FI122758B - Multi Roll Calender and Method in Multi Roll Calender - Google Patents

Description

Multi Roll Calender and Method in Multi Roll Calender Flervalskalander och forfarande i en flervalskalander

5 TECHNICAL FIELD

The invention relates to a multi-roll calender comprising a body and a support roll thereon, the track comprising a top roll and a lower roll, at least one of which is movably supported on the calender body, and intermediate rolls supported movably on the calender body.

The invention also relates to a method in a multi-roll calender comprising a body and a supported roller, the track comprising a top roll and a lower roll, at least one of which is movably supported on the calender body, and intermediate rolls supported 15 movably on the calender body.

BACKGROUND OF THE INVENTION

Calendering generally seeks to improve properties such as smoothness, gloss and oil adsorbability of a web material such as a paper or board web. In calendering, the web is guided to a nip formed between rolls to be pressed against each other, i.e. a calendering nip, in which the web is deformed by the action of temperature, humidity and nip pressure. In the calender, the nips are formed between a smooth-faced press roll, such as a metal roll, and a roll, coated with a flexible coating, such as a polymer roll. The flexible surface roll conforms to the surface of the web co modes and presses the opposing web evenly against the smooth-faced press roll speech x. In this context, calender rolls refer to the shape of a calendering nip

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lifting rolls, top roll means the top roll of a stack of rolls, bottom roll means

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the lower roll of the roll stack and the intermediate rolls mean the 00 o 30 rolls between the top roll and the lower roll. The top nip refers to the top calender nip formed between the top roll c i and the calender roll below the top roll, the bottom nip means the bottom 2 calender nip of the roll stack formed between the bottom roll and the bottom roll calender roll, and the spacer nip

Typically, compression is achieved in a multi-roll calender by securing the top or bottom roll of the roll stack and squeezing the stack of rolls against the fixed roll. Alternatively, both the upper and lower rollers are pressed against each other either so that neither of the intermediate rolls is locked in place or at least one of the intermediate rolls is locked in place. The deflections of the rolls can generally be compensated by deflection compensating devices on the upper and lower rolls so that the roll nipples have a uniform shape.

EP 1199404 discloses a method and apparatus for calendering a web of material. The calender has a roll stack comprising an upper roll, a lower roll and a plurality of intermediate rolls 15 and. Preferably, the roll stack forms an angle with the vertical plane. The calender has intermediate wetting devices in the direction of web travel, either immediately after the take-out roll or in conjunction with the take-out roll. In addition, the calender includes devices for providing an electrostatic charge to the web.

WO 01/55504 discloses a method and apparatus for wetting a paper or board web in a calender. The calender has a roll stack comprising a top roll, a lower roll and a plurality of intermediate rolls. Intermediate wetting is performed in the web running direction as close as possible to the next calendering nip. The intermediate humidifier is located on the web run between the output roll c3 and the calender roll. The distance between the humidifier and the calender nip following the humidifier is adjusted so that the humidifier acts

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The 1-s time is 0-1 s, preferably 100-400 ms. The wetting action time in this WO refers to the period during which the wetting action on the web occurs before the calendering action in the nip and ends when the calming nip presses cease to act.

3 U.S. Patent 6,199,477 discloses a calender having a roll stack comprising an upper roll, a lower roll and a plurality of intermediate rolls. The intermediate rollers are supported on the calender body by brackets which each form an independent bracket module. The bracket module can be attached to the calender body in one package. The support module comprises 5 articulated arms to which a roller is attached at its ends and a relief cylinder connected to the articulated arm. In the embodiment shown in Fig. 7, the external take-up rollers external to the calender body are supported on a separate body such that the take-up rolls are movable horizontally and vertically. The external take-off rollers relative to the calender body can be moved horizontally between the operating position and the worn) room position. In the operating position, the output rollers are adjacent to the roll stack and in the service position, the output rollers are spaced from the roll stack to facilitate the roll stack roller replacement. There is no humidification in the calender.

Prior art solutions do not disclose an arrangement for obtaining a sufficiently long action time on the wetting medium applied by the intermediate humidifier prior to the next calendering nip. For example, when an action time of 300 ms for a wetting medium is desired, the intermediate wetting device should be located 6 m before the next calendering nip at a running speed of 1200 m / min. When the speed is increased to 2000 m / min, the intermediate humidifier should be located 10 m before the next calender-20 pin. In the situation where the intermediate humidifier is located in the direction of web travel with the web run between the take-up roller and the calender roll, the web passage to the calender nip after the humidifier is of the order of about 1 meter. of 300 ms.

