TRIM STRIP SLITTING AND REMOVAL ARRANGEMENT AND METHOD OF TRIM STRIP SLITTING AND REMOVAL

The present invention relates to a trim strip slitting and removal arrangement according to the preamble of claim 1 for slitting an edge strip from a fibrous web and removing thereof from the running web, which slitting and removal arrangement comprises an edge strip trimmer and a supporting device for the edge strip adapted at a distance from the slitting point of the trimmer in the running direction of the trim strip. The invention also relates to a method of trim strip slitting and removal according to the preamble of claim 14 for cutting and removing of an edge strip from a running fibrous web, in which method the edge strip is slit from the fibrous web by an edge strip trimmer and the run of the edge strip in the running direction of the web is supported after the slitting by a supporting device and the edge strip is removed from the run of the fibrous web at a distance from the slitting point by diverting its running direction by means of the supporting device.

Most preferably, the invention relates to trim strip slitting and removal in conjunction with web slitting and to a trim strip slitting and removal apparatus in conjunction with a slitter-winder. Efficient removal of the trim strip is of crucial importance for successful trimming. Poorly organised strip removal is reason enough for not being able to run the slitter-winder at full capacity. It is important to be able to remove the trim strip at the same velocity as to slit the web in order to get the strip away from cumbering the slitting procedure.

In case the trim strip is relatively narrow, it may well be carried away by using conventional suction nozzles arranged in the immediate vicinity of trimming blades and connected to a removal system. The removal system provides the suction nozzles with suction, by means of which the trim strip

is led to the removal system. In case the width of the trim strip is larger, this kind of transport based solely on the use of air is no longer technically expedient, since it eventually would result in the use of very large ducts and thus also in a very strong air flow. In practise, the whole apparatus would be far too large in terms of its size and energy consumption.

With traditional suction-based systems also the tension of the trim strip, and especially the control thereof, such as the alignment and position, in the trimming and removal process is poorly controllable. In particular, it is important to control the tension difference between the trim strip and the fibrous web going onward in the process in order to achieve successful trimming.

From the publication US 2006/0248995 it is known to provide the cutting unit of a slitter with a supporting section, which supports the cut material web and the strip in the transport direction, when these are transported away from the cutting unit. In this case the supporting section is arranged after the cutting section in the running direction of the material web. According to the publication, the supporting section is a roll or a belt, which extends to the region of both the cut material web and the strip. In this disclosed solution the run of the trim strip cannot be affected irrespective of the run of the material web, whereby its usability is not sufficient in all respects. Both the lateral guidance of the trim strip and the increase of the strip tension alone are, among other things, impossible.

From the publication US 4410315 a trim removal means is known, where a support wheel is arranged in conjunction with a web trimming unit, which wheel supports the trimmed strip from below at the trimming point, and a second wheel spaced apart from the support wheel so that the trim strip is guided between the wheels and led to a trim chute. Here, the running

direction of the trim strip is changed immediately after the trimming and no draw whatsoever can be applied on the trim strip.

The publication US 6206321 discloses a guide roll adapted after the cutting point in the running direction of the web, and short rolls in connection therewith in the edge region of the web so that the short rolls protrude beyond the trim strip also in the web region. Here, the trim strip is adapted to run a little while in the running direction of the web together with the web through the nip formed by the guide roll and a short roll. According to the disclosure the aim with this arrangement is to transmit the web tension also to the trim strip. Neither in this solution the run of the trim strip can be affected irrespective of the run of the material web, whereby its usability is not sufficient in all respects. The lateral guidance of the trim strip, among other things, is not possible.

An object of the present invention is to provide a trim strip removal arrangement and method, by which the harmful effects of trim removal on the slitting process are considerably reduced.

To solve and eliminate e.g. the above-mentioned problems and disadvantages a new type of trim strip slitting and removal arrangement and method have been developed.

A trim strip slitting and removal arrangement according to an embodiment of the invention for slitting an trim strip from a fibrous web and removing thereof from the running web comprises an edge strip trimmer and a supporting device for the edge strip adapted at a distance from the slitting point of the edge strip trimmer in the running direction of the trim strip, in which the supporting device is adapted in transverse direction relative to the running direction of the web in the region of the slitting point on the trim strip's side. It is characteristic of the trim strip slitting and removal

arrangement that the supporting device comprises means for providing controllable draw to the trim strip.

A trim strip slit in this manner can be supported and guided independently, substantially irrespective of the run of the wide fibrous web, whereby the slitting conditions may be optimised more accurately.

The supporting device comprises means for changing the running direction of the trim strip. This makes it possible to guide the run of the trim strip in lateral direction. Especially when the tension profile of the trim strip is oblique and therefore the trim strip has a tendency to diverge in the lateral direction, it is possible to compensate this by guidance provided by the supporting device. In this manner, the run of the trim strip is not allowed to disturb the run of the fibrous web.

