[001] The present invention relates to a method according to the preamble of patent claim 1 associated with a slitter winder for a fiber web, according to which method a web slit in the slitting section of a slitter winder into partial webs is rewound into partial rolls having a certain diameter and according to which method 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 removed 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 rewound 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 rewinding a new set. These stages are repeated in cycles until paper runs out from the machine roll, whereby the reel 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 rewinding 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 rewinding 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 joined 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.

[004] In an unwinding solution of another type the change of reel is carried out so that the old nearly empty reel is lifted off from the unwinding station so that a new reel can be brought to the unwinding station. A drawback with the solutions of this type known in the prior art is the decrease of capacity caused by the time consumed by the reel change.

[005] Prior art also knows solutions for effecting continuously operating unwinding. US publication no. 6386477 discloses an unwinding system which comprises two unwinding stations provided with integrated drives of their own, and a movable auxiliary drive. The movable drive allows maintaining web tension while the reel being unwound is transferred from the primary unwinding station to the secondary unwinding station. According to the publication the unwinding of a full reel is carried out at the primary unwinding station down to a certain roll diameter after which the reel is transferred to the secondary unwinding station for unwinding and a new full reel is brought to the primary unwinding station. Splicing the web, in other words changing the web to be unwound from the old reel to the new reel has been described as a so-called flying splice, where the end of the new web is connected to the running old web and the old web is severed at normal running speed. A drawback of this kind of an arrangement is that the splicing procedure described in the publication presupposes preparing the machine roll for the flying splice. The flying splice requires a tape in the new reel that secures the outer surface of the web end to the moving old web when these are places face to face during the joining. Further, the taping must keep the new machine roll unwound during the acceleration of the machine roll to the joining velocity. Also, a tape-based flying splicing is almost impossible to effect so that the quality required for further processing like converting is reached.

[006] 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 is minimized.

[007] The objectives of the invention are achieved with the solutions presented in patent claim 1 and more closely in the other patent claims.

[008] According to a preferred embodiment of the present invention the web slit into partial webs at the slitting section of the slitter winder is rewound 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. Subsequently the machine roll is transferred from the primary unwinding station, and during the transfer the tension of the web is at least partly controlled by the drive of the transfer means of the unwinding apparatus and/or by means of a brake device and, after the transfer, a new machine roll is brought to the primary unwinding station. The end of the web of the new machine roll is taken to the vicinity of the splicing apparatus while the unwinding from the old machine roll is in progress.

[009] The machine roll is transferred from the primary unwinding station preferably at least partly during the set change. More advantageously the machine roll is transferred from the primary unwinding station essentially during the set change preceding the machine roll change. The tension of the web is more easily controlled during a set change.

[0010] The machine roll is removed from the primary unwinding station essentially in a horizontal movement to the secondary unwinding station and the final stage of the unwinding of the machine roll is performed in the secondary unwinding station.

[0011] The end of a new machine roll is taken to the vicinity of the splicing apparatus while the previous unwinding is still in progress. According to a preferred embodiment the end of the web is transferred essentially in full width of the web.

[0012] According to another embodiment the joining of the web to the web of the new machine roll brought during the unwinding to the vicinity of the splicing apparatus is carried out at a velocity different from the zero velocity. When the splicing is carried out so that, simultaneously as the webs coming from the secondary unwinding station and the primary unwinding station are joined together, the unwinding is performed at a speed different from zero speed, the joint becomes slanted in the direction of the web running direction which is a joint acceptable for further processing, i.e. a so-called commercial splice.

[0013] According to another embodiment the splicing of the web to the web of a new reel brought during the unwinding to the vicinity of the splicing apparatus is performed when the unwinding of the web in the secondary unwinding station is finished or is about to be finished.

[0014] Numerous advantages are achieved with the invention. The method remarkably improves the overall efficiency of the slitter winder as the operation sequences of the slitter winder are efficiently made more compact and a minimum time is required for splicing the webs during a machine roll change.

[0015] The invention and its operations are described below with reference to the appended schematic drawing figures of which

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

Fig. 2 illustrates schematically a method phase at the slitter winder of Fig. 1 , Fig. 3 illustrates schematically another method phase at the slitter winder of Fig. 1.

[0016] Figure 1 illustrates schematically a slitter winder 1 according to an embodiment of the invention. It comprises a rewinding 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 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 whereby moving even the large roll to be unwound is as simple as possible. 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 preferably an stationary drive 36.1 , 36.2. Both the primary and the secondary unwinding station have a locking device (not illustrated) for the machine roll for locking the unwinding machine roll to the unwinding station. 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 while it is in the unwinding station.

