A continuous paper web of several meters in width which is passed directly from a paper machine or from a finishing treatment apparatus connected thereto in a continuous, on-line type manner, or from a separate off-line type finishing treatment apparatus is reeled in the reel- up to form successive machine reels. These large machine reels, which substantially comply with the production width of paper web function as kind of intermediate storages between off-line type finishing processes. Such further processing may relate for example to the coating and calendering of paper. At a later off-line treatment stage in the treatment of a full-width paper web the web reeled on such machine reels substantially in the production width is unwound and cut in the longitudinal direction into narrower part webs of which customer rolls are formed at a later stage. The width and size of the customer rolls are adjusted to comply with the requirements of the customer and the further use of the rolls.

When the aim is to constantly increase the web width, running speed and degree of utilization of paper machines, the result is a tendency to produce machine reels which have even larger width and diameter and thereby also a greater overall weight. At present, the width of the reels typically already exceeds 50 tonnes in wide machines.

In the following, the practical problems and drawbacks caused by the increase in the overall weight of machine reels and the increase in the width of the paper web in the reeling up process will be described.

Especially in the reeling process of dense and heavier paper grades, for example in the reeling of printing papers, the amount of paper ac- cumulated on a reeling core i. e. a so-called reel spool, causes deflec-

tion in the reel spool which is only supported at its ends and whose length equals the web width. This deflection constitutes a significant factor which restricts and complicates the reeling up process, as will be described hereinbelow.

The state of art currently in use in the reeling up is described for exam- ple in the book by Mikko Jokio: Papermaking Part 3 Finishing, pub- lished by Fapet Oy, ISBN 952-5216-10-1,1999, pp. 143-235.

In reel-ups a paper web is brought to the actual reel spool via a reeling drum, a so-called nipping cylinder, the paper web being reeled on said reel spool. The pressing force, i. e. so-called nip force between the nip- ping cylinder and the roll to be formed on the reel spool is one of the essential variables to be adjusted in the reeling up process, by means of which the tightness of the roll to be formed on the reel spool is con- trolled. The used nip force is not necessarily constant, but it can be al- tered in connection with the same paper grade as a function of the amount of paper accumulated on the reel spool, and for paper grades that differ from each other it is possible to use different values of the nip force that change in different ways as a function of the amount of paper accumulated on the roll. Typically, the aim is to reduce the tight- ness, i. e. the density of the material reeled on the reel spool in the di- rection of the radius of the roll, wherein too tight surface layers do not compress the lower layers.

The increasing deflection of the reel spool caused by the mass of the paper accumulated on the reel spool results in that the nip force be- tween the nipping cylinder and the paper roll accumulated on the reel spool does not remain constant in the transverse direction of the paper web, i. e. in the longitudinal direction of the reel spool. At the ends of the reel spool, closer to the supporting points, the deflection of the roll downwards under the effect of gravitation is smaller than in the middle of the roll, which, in turn, causes a change in the nip force in the longi- tudinal direction of the roll. In addition to the mass of paper accumu- lated on the roll, the exact nature of the change at a given time also depends on the location of the nipping cylinder with respect to the reel spool either directly on the side of the reel spool, or in a corresponding

manner above or below the same (see for example Papermaking Part 3, pp. 151-152).

As a result of the above-described phenomenon, the manufacture of a large mass machine reel which substantially corresponds to present web widths and is supported only at its ends, and in which the profile of density in the radial direction of the roll would remain constant in the longitudinal direction of the reel spool is not, in practice, possible by means of methods of prior art.

It is easy to understand that a change in the radial density profile of the machine reel in the longitudinal direction of the reel spool as a result of the above-described variation in the nip force causes stress forces inside the roll, which easily lead to degradation of the properties, or immediate damage of the paper web reeled on the roll.

When the reel spool rotates during reeling, the deflection of the reel spool also causes a cyclically varying force inside the paper roll, be- cause it can be considered that every time the reel spool rotates half a revolution, it gradually deflects from its extreme position at that time to another, opposite extreme position, causing a corresponding deforma- tion in the paper roll which is already formed on the reel spool.

