WO2010052374A1

WO2010052374A1 - A method in connection with a slitter winder for a fiber web

Info

Publication number: WO2010052374A1
Application number: PCT/FI2009/050901
Authority: WO
Inventors: Petri Enwald; Heikki FÖHR; Kenneth ÅKERLUND
Original assignee: Metso Paper Oy
Current assignee: Valmet Technologies Oy
Priority date: 2008-11-10
Filing date: 2009-11-09
Publication date: 2010-05-14
Anticipated expiration: 2011-05-10
Also published as: FI121956B; FI20086060L; AT511278A1; FI20086060A0; AT511278B1; DE112009002639T5

Abstract

The present invention relates to a method in connection with a slitter winder (1) for a fiber web according to which method a web (W) slit in the slitting section of a slitter winder is wound into partial web rolls having a certain diameter and according to which method the machine roll (15) to be unwound in the primary unwinding station (35.1) is unwound by a drive (36.1) connected to the machine roll down to a certain diameter, and the machine roll is transferred from the primary unwinding station. The web tension between the machine roll and the winding section is controlled mainly by means of a tension control arrangement (5, 7, 9) independent from the rotational position of the machine roll.

Description

A method in connection with a slitter winder for a fiber web

[001] The present invention relates to a method according to the preamble of patent claim 1 according to which method a web slit in the slitting section of a slitter winder into partial webs is wound into partial rolls having a certain diameter and the machine roll to be unwound in the primary unwinding station is unwound by a drive connected to the machine roll down to a certain diameter after which the machine roll is transferred from the primary unwinding station.

[002] As the state of the art discloses, a machine roll is unwound at a slitter winder and the wide web is slit in the slitting section of the slitter winder into several narrower partial webs which are wound at the winding section around winding cores such as bobbins to form customer rolls. When the customer rolls prepared at the same time from each partial web are finished the slitter winder is stopped and the rolls, or the so-called set, are removed from the machine. After this the process is continued in winding a new set. These stages are repeated in cycles until paper runs out from the machine roil, whereby the machine roll is replaced and the operation start over as unwinding of the new machine roll. The partial web winder can be a carrier roll type winder where the partial web rolls are wound supported by carrier rolls and through a winding nip between the web roll being formed and a second carrier roll. The partial roll winder can also be a center winder where the partial web roll is supported at the center and the winding takes place through the nip between the web roll being formed and the winding cylinder.

[003] When unwinding web from the unwinder a machine roll change is carried out when the machine roll is becoming empty; in many unwinders of slitter winders this is still performed entirely manually. A so-called automatic machine roll change is also known, whereby according to the state of the art methods the slitter winder is stopped and the old web is caught with a retaining means, for example a suction means, and cut and subsequently the empty machine roll has been removed and replaced by the next machine roll to be unwound. The end of the new machine roll web has been taken to the joining station and the ends of the old web and the new web are spliced together applying various bonding methods while the slitter winder and the unwinding apparatus have been stopped. An arrangement of this kind known in the prior art is disclosed in EP patent publication no. 1 163 178. However, the approach described here is some- what slow as far as its operation is concerned. In an unwinding solution of another type the change of roll is carried out so that the old nearly empty roll is lifted off from the unwinding station so that a new roll can be brought to the unwinding station. A drawback with also the solutions of this type known in the prior art is the decrease of capacity caused by the time con- sumed by the machine roll change.

[004] There are also solutions known from th prior art for effecting continuously operating unwinding. US publication no. 6386477 B1 discloses an unwinding system which comprises two unwinding stations provided with stationary drives of their own, and a movable auxiliary drive. The auxiliary drive allows maintaining web tension while the roll being unwound is transferred from the primary unwinding station to the secondary unwinding station. According to the publication the unwinding of a full roll is carried out at the primary unwinding station down to a certain roll diameter after which the roll is transferred to the secondary unwinding station for unwinding and a new full roll is brought to the primary unwinding station. A drawback in this kind of an arrangement is that the additional drive provided at the service side interferes with the arrangement of the platforms needed for the service and operation personnel. Further the change of drive during the unwinding presupposes a very complicated control system and precisely operating apparatus to ensure that the tension of the wire to be unwound does not vary excessively during the drive change.