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1- Too short on the wetting medium, the web does not have enough time to wet £ sufficiently deep before the next nip. As a consequence of this, the calendering power decreases in the next calendering nip. Steaming is often used in intermediate wetting, but its efficiency is poor because the steam does not condense sufficiently into the web.

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SUMMARY OF THE INVENTION

It is an object of the present invention to provide an arrangement for obtaining a sufficiently long action time for intermediate wetting in the multi-roll calender prior to the next 5 calendering nips.

The calender according to the invention is characterized in that it comprises two guiding means external to the roller, through which the web is guided to form a wetting loop, at least one intermediate wetting device for wetting at least one of the 10 surfaces of the web in said wetting loop wherein said wetting loop is formed in a triangular manner by guiding the web from an upper nip formed by one intermediate roll of the roller to a first, upper guide member and thereafter to a second lower guide member, from which the web returns to a lower nip formed by said intermediate roll.

The method according to the invention is characterized by what is stated in the characterizing part of claim 5.

20 SC (Super Calendered) paper grades are commonly used in magazines. In SC paper, mechanical pulp is dominant and uses up to 35% minerals and fillers. The quality of the paper greatly depends on the quality of the fiber raw material and the fillers and their distribution in the web. For this reason, the production of SC paper cm is challenging. Normally, super i is used for calendering SC paper

Tt 2 o 25 calender. SC paper has a basis weight of 39-80 g / m, a gloss of 68-70 ”% (ISO) and an opacity of 90-91%. SC-A and SC-A + are new SC basic | improved paper grades that are increasing in use.

cd They partially replace the LWC (Leight Weight Coated) grades.

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By applying the intermediate wetting solution of the invention to a standard supercalender known per se, the SC-A and SC-A + paper grades can also be produced with the supercalender.

The solution according to the invention also makes it possible to easily arrange the intermediate humidifier in an adjustable position. By adjusting the position of the intermediate humidifier so that the distance traveled by the web to the calendering nip following the humidifier becomes longer or shorter, the effect of the intermediate humidifier can be adjusted.

10 BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows a multi-roll calender in which the solution of the invention can be used.

15 DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1 shows a multi-roll calender K in which the solution of the invention can be applied. Calender K comprises a roller set having eight calender rolls 11, 12, 21-26. The track consists of an upper upper roll 11 and 20, a lower lower roll 12, and six intermediate rolls 21-26 therebetween, and the output members 31, 36 associated with the intermediate rolls 21-26. and a roll coated with a flexible coating 22, 24, 25, such as a polymer roll. The upper roller 11 and lower roller 12 are preferably flexible-coated, deflection compensated (TK) rolls, preferably with movable diapers. four

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The <- member 24 and the fifth 25 spacer rolls, from the top, are of a soft surface forming a spacer n between them called a shift nip.

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co co The upper roll 11 is rigidly supported from its bearing housing 11a by the intermediate member 30 of the intermediate member 110 to the calender body R and the lower roll 12 is supported movably from its bearing housing 12a through a conductive mechanism 70 to the body R. a loading cylinder for moving the lower roll 12 in the nip plane YY to close and open the nipples.

5 The intermediate rollers 21-26 are supported from their bearing housings 22a, 24a to the first end of the link arm 42, 44. The articulated arm 42, 44 is pivotably supported by a pivot point 42a, 44a in the center of the articulated arm 42, 44 to the body R. The other end of the articulated arm 42, 44 is supported by a lightening member 52, 54, e.g. a lightening cylinder. and fourthly, the articulation arms 42, 44 of the upper intermediate roller 24 and the associated lightening elements 52, 54 for maintaining a clearer image.

Each intermediate roll 21-26 is also associated with an ejection member, i. E. An ejection roll 31, 36 for controlling the meandering path of the web W in the calender. Only the output roll 31 associated with the upper intermediate roll 11 and the output roll 36 associated with the lower intermediate roll 26 are shown in the figure for clarity of the picture. The output rollers 31, 36 are supported on the intermediate rollers 21-26 such that the output rollers 31, 36 move with the intermediate rollers 21-26.

The web W is introduced into the calender from above the top roll 11 and is guided behind the top roll 11 to the first calender nip 81a and thereafter through the second guide roll 81b to the top calender nip between the top roll 11 and the upper intermediate roll 21. After this c 1, the web W kneels from the previous calendering nip to the output roller cm and from the output roller to the next calendering nip. From the lowest calender nip between the lower roll 12 and the lowest intermediate roll i 25 26, the web W is guided to the third

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<- roll 82a and thereafter the underside 12 of the lower roll 12 guided by the fourth guide roll 82b out of the calender.