The above-described phenomena caused by the deflection of the reel spool can damage the paper web reeled on the reel spool in the sur- face layers of the roll or deeper in the roll. In addition to the changes or damages caused in the paper web directly in connection with the reel- ing-up process, the stresses that remain in the roll complicate the fur- ther processing of the web in connection with the next unwinding proc- ess and off-line treatments.

The motion of the paper web itself as well as the rapidly rotating rolls cause strong airflows on the surface of the paper web and on the sur- face of the rolls, which can result in that air is passed underneath the outermost layer/layers of the paper web reeled on the machine reel, and further in the generation of an air bag in front of the nipping cylinder that tightens the roll. If the air bag collapses through the nip,

this causes wrinkle flaws, i. e. so-called crepe wrinkles in the paper web that is being reeled on the reel spool. The air bag can also be formed before the nip underneath the paper web travelling on the nipping cyl- inder, if the used nip force is so high that the flow of air through the nip to the reel itself is prevented. The formation of the air bag that compli- cates the reeling up process occurs especially with denser and less porous paper grades when a full-width paper web is reeled up. Typical examples of this include for example reeling up of coated or calen- dered paper grades into wide machine reels.

To prevent the formation of air bags it is possible to use a nipping cyl- inder equipped with a grooved or perforated surface. Examples of such nipping cylinders are presented in Papermaking Part 3, pp. 157-158. It is, however, a common problem in such solutions of prior art that the grooved or perforated surface of the nipping cylinder also easily works the paper web itself in an undesirable manner.

It is an aim of the present invention to introduce a method in which it is possible to avoid the problems related to the reeling of wide machine reels of even greater mass due to the above-described deflection of the reel spool and/or formation of air bags. To attain this purpose, the method according to the invention is primarily characterized in what will be presented in the characterizing part of claim 1. The reel-up accord- ing to the invention, in turn, is characterized in what will be presented in the characterizing part of claim 10.

The method and device according to the invention are characterized by the following features which improve the performance and controllabil- ity of the reeling up process and maintain the quality of the paper webs contained in the paper reels attained as a result of the process.

When a paper web passed from the paper machine and/or finishing treatment is slit into part webs as early as possible, preferably already before the first reeling up stage, the loading and stresses inside a sin- gle roll caused by the deflection of the one-piece reel spool remain considerably smaller when compared to the case of a full-width paper web/roll. In a narrower roll the stresses can also be more easily re-

lieved through the differential motion of the paper layers without tearing the paper web when compared to the case of a wide web.

The reeling of two or more adjacent part webs on the spool gives the possibility to adapt the reeling of said part webs in such a manner that a space remains between the corresponding rolls for a supporting member/members by means of which the reel spool can, in addition to end support, also be supported at one or several supporting points in the longitudinal direction of the axis. By means of this additional support it is possible to prevent/reduce the deflection of the reel spool.

When a full-width paper web is divided into part webs by slitting, the susceptibility of the production process to errors in the width direction of the web is at the same time reduced, i. e. the so-called profile toler- ance of the process is increased because the effect of the web section of poor quality is restricted to the area of only one or few part webs.

The air trapped between the rolls built up on the reel spool and paper webs, and/or between the nipping cylinder and paper webs is capable of being discharged via the edges of narrow part webs considerably more easily than in the case of the full-width web. This reduces the formation tendency of an air bag in the reeling up process, especially in webs that permeate air poorly.

If necessary, it is possible to provide separate nipping cylinders for in- dividual part webs in order to enable more accurately the compression of each part web and the corresponding roll each with an equally high nip force in the reeling up. In the case of deflection of the reel spool this cannot be achieved in a situation in which one one-piece full-width nipping cylinder is used. When necessary, different part webs can also be compressed by means of nip forces that differ from each other.

When a one-piece nipping cylinder is used, the cylinder in question can be of a so-called deflection compensated type, wherein the nip force of the rolls corresponding to different part webs can be compensated according to the deflection of the reel spool.

When the above-mentioned narrower nipping cylinders are used, it can be assumed that the flow of air to the rolls is further reduced also because the contact line, so-called nip line between each nipping cyl- inder and corresponding roll, remains straighter and tighter. The differ- ence is in its clearest when the situation is compared with the case of a full-width non-deflection compensated nipping cylinder. From between the part webs and corresponding rolls air can also be discharged more easily.