[005] An object of the present invention is to provide a slitter winder and a method of using the slitter winder where the decrease of capacity caused by machine roll change is minimized and where operation dependability has been maximized.

[006] The objects of the invention are achieved mainly by a method in connection with a slitter winder according to which method the web slit into partial webs at the slitting section of a slitter winder is wound into partial web rolls having a certain diameter and the machine roll being unwound is unwound in the primary unwinding station by means of a drive coupled with the machine roll down to a certain diameter and subsequently the machine roll is transferred from the primary unwinding station. It is characteristic of the invention that the tension of the web between the machine roll and the winding section is controlled during said transfer mainly by a tension control arrangement independent from the rotational position of the machine roll.

[007] This provides among other things the advantage that synchronous moving of the drive or other corresponding arrangement synchronously with the machine roll during the transfer is avoided and in this way the number of so-called drive changes during the unwinding process is reduced.

[008] Before the machine roll is transferred away from the primary unwinding station the machine roll is preferably released from the primary unwinding station and is transferred away from the primary unwinding station so that rotation of the machine roll is substantially prevented by form locking. [009] In practice the rotation is prevented by form locking by providing for example in connection with the support of the machine roll retaining members based on form locking which can be used to prevent the machine roll from rotating.

[0010] According to an embodiment the control of the web tension and/or length during the transfer of a machine roll by means of a tension control system independent from the rotational position of the machine roll is at least partly effected by means of the winding-up of the slitter winder. In practice the drives of the winding section during the transfer of the machine roll are controlled so that the change in the length and/or tension of the web is compensated by operating the wind-up section. Then the apparatus needed is simple and it is possible to effect the control of the web length and/or tension very accurately.

[0011] According to another embodiment the tension of the machine roll during the transfer is controlled at least partly by one or several web- accumulator/s.

[0012] According to yet another embodiment the tension of the machine roll during the transfer is controlled at least partly by one or several tension confining mean/s.

[0013] The machine roll transfer is preferably performed at least partly during a set change whereby the tension of the web is more easily controlled. The machine roll is transferred from the primary unwinding station to the secondary unwinding station preferably during the set change preceding the machine roll change.

[0014] The machine roll is preferably transferred from the primary unwinding station essentially in a horizontal movement to the secondary unwinding station where the final stage of the unwinding of the machine roll is performed. At the same time as the final stages of the unwinding of the machine roll are carried out a new machine roll is brought to the primary unwinding station and the end of the web of the new machine roll is taken to the vicinity of the splicing station while unwinding is proceeding. When the unwinding of the web in the secondary unwinding station has been finished, the splicing of the web to the web of the new machine roll brought during the unwinding to the vicinity of the splicing apparatus is performed. The end of the web of the new machine roll can be taken to the vicinity of the splicing apparatus essentially in full width of the web. In some applications the web end can be threaded wedge- shaped whereby there are means provided in connection with the unwinding apparatus for forming the wedge in the web end, i.e. preferably an automatic wedge cutting apparatus.

[0015] According to a preferred embodiment of the invention, when controlling the tension and/or the length of the web running to the slitting section by means of a tension control arrangement independent from the rotational position of the roll, one or several of the following tension control arrangements independent from the rotational position of the roll are used: control of the winding apparatus drives/ change in the rotational position of the customer rolls; web accumulator; tension confining means.

[0016] Numerous advantages are achieved with the invention. The me- thod remarkably improves the overall efficiency of the slitter winder as a minimum time is required for splicing the webs during a machine roll change.

[0017] According to an embodiment of the inventions the splicing is car- ried out so that, simultaneously as the webs coming from the secondary unwinding station and the primary unwinding station are joined together the unwinding is carried out at a velocity different from zero velocity. Then the splice becomes slanted in the web running direction which is a joint acceptable for further processing, i.e. a so-called commercial splice.

[0018] The invention and its operations are described below with refer- ence to the appended schematic drawing figures of which

Fig. 1 illustrates schematically a web slitter winder according to an embodiment of the invention, Fig. 2 illustrates schematically a web slitter winder according to another preferred embodiment of the invention,

Fig. 3 illustrates schematically a web slitter winder according to yet another preferred embodiment of the invention, and

Fig. 4 illustrates schematically a web slitter winder according to yet another preferred embodiment of the invention.

