · **. A method for removing contaminants from a surface of a calender roll (31), whereby a contaminant particle located on the surface of the roll (31) is directed to a pulling force which dissolves the particle from the surface of the roll (31), characterized in that the pulling force is formed with an adhesive surface (2, 5) arranged in contact with the roller (31) for cleaning. * • • I 118268 n 7. A method according to claim 6, characterized in that the drawing force is also generated by electric charge. • ft · ··· • · • · ·· * * »M • · ··« '• ft • ft ··· • * ft • · ft ft · ft · • ♦ ft ft · • ft ft ft ft • ft ft ft • ·· ft ft ft ft • · * ft ··· ft ft ft ft ft ft ftft • • ft ft • ft • ft • ft ft ft • ft • · ft • ft ft • •• ft ft ft ft '• ft • · • ft ft