In the following, the invention will be described in more detail by means of examples and with reference to the appended drawing, in which Fig. 1 shows the method according to the invention schematically in a top-view, Fig. 2 illustrates in a certain situation in a side-view the additional supporting of the reel spool between the part webs in addi- tion to the normal end support, Fig. 3 shows in a top-view the use of a one-piece, deflection com- pensated nipping cylinder when compensating the change in the nip force in the rolls corresponding to different part webs caused by the deflection of the reel spool, Fig. 4 shows the use of separate nipping cylinders in a top view.

Fig. 1 shows a top-view of an apparatus for reeling up, in which a full- width paper web W (whose width corresponds to the width of production or the treatment width of the finishing stage) is passed in the direction shown by an arrow to the operating range of cutting members in a cutting station C. The cutting members can be mechanical blades according to prior art, for example rotating blades or the like which make longitudinal slits in the paper web passing by, said slits dividing the web into narrower part webs W1 to W5. The division into part webs can also take place without actual mechanical blades, wherein the cutting can be conducted for example as a so-called water jet cutting. According to a commonly used solution, the cutting

members (blades) are placed in pairs above and below the paper web, and these so-called upper and lower blades can be moved synchronically with respect to each other in the lateral direction of the paper web according to the desired part web width by means of mechanical solutions of prior art. In Fig. 1, the purpose of the arrows at the location of the respective cutting members of the different part webs is to illustrate the possibility to adjust the cutting members in the lateral direction.

After slitting, the part webs W1 to W5 proceed to the spreading and guiding apparatus S, which contains means for guiding the part webs apart from each other in the lateral direction if necessary, and via a nipping cylinder D further around the reel spool R into separate rolls R1 to R5. The spreading and guiding apparatus S can be implemented by means of mechanical solutions known as such, and in a similar man- ner, it is possible to use any known mutual modes of operation of the nipping cylinder and the reel spool as well as necessary carrier roll and auxiliary roll solutions in the reeling up of the webs by means of the nipping cylinder D to the reel spool R. In addition to a mere nipping cylinder, it is also possible to use a combination of a nipping cylinder and a belt, or another mechanical solution known as such that func- tions in a corresponding nip-like manner. The reel spool R may be of a known type, i. e. a metal body roll arranged rotatable in bearing hous- ings at its ends. When the reel-up in question is a centre-drive assisted reel-up, the reel spool is rotated with a drive of its own.

When the rolls R1 to R5 reach their desired maximum peripheral size, the act of bringing a new reel spool and threading the webs around said spool, as well as the removal of the finished roll can be implemented by methods known as such, by means of which the change of the reel spool can be carried out without changing the speed of the paper web W arriving in the apparatus of Fig. 1.

If necessary, the slitting into part webs can be temporarily interrupted either for the all or at least some part webs until the threading of the part web/webs to the new reel spool has been finished, and the reeling around the new reel spool has begun. Thus, the reel change, i. e. the

act of guiding the web around the new reel spool can be conducted in full width, if necessary.

The apparatus shown in Fig. 1 contains one set of cutting mem- bers/cutting member pairs used in the slitting. In an another embodi- ment of the invention, the number of cutting members/cutting member pairs can be selected in such a manner that it is possible to refer to two so-called sets of blades, wherein when the first set of blades is guided against the paper web and performs slitting, the second set of blades, which at that moment is off the contact with the paper web, can be pre- adjusted so that it corresponds to the new width values of the part webs. In this way, when the reel spool is changed, it is possible to guide said first set of blades off the paper web first (or e. g. in water jet cutting the cutting jet can be turned off), and when the paper web has threaded to the new roll, it is possible to move said second set of blades directly in contact with the paper web (or e. g. in water jet cutting the cutting jet can be turned on), thereby starting the slitting without a delay required by the adjustments conducted in said first set of blades in the lateral direction of the paper web.

Fig. 2 illustrates the roll deflection caused by the weight of the paper reeled on the reel spool R in a situation in which a conventional end support (EB1 and EB2) is used for supporting the roll. The deflection of the reel spool in relation to the straight axial line (marked with a dotted line), which deflection also corresponds to change occurring in the nip line, is illustrated by means of a dotted line in Fig. 2.