[0019] Figure 1 illustrates schematically a web slitter winder 1 according to an embodiment of the invention. It comprises a winding apparatus 5 for partial webs, a slitting section 10, and an unwinding apparatus 20 for machine rolls 15 as seen from the side. The unwinding apparatus 20 comprises a body 25 provided with adjacent and parallel rails 30 to support the machine rolls 15 at both ends of the unwinding shafts via bearings in the same way (only one has been illustrated). Preferably the rails are essentially horizontal. The unwinding apparatus comprises a primary unwinding station 35.1 and a secondary unwinding station 35.2 both of which have been provided in the embodiment of the figure with a stationary drive 36.1 , 36.2. Both the drives have a motor and a coupling member via which the motor can be coupled to the unwinding shaft of the machine roll. The stationary drive here means that the drive can be coupled to the unwinding shaft only when it is in the unwinding station.

[0020] The winding apparatus 5 is in this embodiment a carrier roll/belt winder but it is obvious that the winding apparatus can be of any type suitable for winding partial webs. Further, the winding apparatus comprises at least one drive 5.1 , 5.2 by means of which the winding force can be directed to the rolls to be formed and thus the partial webs can be converted into partial web rolls.

[0021] The unwinding apparatus 20 comprises a first support and control apparatus 40.1 and a second support and control apparatus 40.2. The support and control apparatus 40.1 , 40.2 engages the movement of machine roll on rails 30 so that the movement and the position of the machine roll is determined by the control apparatus 40.1 , 40.2. The first support and control apparatus 40.1 has been furnished in connection with a first rail 45.1 supported on the body 25, the control apparatus 40.1 being arranged to be moved along said rail by means of an actuator 210. Correspondingly, the second support and control apparatus 40.2 has been furnished in connection with another rail (not illustrated) supported on the body 25, the control apparatus 40.2 being arranged to be moved in a corresponding way along said rail. The first support and control apparatus 40.1 and the second support and control apparatus 40.2. as well as the first and the second rail have been provided on different sides of the body 25, thus the first support and control apparatus 40.1 and the second support and control apparatus 40.2 are able to bypass each other. The movement range of both the support and control apparatus extends from the primary unwinding station 35.1 to the secondary unwinding station 35.2.

[0022] Web W is guided from the machine roll via the slitting section 10 to the winding section 5 guided by the guide rolls 70 of the web. The guide rolls are preferably stationary in position. A web splicing apparatus 60 has been provided in the web transfer portion between the web unwinding apparatus 20 and the slitting section 10 by means of which the webs placed side-by-side can be attached to each other and the extra portions such as web ends can be cut out. The web splicing apparatus 60 may comprise one element, or two elements whereby the first element of the splicing apparatus is located on the first side of the running path of the web W and the second element on the other side. During the normal operation of the slitter winder the elements of the web splicing apparatus are situated at a distance from each other but for the splicing operation they are brought together, leaving the webs to be joined between the elements of the splicing apparatus. The type and the operation of the splicing apparatus preferably allows connecting the webs arriving from the secondary unwinding station and the primary unwinding station to each other while the webs are moving whereby the splice becomes slanted in the web running direction.

[0023] According to an embodiment of the invention the full-width web W is unwound at a slitter-winder, slit to partial webs at the slitting section 10 and partial web rolls are wound at the winding apparatus 5. The unwinding is started at the primary unwinding station 35.1 and the machine roll 15 to be unwound is unwound at the primary unwinding station 35.1 down to a certain diameter after which the machine roll 15 is transferred to the secondary unwinding station 35.2 guided by a support and control means and an actuator 210. The rest of the unwinding of the machine roll is carried out in the secondary unwinding station 35.2.