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g From the top, the web W of the nip between the fifth 24th and the sixth 25 rolls

o 30 is led out of the calender to a wetting loop KL formed by the guiding members 120, 130, from which the web W returns, from above, to the nip between the sixth 25 and the seventh 26 7 rolls. The control members 120, 130 of the wetting loop KL, which are preferably guide rolls, are supported on the supporting member 140. The supporting member 140 is further supported by an intermediate wetting device 150 for wetting at least one surface W of the web. In this case, the surface of the web W which comes into contact with the thermal roller 26 in the next 5 nips of the intermediate wetting device 150 is wetted. Here, the wetting loop KL forms a triangle with a first tip having a second lower roller 25, a second tip having a first guide roll 120 and a third tip having a second guide roll 130. The distance between the intermediate wetting device 150 and the nip thereafter. 200 ms, preferably at least 300 ms.

Here, the guide rollers 120, 130 of the wetting loop KL may be firmly supported on the supporting member 140, since the web W is constantly kept at a constant tension in the wetting loop KL. The movement of the intermediate rolls 21-26 in closing and opening the nipples extends and respectively reduces the length of the upper side and the lower side of the triangle formed by the wetting loop KL, whereby the total length of the sides of the triangle remains almost constant with respect to web tension. The guide rollers 120 and 130 may then be firmly supported on the support member 140. If space or other requirements make it necessary, the shape and position of the wetting loop KL relative to the calender roller A 20 may be changed. One or more guide rollers 120, 130 of the humidifying loop KL may be made movable in support, thereby avoiding excessive tension variations of the web, e.g., during the closing movement of the off-line calender roller.

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cm One side of the wetting loop KL is here parallel to the support member 140, whereby the effect of the intermediate wetting can be easily adjusted by adjusting the

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> the height position of the humidifier 150 on the support member 140. When the intermediate humidifier 150 g is dropped down, the effect of the intermediate humidifier is shortened.

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Alternatively, the web W could also be introduced directly into the first calendering nip between the upper intermediate roll 21 and the output roll 31 of the upper intermediate roll 21 relative to roll stack A and the output roll 36 of the lower intermediate roll 26 respectively outside the frame R. The wetting loop KL could then be formed e.g. in connection with the third lowest intermediate roll 24.

In the embodiment shown in the figure, the wetting loop KL is formed with the second lowest intermediate roll 25, but the wetting loop KL can of course be formed with any intermediate roll 21-26.

In the embodiment shown in the figure, either the upper roller 11 or the lower roller 12 is supported by a moving member 10 against the calender body by means of a loading member. Naturally, the invention can also be applied in a situation where both the upper roll 11 and the lower roll 12 are movably supported by the loading means on the calender.

In the embodiment shown in the figure, the intermediate rollers 21-26 are supported on the body by a lever arm 15 and a pivot point, whereby the own weight of the intermediate rollers 21-26 can be reduced by a relief cylinder attached to the lever arm. The movement of the intermediate rollers 21-26 then takes place around the pivot point. Naturally, the invention can also be applied in a situation where the intermediate rolls 21-26 are supported on the frame, e.g. by a guide, whereby the movement of the intermediate rolls 21-26 is mainly limited to the movement in the nip plane Y-Y. In this case, the own weight of the intermediate rolls 21-26 20 is not reduced.

In the embodiment shown in the figure, the calender has eight rolls 11, 12, 21-26, but the invention can of course be applied to any calender having a cu top roll, a lower roll, and any number of intermediate rolls.

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1- In the embodiment shown in the figure, the calender roller A is in the vertical plane, but of course the invention can also be applied to the situation where the roller A forms an angle with the vertical plane.

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In the embodiment shown in the figure, the centers of the axes of the calender intermediate rolls 21-26 are centered on a line connecting the centers of the upper roll 11 and lower roll 12, i.e. 9 nip planes YY, but the invention can of course also apply from said line. Such interleaving of the intermediate roll 21-26 may be a permanent or temporary lateral displacement of the intermediate roll 21-26 during travel. The overlapping is intended to reduce the vibration of the nipples 5.

Naturally, the solution according to the invention is also suitable for use in a situation where the calender performs various nip runs known per se. This will lock one or more intermediate rolls and use only one or some calender nips for calendering calendars. The wetting loop KL may then, contrary to what is shown in the figure, be formed in such a way that the exit of the web W from the track A and the return to the track A does not occur through the same intermediate roll 25.