Fig. 2 also illustrates a support of the reel spool according to the pre- sent invention between the part rolls formed on the reel spool in such an embodiment in which two intermediate supports (IB1 and IB2) are used to prevent/reduce the deflection/vibration of the reel spool. The invention is not, however, restricted to the use of two intermediate sup- porting points according to Fig. 2, but there may be one or more inter- mediate supporting points, and the location of the same in the lateral direction of the reel spool can be selected in such a manner that it is appropriate in view of the number and width of part webs/rolls manu- factured at a given time.

When the intermediate support of the reel spool is used, a preferred embodiment for implementing the bearing arrangement in the loading point between the supporting member and the rotating reel spool is the use of such a bearing application which contains a wide contact sur- face and/or uses gas or liquid as an intermediate agent, in which the surface pressure and friction produced on the surface of the reel spool are such that the normal surface of the reel spool can directly function as the second bearing surface without any alterations. Thus, the loca- tion of the intermediate supporting point/points can be freely selected so that they are appropriate in view of the number and width of the part webs/reels without any alterations being necessary in the reel spool itself.

The invention is not, however, restricted solely to the use of a bearing application according to the description above, but the intermediate support of the reel spool in the loading point between the supporting member and the rotating reel spool can also be implemented by means of mechanical bearing solutions known as such in which the surface of the reel spool that functions as the second bearing application surface is treated and/or altered in the required manner.

Fig. 3 shows the principle of using a one-piece deflection compensated nipping cylinder D for controlling the reeling up of the part rolls R1 to R5. The adjustment of the longitudinal profile of curvature of the nipping cylinder can be implemented by utilizing hydrostatic, hydraulic or other types of force members and cylinder structures of prior art.

Fig. 4 illustrates the act of controlling the reeling up of part webs by using a separate, individually adjustable nipping cylinder (D1 to D5) for each part roll R1 to R5. It should be noted that the invention is not, ac- cording to the details shown in Fig. 4 restricted to such an embodiment, in which each part web and corresponding part roll has a nipping cylin- der of its own, but the number of nipping cylinders can also be selected in such a manner that one nipping cylinder is used for controlling the reeling of two or more adjacent part webs.

In the examples shown in Figs. 1 to 4, the slitting into part webs and the reeling up of these part webs on a reel spool is implemented in such a manner that the part webs/rolls are equally wide when com- pared to each other, and the spaces between the corresponding rolls in the reel spool are equal in size. The invention is not, however, re- stricted solely to this embodiment, but the number and width of the part webs/rolls as well as the spaces between the part rolls in the reel spool can vary from those shown in Figs. 1 to 4, if necessary. Furthermore, the invention is not restricted to the embodiment, in which all part webs/rolls would be equally wide, but the full-width paper web can also be slit in such a manner that part webs of two or more different widths are formed, and these part webs can be further reeled up on the reel spool in such a manner that the spaces between the part rolls that are being formed differ in size.

It is also possible that in connection with the slitting (C in Fig. 1) and the spreading and guidance (S in Fig. 1) of the part webs thereafter, a part/parts of the paper web, advantageously a part/parts of poor quality is/are guided aside, and said part/parts of the paper web is/are not reeled on the reel spool R. The part webs can, of course, be separated from each other by removing a part of suitable width from the paper web between the part webs reeled into part reels without having to change the travel direction of the part webs separately with the spreading and guiding means (S).

The invention is not restricted to be used in a reeling up process that takes place at a given stage of the papermaking process, although it is advantageous to conduct slitting and the thereafter following reeling up of the part webs into adjacent rolls on the reel spool already as a first reeling up process conducted in the end of the on-line type continuous process. If, however, the paper web to be treated obtains such proper- ties at a later off-line treatment stage which complicate the reeling up of the full-width web and/or worsen the drawbacks caused by the deflec- tion of the reel spool, it is possible to use the method and device ac- cording to the invention as late as in the reeling up process following said finishing treatment. The finishing stage of the aforementioned kind can be for example coating of paper web, whereby the air permeability of the web is reduced. The finishing stage can also be off-line calendering, such as supercalendering.