[0024] At the same time as said machine roll end portion is being unwound, a new machine roll 15 is brought to the primary unwinding station 35.1 and the end of the new machine roll web W is brought to the vicinity of the splicing apparatus while the unwinding is in progress. Then a machine roll change causes as short a break in the production as possible, or no break at all, depending on the splicing method. [0025] A control arrangement 200 has been provided in connection the unwinding apparatus to guide the operation of the slitter winder according to an embodiment of the invention; the arrangement is described here particularly in connection with the transfer of the machine roll 15 from the primary unwinding station 35.1 to the secondary unwinding station 35.2 as far as the actuator 210 of the support and control apparatus and the drives 5.1 , 5.2 of the winding apparatus 5 are concerned. The control arrangement has a data transmission connection with the drives 5.1 and 5.2 and the actuator 210 of the support and control apparatus.

[0026] . The machine roll has both at the primary and at the secondary unwinding station a certain rotational position α. In unwinding, the rotational position changes constantly, thus the web is unwound from the machine roll at a certain speed. The speed is also influenced by the diameter of the machine roll at that time. The rotational position at the unwinding is determined by the drive coupled to the machine roll 15.

[0027] In Figure 1 the relatively large machine roll in the primary unwinding station 35.1 is depicted by a uniform line. When the size of the roll is adequately small, in other words when the slitter winder has been running sufficiently long, the machine roll 15 is transferred by means of an actuator 210 and a support and control apparatus to the secondary unwinding station 35.2. Before the transfer, the drive 36.1 of the primary unwinding station coupled to the machine roll is detached from the machine roll. According to the invention, the tension of the web W running from the machine roll 15 to the slitting section 10 is controlled mainly by a tension control arrangement independent from the rotational position of the machine roll 15. This means that the rotation of the machine roll is not actively acted on during the transfer. In the embodiment of Figure 1 the tension control arrangement independent from the rotational position of the machine roll comprises a combination of the control system of the actuator 210 and at least one drive 5.1 of the winding apparatus 5. Thus, during the transfer the machine roll 15 is transferred away from the primary unwinding station 35.1 substantially undriven and the tension of the web W of the machine roll 15 is controlled mainly by means of the winding 5 of the slitter winder. The drives of the winding section is controlled so that the while the machine roll 15 moves away from the primary unwinding station 35.1 the changing length of the web path is compensated by winding up the customer rolls 12 by means of at least one drive of the winding section 5. In this way a change in the rotational position of the customer rolls is produced by means of the drive. Thus, no separate movable drive or a brake device following the machine roll is needed for the transfer of the machine roll 15.

[0028] According to an embodiment the rotation of the machine roll 15 is preferably prevented during the transfer by form-locking. During the transfer of the machine roll the rotation of the machine roll 15 is prevented based on form-locking by means of a locking apparatus 36.3 in connection with the machine roll or its support and control apparatus.

[0029] A control arrangement 200 has been provided to control the operation of the actuator 210 and the drives 5.1 , 5.2 during the transfer as follows. At the same time as the machine roll 15, which has been depicted in Figure 1 in a transfer situation by a dashed line, is transferred towards the secondary unwinding station 35.2 the path of the web W running from the roll to the winding station 5 is changed. Then the drive 5.1, 5.2 of the winding apparatus is used so that the excessive shortening of the distance is compensated by changing the length of the web from the machine roll 15 to the winding apparatus 5. This is accomplished advantageously by winding a corresponding amount of the web to partial web rolls 12. At the same time the operation of the slitting section 10 continues. In this way the length of the web W running from the machine roll 15 to the slitting section 10 is controlled during the transfer of the machine roll 15 from the primary unwinding station 35.1 to the secondary unwinding station 35.2 at least partly by using the winding apparatus 5 of the slitter winder.

[0030] In addition to the control of web length, some embodiments allow taking the operation to a more advanced level by maintaining a certain web tension during the transfer of the machine roll. The accuracy of the web tension control may be improved by providing the arrangement with a web tension measurement 72 which is here disposed in connection with the guide roll. Now the real value of the web tension can by used in the control of the drives of the winding apparatus 5.

[0031] In the embodiment illustrated in Figure 1 the transfer of the machine roll comprises, due to machine geometry and the web unwinding direction, a phase in which the path of the web from the machine roll to the winding apparatus 5 at first decreases and them starts to increase during the progress of the transfer. This precise phase has been illustrated with the machine roll 15 depicted with a dashed line. Here the web unwinding from the machine roll meets the guide roll 70 on the left in the figure, which bends the path of the web while the transfer proceeds and thus extends the path of the web from the machine roll 15 to the winding apparatus.