[0017] The rewinding apparatus 5 is in this embodiment a carrier roll/belt winder but it is obvious that the rewinding apparatus can be of any type suitable for rewinding partial webs. Further, the rewinding 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. The rewinding apparatus 5 is used to simultaneously rewind partial webs slit from a full-width web into customer rolls. When the rolls of the set of customer rolls have been wound to the desired size, a so-called set change is performed where the full rolls are removed from the rewinding apparatus 5 and winding of new rolls, the so-called set, is started.

[0018] The unwinding apparatus 20 comprises transfer equipment 40 which engages the machine roll during the transfer on rails 30 so that the movement and the position of the machine roll is determined by the transfer equipment 40. The transfer equipment has been furnished in connection with a rail 45.1 supported on the body 25, the transfer equipment 40 being arranged to be moved along said rail for example by means of a hydraulic actuator (not illustrated). The movement range of the transfer equipment extends from the primary unwinding station 35.1 to the secondary unwinding station 35.2. In connection with the transfer equipment, there is a drive and/or brake device 36.3 provided at the unwinding section on the opposite side compared with the drives 36.1 , 36.2 of the primary and the secondary unwinding stations. The drive and/or brake device 36.3 is arranged to follow the transfer equipment while it moves, which permits controlling the tension of the web by means of said drive during the transfer of the machine roll. In this context the drive and/or braked device associated with the transfer equipment can be simply called a drive. The drive can in some embodiments be a simple brake means or a combination of a drive and a brake. The brake means can also be for example mechanical or electric.

[0019] Web W is guided from the machine roll via the slitting section to the rewinding 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 successively 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 operation of the slitter winder the elements of the web splicing apparatus are situated at a distance from each other but for the jointing operation they are brought together, leaving the webs to be joined between the elements of the splicing apparatus. According to an embodiment of the invention the joining is carried out so that at the same time as the webs arriving from the secondary unwinding station 35.2 and the primary unwinding station 35.1 are being joined together at the splicing apparatus 60, the unwinding is performed at a speed different from zero speed. Then the joint becomes slanted in relation to the running direction of the web, which is a connection suitable for further processing, i.e. a co-called commercial splice. [0020] In connection with the unwinding apparatus 20, there is provided a web transfer device 100 to move between the primary unwinding station 35.1 and the vicinity of the web splicing apparatus 60 so that its path 105 passes by the guide rolls 70 according to the progress of the web W normal run. The web transfer device 100 preferably comprises an adhesion area as wide as the entire web. In the embodiment of Fig. 1 the web transfer device 100 is a roll or a corresponding member perforated at its outer surface and connected to a negative pressure source 130 and thus, a suction effect may be created in the perforations of the outer surface of the web transfer device. The web transfer device 100 is preferably a suction roll. The web transfer device 100 is rotatably mounted on bearings 110 to a shifting apparatus 120 by means of which it can be transferred along the path 105 mentioned. The perforation of the outer surface can extend either over the entire roll surface or over a certain sector of the surface, only.

[0021] According to an embodiment of the invention the full-width web W is unwound at the slitter-winder, slit to partial webs at the slitting section and partial web rolls are rewound at a rewinding apparatus. 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, where the rest of the unwinding of the machine roll is carried out.

[0022] The transfer is carried out so that a drive change is performed at the primary unwinding station 35.1. A transfer device 40 is brought to the machine roll and connected to it. The drive 36.3 of the transfer device is connected also to the machine roll winding shaft and the drive of the primary unwinding station 36.1 is disconnected. Now the transfer device can start transferring the unwinding machine roll towards the secondary unwinding station 35.2. Figure 2 illustrates this situation. The transfer takes place preferably simultaneously with a set change whereby the control of the tension of the web being unwound is simply accomplished by means of the drive 36.3 of the transfer device. The machine roll is transferred to the secondary unwinding station 35.2 and the drive 36.2 of the secondary unwinding station is coupled thereto and the drive of the transfer device can be disconnected.

[0023] As the drive/brake device 36.3 is connected to the machine roll during the transfer, even a great mass can be efficiently controlled. Thus, according to a preferred embodiment, the machine roll 15 is transferred from the primary unwinding station 35.1 to the secondary unwinding station 35.2 essentially during the set change preceding the change of the machine roll 15. Then the old machine roll has been transferred well in time away from the primary unwinding station when the machine roll change starts.