In the embodiment shown in the figure, the humidifying loop KL intermediate humidifier 150 kos-15 examines the surface of the web W that comes into contact with the thermal roller 26 at the next calendering nip 150 following the intermediate humidifier device 150. The greatest benefit is obtained by the intermediate wetting, but the intermediate wetting device 150 could also be located only on the opposite side of the web W, or the intermediate wetting device 150 could be used on both sides of the web.

In the embodiment shown in the figure, the control elements 120,130 of the wetting loop KL are preferably guide rolls, but other types of control means such as sliding surfaces or air guides based on non-contact control can be used to control the web W c i in the wetting loop KL.

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cp 25 In the embodiment shown in the figure, two control means 120, 130 are used which are

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1- Preferred Embodiment. The wetting loop may also be formed by three or more control members.

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LO In the embodiment shown in the figure, the guide rollers 120, 130 of the wetting loop KL are supported by a support member 140 external to the roller A. This support member 140 is also not connected to the calender body R in this embodiment.

In the embodiment shown in the figure, the ejection members 31,36 are preferably ejection rolls, but also other control means such as sliding surfaces or air guides based on non-contact control can be used to guide the web through the web runs between the calendering nipples.

The invention has been described above by way of example with reference to Figures 10 of the accompanying drawings. However, the invention is not limited to the figures only, but different embodiments of the invention may vary within the scope of the inventive idea defined in the appended claims.

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Claims (8)

The multi-roll calender (K) comprises a body (R) and a single continuous roller (A) supported on it, the roller (A) comprising a top roll (11) and a lower roll (12), at least 5 of which are movably supported on the calender body (R), and spacer rollers (21-26) movably supported on the calender body (R) and withdrawal means (31, 36) associated with the spacer rollers (21-26), characterized in that the calender further comprises: - two relative to the roller (A) an external control member (120, 130) through which the web (W) is guided to form a wetting loop (KL), 10. at least one intermediate wetting device (150) for wetting at least one surface of the web (W) in said wetting loop (KL), an external support member (140) on which the guiding members (120, 130) and the intermediate humidifier (150) are supported, wherein said humidifying loop (KL) is formed in a triangular shape by guiding a web (W) of a single intermediate roll (25) of the upper nip first agarose, above the control element (120) and then to the other, below the control element (130), from which the web (W) to return said intermediate roll (25) to form a lower nip. Calender according to Claim 1, characterized in that the distance between the at least one intermediate wetting device (150) and the calendering nip following the at least one intermediate wetting device (150) in the direction of travel of the web is formed so long that the wetting medium has a duration of at least 200 cm. ms, preferably at least 300 ms. S 25 CO 1- Calender according to Claim 1 or 2, characterized in that said at least two guiding members (120, 130) are supported stationarily on a support member (140) external to the track (A). LO 00 o o 30 Calender according to one of Claims 1 to 3, characterized in that said at least two guide members (120, 130) are guide rollers. A method in a multi-roll calender (K) comprising a frame (R) and a single continuous roller (A) supported on it, the roller (A) comprising a top roll (11) and a lower roll (12), at least one of which is movably supported on the calender frame (R) ), as well as spacers (21-26) movably supported on the calender body (R) and output means (31, 36) associated with the intermediate rolls, characterized in that: - a wetting loop (KL) is formed with respect to the two rollers (A). external wetting means (120, 130), - wetting at least one surface of the web (W) with an intermediate wetting device (150) in said wetting loop (KL), - supporting the control means (120, 130) and an intermediate wetting device (150) with the external supporting member (140), - forming a wetting loop (KL) into a triangular shape by guiding the web (W) from the upper nip formed by one intermediate roll (25) of the rack (A) to the first guide member (120) above and further to the second guide member. to the s-member (130) from which the web (W) is guided to the lower nip formed by said intermediate roll (25). Method according to Claim 5, characterized in that a distance between the at least one intermediate humidifier (150) and the calendering nip following the at least one intermediate humidifier (150) in the direction of travel of the web is formed such that the duration of the humidifying medium is at least 200 cpm. , preferably at least 300 ms. δ CM o 25 A method according to claim 5 or 6, characterized in that said at least two control means (120, 130) are stationary supported by a support means (140) external to the track (A). CD co δ Method according to one of Claims 5 to 7, characterized in that each of said at least two guiding members (120, 130) is formed from a guiding roll.