[0032] . According to an embodiment of the invention, the rotation direction of the winding apparatus is changed in this situation and the length of the web is increased by unwinding web from the partial web rolls. I must be realized that the need to change the web length caused by the change in the path length typically requires winding/unwinding less than one round of the web from the finished customer rolls to compensate the change in the web path length. [0033] According to another embodiment in the transfer of the machine roll to the stage described above where the path of the web from the machine roll to the winding apparatus 5 at first becomes shorter and then start to grow, the web length is adjusted by using the winding section 5 so that, prior to this stage, the length of the web is shortened by the amount essentially corresponding to the difference between the shortening of the web before said stage and the increasing of the length following said stage.

[0034] When the machine geometry and/or the web unwinding direction is such that the distance from the machine roll 15 to the winding apparatus becomes shorter the whole time when the machine roll is being transferred to the secondary unwinding station 35.2 the compensation of the change preferably includes only shortening of the web length. In Figure 1 the position of the machine roll at secondary unwinding station 35.2 is illustrated with a dotted dashed line. Here expressly the distance between the stations depicted with a dashed line and a dotted dashed line increases during the transfer of the machine roll to the secondary unwinding station 35.2.

[0035] Figure 2 illustrates schematically a web slitter winder 1 according another embodiment of the invention. It also comprises a winding apparatus 5 for partial webs, a slitting section 10 and an unwinding apparatus 20 for machine rolls 15, as seen from the side. As for their structure and operation these correspond to the components of the slitter winder illustrated in Figure 1. The drives of the primary unwinding station 35.1 and the secondary unwinding station 35.2 have been provided with a motor and a coupling, by means of which the motor may be coupled to the rotating shaft of the machine roll. [0036] The web is guided from the machine roll via the slitting section 10 to the winding section 5 guided by web guide rolls 70. The guide rolls are preferably stationary in position. Like in the embodiment of Figure 1 , also in this embodiment a web splicing apparatus 60 has been provided in the web transfer portion between the web unwinding apparatus 20 and the slitting section 10.

[0037] The full-width web W is unwound at a slitter winder according the embodiment of Figure 2, and slit to partial webs at the slitting section 10 and partial web rolls are wound at the winding apparatus 5. The unwinding is performed the same way as with the unwinding apparatus of the embodiment of Figure 1. The slitter has been provided with a web accumulator 7. The web accumulator comprises web guide rolls by means of which the path of the web from the unwinding to the winding can be extended or decreased. In Figure 2 the accumulator comprises two rolls which have been connected to the ends of levers rotatably supported at the center. By turning the levers, which here are at both ends of the rolls, the rolls are caused to move so that the wrapping of the web on the rolls may be changed. Figure 2 illustrates with a dashed line another position of the web accumulator. By turning the levers a certain amount of web may be stored in the web accumulator or released from the web accumulator 7. The web accumulator may be implemented in various different ways and the arrangement may comprise several separate web batteries. Another alternative is for example parallel rows of rolls via which the web has been arranged to run in turns and the distance of which from one another is adjustable.

[0038] A control arrangement 200 is provided in connection with the unwinding apparatus, disposed to control the operation of the slitter winder according to an embodiment of the invention and which is here described particularly for the part of the support and control apparatus actuators 210 and the web accumulator in connection with the transfer of the machine roll 15 from the primary unwinding section 35.1 to the secondary unwinding section 35.2. The control arrangement has been arranged to have data transmission and control connection with the web accumulator 7 and also with drives 5.1 and 5.2 and with the actuator 210 of the support and control apparatus.