[0024] The control of the web tension preferably also takes into account the influence of the set end/set change and also the requirements of the adhesions of the web layers possibly employed when producing customer rolls.

[0025] In the method stage illustrated in Figure 3 the end portion of the machine roll is being unwound in the secondary unwinding station 35.2 and a new machine roll 15 has been brought to the primary unwinding station 35.1.

[0026] At the same time as said machine roll end portion is being unwound, the end of the new machine roll web W is brought to the vicinity of the splicing apparatus while the unwinding is in progress. The unwinding in the secondary unwinding station is performed so that the tension of the web is controlled by means of the drive 36.2 of the secondary unwinding station. When the transfer device 40 has been provided with a drive so that the machine roll 15 is driven during the transfer, it is not necessary to provide mechanical means for compensating the change in the web length and there is space for the web transfer device according to the invention to operate as the following description discloses.

[0027] Figure 3 illustrates a situation where the transfer of the web W of a new machine roll 15 to the vicinity of the web joining station 60 is about to be started with the web transfer device 100. When the suction of the web transfer device 100 has been switched on and it has been brought to contact the surface of the roll the end of the web adheres to the web transfer device. The arrangement may further include one or several air blow devices appropriately directed to assist this action. The blast can be used to detach the web or to assist in detaching the web from the surface of the machine roll and/or in winding of the web to the web transfer device. When the web transfer device 100 is rotated preferably in the direction that its surface moves in the web unwinding direction, web W is unwound from the machine roll around the web transfer device. At the same time the machine roll 15 is unwound.

[0028] According to an embodiment, the end of the new web is likewise wound to the web transfer device 100 as a strip or a wedge narrower that the web width and the end of the web is transferred in full width to the vicinity of the joining station. For this purpose the unwinding apparatus has been provided with an automatic wedge cutting device (not illustrated). After this the wedge is spread while simultaneously winding the widening web wedge around the web transfer device and unwinding web from the primary unwinding station until the new web has reached full width at the splicing apparatus. This is performed while the old web is being unwound in the secondary unwinding station.

[0029] According to another embodiment, the end of the web can be wound in full width at the web transfer apparatus and transferred as a strip to the vicinity of the joining station. Also this is performed while the old web is being unwound in the secondary unwinding station.

[0030] When the joining has taken place the web transfer apparatus 100 remains under the web. Then the web wound to the web transfer apparatus 100 in connection with the web end transfer can be discarged 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 operating.

[0031] Figure 3 illustrates with a broken line the position of the web transfer apparatus where the unwinding is in progress at the secondary unwinding station 35.2 and the web W from the primary unwinding station has been brought to the vicinity of the splicing apparatus 60. The end W of the new machine roll is automatically brought from the primary unwinding station to the vicinity of the splicing apparatus essentially in full width. Now, essentially immediately after the running of the web from the secondary unwinding station 35.2 ends or is about to end, or it is desirable for some other reason to start winding from the machine roll 15 in the primary unwinding station 35.1 and the slitting and the running of the web W are stopped, the joining of the new web W brought to the vicinity of the splicing apparatus and the old web W is performed at the latest while the web is stopping. After this the slitting can be restarted by unwinding web from the primary unwinding station 35.1.

[0032] When the unwinding of the web during the slitting takes place from the machine roll 15, which is in the primary unwinding station 35.1 , the end of the web wound to the web transfer apparatus 100 can safely be removed from the web transfer apparatus as it is taken past the splicing apparatus under the web running path. When it is now situated under the running web the discharge of the web from the web transfer apparatus can easily and safely be made to a pulper or a broke conveyor underneath.

[0033] The invention may be modified so that the second unwinding station does not have a stationary drive 36.2 of its own at all but the drive of the machine roll and the control of the unwinding process, in other words the control of the tension of the web being unwound is performed at the secondary unwinding station by the drive 36.3 of the transfer apparatus. Then the apparatus and the method carrying it out is even more simple. The drive 36.3 of the transfer apparatus is preferably smaller than the drive 36.1 of the primary unwinding station but the mass of the machine roll in the secondary unwinding station is always smaller than that of the machine roll in the primary unwinding station, whereby an arrangement of this kind is applicable.

[0034] Although the embodiment example presented above describes a so- called above-running application it is applicable in so-called below-running applications. [0035] 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. The features described in conjunction with the different embodiments may be used in conjunction with other embodiments as well and/or various combinations of the described features may be made within the frame of the basic idea of the invention, if so desired and if technical feasibility for this exists.