[0039] In Figure 2 the relatively large machine roll in the primary unwinding station 35.1 has been depicted by a uniform line. When the size of the roll is adequately small the machine roll 15 is transferred by means of the actuator 210 and the support and control apparatus to the secondary unwinding station 35.2. Before the transfer, the drive 36.1 of the primary unwinding station coupled to the machine roll is detached from the machine roll. According to the invention, the tension of the web W running from the machine roll 15 to the slitting section 10 is controlled at least partly by a tension control arrangement independent from the rotational position of the machine roll 15. In the embodiment of Figure 2 the tension control arrangement independent from the rotational position of the machine roll comprises a combination of the control system of the actuator 210 and at least the web accumulator 7. Additionally, the control of at least one drive of the winding apparatus 5 illustrated in Figure 1 can be used if necessary. Then, during the transfer, the machine roll 15 is transferred away from the primary unwinding station 35.1 substantially undriven and the tension of the web W of the machine roll 15 is controlled mainly by means of the web accumulator 7. When the tension of the web decreases, the length of the web in the web accumulator is increased and thus more web W is stored in the web accumulator 7, and when the web tension increases the length of the web in the web accumulator is decreased. In this way the changing length of the web during the machine roll change is compensated by turning the levers of the web accumulator. Thus, no separate movable drive following the machine roll is needed for the transfer of the machine roll 15 and compensation of the change in the web length and/or tension can be taken care of in a simple and reliable way.

[0040] The accuracy of the web tension control may be improved by providing the arrangement with a web tension measurement 72 which is here disposed in connection with the guide roll. Now the control of the drives of the winding apparatus 5 can use the real value of the web tension. In the adjustment of the tension, preferably also the impacts of the set ending/change are considered and the requirements of the adhesion of the web layers possibly used in the production of customer rolls.

[0041] Also in the embodiment illustrated in Figure 2 the transfer of the machine roll comprises, due to machine geometry and the web unwinding direction, a phase in which the path of the web from the machine roll to the winding apparatus 5 at first decreases and them starts to increase while the transfer progresses. Then the web unwinding from the machine roll meets the guide roll 70 on the left in the figure, which bends the path of the web while the transfer proceeds and thus increases the length of the web from the machine roll 15 to the winding apparatus. In this situation the web accumulator is according to the invention guided so that the length of the web path induced by the web accumulator 7 decreases.

[0042] Figure 3 illustrates schematically a web slitter winder 1 according to yet another embodiment of the invention. It also comprises a winding apparatus 5 for partial webs, a slitting section 10, and an unwinding apparatus 20 for machine rolls 15 as seen from the side. The structure and operation of these correspond to the components of the embodiment of the slitter winder illustrated in Figure 1. The drives of the primary unwinding station 35.1 and the secondary unwinding station 35.2 have been provided with a motor and a coupling, via which the motor may be coupled with the winding shaft of the machine roll.

[0043] Web W is guided from the machine roll via the slitting section 10 to the winding section 5 guided by the guide rolls 70 of the web. In the manner of Figure 1 , also in this embodiment a web splicing apparatus 60 has been provided in the web transfer portion between the web unwinding apparatus 20 and the slitting section 10.

[0044] In the embodiment of Figure 3 the full-width web W is unwound and slit into partial webs at the slitting section 10 and partial web rolls are wound at the winding apparatus 5. Unwinding is performed in the same way as with the unwinding apparatus of the embodiment in Figure 1. The slitter winder has been equipped with a tension confining means 9 disposed preceding the slitting section 10 in the web running direction. The tension confining means 9 comprises a guard at the web guide roll with which the web may be pressed against the roll and retained between the roll and the tension confining device 9. It is essential that the web cannot slide on the tension confining means. The tension confining means may be steered to contact the roll whereby it is activated and off from the roll whereby it is deactivated.

[0045] There is a control arrangement 200 in connection with the unwinding apparatus provided to guide the operation of the slitter winder, which is here described particularly in connection with the transfer of the machine roll 15 from the primary unwinding station 35.1 to the secondary unwinding station 35.2 as far as the actuator 210 of the support and control apparatus and the tension confining means 9 are concerned. The control arrangement has a data transmission and control connection with the tension confining means 9 and the drives 5.1 and 5.2 and the actuator 210 of the support and control apparatus. [0046] . In Figure 3 the relatively large machine roll in the primary unwinding station 35.1 is depicted by a uniform line. When the size of the roll is adequately small, in other words when the slitter winder has been running sufficiently long, the machine roll 15 is transferred by means of an actuator 210 and a support and control apparatus to the secondary unwinding station 35.2. Before the transfer, the drive 36.1 of the primary unwinding station coupled to the machine roll is detached from the machine roll. According to the invention, the tension of the web W running from the machine roll 15 to the slitting section 10 is controlled particularly at the slitting section at least partly by a tension control arrangement independent from the rotational position of the machine roll 15. In the embodiment of Figure 3 the tension control arrangement independent from the rotational position of the machine roll comprises a combination of the control system of the actuator 210 and the tension confining means 9. Additionally, the solutions described in the Figures 1 and 2 may be employed if necessary. Thus, during the transfer the machine roll 15 is transferred away from the primary unwinding station 35.1 substantially undriven. Prior to the start of the transfer the tension confining means 9 is activated whereby the wire portion following the tension confining means in the web running direction will maintain its tension. In this way a remarkable decrease in the wire tension particularly at the slitting section and thus the possible disturbances caused by the decreasing of the tension can be avoided. The machine roll 15 is transferred from the primary unwinding station to the secondary unwinding station 35.2 and the secondary drive 36.2 is coupled to the machine roll. The machine roll may now be rotated by means of the secondary drive so that the possible slackening of the web during the transfer is compensated before the deactivation of the tension confining means 9. Then a separate movable drive following the machine roll is not needed for the transfer of the machine roll 15. [0047] The machine roll change is preferably performed at least partly during a set change, whereby the web slit during the machine roll change end ends up either to the bottom or the surface of a customer roll. Thus the eventual disturbances cannot cause quality problems inside a customer roll. Preferably the machine roll transfer is performed during the set change preceding the last one. Then the old machine roll 15 becoming empty in the last set change is already at the secondary unwinding station 35.2 and the roll change may be performed particularly quickly.

[0048] Figure 4 illustrates preparation of the splicing taking place after the machine roll transfer. The structure of the slitter winder of Figure 1 corresponds to that of the slitter winder in Figure 1. In connection with the unwinding apparatus 20, a web transfer apparatus 100 has been provided to be moved between the primary unwinding station 35.1 and the vicinity of the web splicing apparatus 60 so that its path 105 passes the guide rolls 70 according to the running of the web W during the normal run. The web transfer apparatus 100 preferably comprises a grip zone as wide as the entire web W. In the embodiment of Figure 4 the web transfer apparatus 100 is a roll or a corresponding member, having a perforated outer surface and connected to a vacuum source 130 and in this way a suction effect may be induced in the perforations of the outer surface of the web transfer apparatus 100. The web transfer apparatus 100 is preferably a suction roll rotatably installed on bearings 110 in the shifting apparatus 120 by means of which it may be transferred along said path 105. The perforation of the outer surface may extend over the whole surface of the roll or over a certain sector of it.

[0049] According to another embodiment of the invention the full-width web W is unwound, and slit at the slitting section to partial webs and partial web rolls are wound at the winding apparatus. The unwinding is started at the primary unwinding station 35.1 and the machine roll 15 is unwound down to a certain diameter after which the machine roll is transferred to the secondary unwinding station 35.2 where the rest of the unwinding of the machine roll is performed. When the web length/tension is in control during the transfer the preparation for the splicing may be performed very quickly.

[0050] At the same time as the final stage of the unwinding of the machine roll is carried out at the secondary unwinding station 35.2, a new machine roll 15 is brought to the primary unwinding station 35.1 and end of the web W of the new machine roll 15 is taken to the vicinity of the splicing apparatus 60 while the unwinding proceeds.

[0051] Figure 4 illustrates a situation where the web transfer apparatus is beginning the transfer of the web W of the new machine roll 15 to the vicinity of the splicing apparatus 60. In the Figure the web transfer apparatus is in contact with the machine roll and the web end has been wound around the web transfer apparatus. When the suction effect of the web transfer apparatus 100 has been switched on the end of the web adheres to the web transfer apparatus 100. The arrangement may comprise also one or several air blast members directed appropriately to assist in this action. The blast may be used to detach or assist in detaching the web from the surface of the machine roll and/or in winding the web to the web transfer apparatus. When the web transfer apparatus 100 is rotated, preferably to a direction in which its surface moves in the unwinding direction of the web, web W is unwound from the machine roll around the web transfer apparatus 100. Figure 4 illustrates with a dashed line the position of the web transfer apparatus, at which the new web is ready for the splicing.

[0052] According to an embodiment the end of the new web is wound to the web transfer apparatus as a strip or a wedge narrower that the web width and the end of the web is taken in full width to the vicinity of the splicing apparatus. For this purpose the unwinding apparatus has preferably been equipped with a wedge cutting device. Subsequently the wedge is spread, simultaneously winding the spreading web wedge around the web transfer apparatus and unwinding web from the primary unwinding station until the new web has reached its full width at the splicing apparatus. This is performed while the unwinding of the old web is in progress at the secondary unwinding station.

[0053] According to another embodiment the end of the new web may be wound in full width at the web transfer apparatus and the end of the web may be transferred in a strip to the vicinity of the splicing apparatus. Also this is performed while the unwinding of the old web is in progress at the secondary unwinding station.

[0054] When the splicing is finished the web transfer apparatus 100 stays under the web. Then the web wound to the web transfer apparatus 100 in connection with the web end transfer can be discharged out without any essential risk of the web being discharged ending up as a disturbance factor to contact the web being unwound. Thus, the web transfer apparatus is preferably discharged empty while the slitter winder is running.

[0055] Although the embodiment examples presented above in the figures describe a so-called above-running application it is applicable also in so-called below-running applications.

[0056] Further, it must be understood that only a few most preferred embodiments of the invention have been presented above. Thus it is obvious that the invention is not limited to the embodiments disclosed above but may be modified in many ways within the scope of protection defined by the appended patent claims. Further, the features presented in connection with the various embodiments may be used in connection with other embodiments within the inventive concept of the invention and/or various entities may be combined from the features presented if desired and the technical possibilities for that exist.

Claims

We claim:

1. A method in connection with a slitter winder (1) according to which method web (W) slit at the slitting section of a slitter winder into partial webs is wound into partial web rolls having a certain diameter and according to which method the machine roll (15) to be unwound is unwound at the primary unwinding station (35.1 ) by a drive (36.1) connected to the machine roll down to a certain diameter, the machine roll is transferred from the primary unwinding station (35.1), characterized in that the tension of the web between machine roll and the winding section is controlled during said transfer mainly by a tension control arrangement (5, 7, 9) independent from the rotational position of the machine roll.

2. A method according to claim 1 , characterized in that the machine roll is released from the primary unwinding station and transferred away from the primary unwinding station so that the rotation of the machine roll (15) is essentially prevented by form locking (36.3)

3. A method according to claim 1 , characterized in that during said transfer of the machine roll (15) the tension of the web is controlled at least partly by means of the winding-up (5) of the slitter winder.

4. A method according to claim 1 or 3, characterized in that during said transfer of the machine web the tension of the machine roll web is controlled at least partly by means of one or several web accumulator/s (7).

5. A method according to claim 1 , 3 or 4, characterized in that during said transfer of the machine roll (15) the tension of the web of the machine roll is controlled at least partly by means of one or several tension confining means (9).

6. A method according to any of the preceding claims, characterized in that the transfer of the machine roll (15) is performed at least partly during a set change.

7. A method according to claim 1 , characterized in that according to the method the machine roll is moved in an essentially horizontal movement away from the primary unwinding station to the secondary unwinding station (35.2) where the final stage of the unwinding of the machine roll is performed.

8. A method according to claim 7, characterized in that at the same time as said final stage of the unwinding of the machine roll is carried out a new machine roll (15) is brought to the primary unwinding station (35.1) and that the web end of the new machine roll is taken to the vicinity of the splicing apparatus (60) while the unwinding is in progress.

9. A method according to claim 8, characterized in that the end of the web of the new machine roll is taken essentially in full width to the vicinity of the splicing apparatus (60) while the unwinding is in progress.

10. A method according to claim 7, characterized in that when the unwinding of the web of the machine roll has been finished the splicing of the web to the web of the new machine roll brought to the vicinity of the splicing apparatus while the unwinding is in progress is carried out.

11. A method according to claim 7, characterized in that the machine roll (15) is transferred from the primary unwinding station to the secondary unwinding station (35.2) essentially during the set change preceding the change of the machine roll.