The supporting device comprises a supporting surface movable substantially in the running direction of the web, and the supporting surface is arranged flush with the fibrous web thus enabling the run of the trim strip on the same level with the fibrous web between the slitting point and the supporting device. The supporting surface may be a supporting belt loop or fabric loop arranged to run around the rolls. Preferably, however, it is a roll, whereby the space required is considerably small.

The means for providing draw comprise a power unit, for instance an electric motor, in force transmission connection with the supporting device.

In an embodiment, a transport passage for the trim strip is adapted in conjunction with the supporting device, the edge of one end of which passage coincides with clearance with the surface of the supporting device. Further, a pulp conveyor is arranged in conjunction with the transport passage, at the other end thereof, whereby the system for

carrying away the trim strip comprises a combination of a transport passage and a pulp conveyor.

In the method of trim strip slitting and removal for slitting and removing of an edge strip from a running fibrous web, an edge strip is slit from the fibrous web by an edge trimmer and the run of the edge strip in the running direction of the web is supported after the slitting by a supporting device, and the edge strip is removed from the run of the fibrous web at a distance from the slitting point by diverting its running direction by means of the supporting device and run of the trim strip being supported irrespective of the web run. The method is primarily characterised by the trim strip between the slitting point and the support device being subjected to controllable draw via the supporting device.

Preferably, the draw provided for the trim strip by the supporting device is controlled by determining the tension of the fibrous web and by setting on the basis of the tension measurement of the fibrous web a controlled variable for the draw applied on the trim strip by the drive of the supporting device.

The trim strip is removed from the web run at a distance from the slitting point guided by the supporting device. The trimmed edges of the strip and the fibrous web are, when necessary, kept apart from each other after the slitting point by controlling the supporting device, whereby the trim strip and the wide fibrous web do not hamper the run of one another. Especially when the tension profile of the trim strip is oblique, and therefore the trim strip has a tendency to diverge in the lateral direction, it is possible to compensate this by the guidance provided by the supporting device.

The supporting device is provided with a drive, by which a certain torque is exerted on the supporting device and thereby also the trim strip is subject

to an independently adjustable and controlled draw and tension. The drive of the supporting device is preferably controlled by determining the tension of the fibrous web by a separate tension measuring device, which is connection with a control device. By the control device the drive of the supporting device is controlled so that the roll is subjected to a torque providing a tension preferably corresponding to the tension of the fibrous web.

Other characteristic features of the method and apparatus according to the invention are disclosed in the appended claims.

For instance following advantages are achieved by the present invention: it does not require a vacuum-operated transport system, it enables reliable slitting and removal of even a wide trim strip, - it enables a reliable trim strip slitting process.

In the following, the invention and its operation will be explained with reference to the appended schematic drawings, of which Figure 1 shows a side view of an apparatus according to one preferred embodiment of the invention,

Figure 2 shows the apparatus according to Figure 1 seen from direction A, Figure 3 shows another embodiment according to the invention, and Figure 4 shows a detail of the transport passage according to Figure 3.

Figures 1 and 2 show a trim strip slitting and removal arrangement according to an embodiment of the invention adapted in conjunction with a paper web slitter-winder (not shown in the figures). In this context the paper web is mostly called a fibrous web, since the apparatus and method according to the invention are also applicable for handling other kinds of fibrous webs.

The apparatus according to Figures 1 and 2 comprises an edge strip slitter 10 and in conjunction therewith a supporting device 15 for the edge strip. In this embodiment, a wide fibrous web W (may be of full width or cut into partial webs or to be cut into partial webs in conjunction with trimming) is led via two guide rolls 12 along its own path, and during the transfer between the guide rolls 12 an edge strip W is slit from the wide fibrous web W and removed from the run of the web W. The slitting device 10 is in this embodiment a prior art device based on roller blades 14. Naturally, the slitting technique may be realised also in another way. In this embodiment the supporting device 15 for the trim strip is a roll. The roll 15 is adapted in the running direction of the web W at a distance from the slitting point of the slitting device. Being arranged in this manner, the roll supports the trim strip so that it runs as undisturbed as possible from the slitting point to the roll keeping its direction essentially unchanged. On the roll 15, the running direction of the trim strip is diverted from the running direction of the web, whereby the trim strip is separated and removed from the web run. To support and secure the run of the trim strip between the slitting device 10 and the supporting device 15 a plate or the like 17 may be provided.

The edge of the roll 15 facing the fibrous web W is adapted in transverse direction relative to the running direction of the web W, substantially at the slitting point, and it extends from the slitting point far enough to support the trim strip over its whole width. In order to achieve undisturbed operation during the slitting and removal of the trim strip, the distance between the slitting point and the roll 15 in the running direction of the web is according to the invention preferably about 5 - 20 cm, depending e.g. on the running speed, the grade of the fibrous web and the slitting technique. Further, the roll 15 is adapted so that the outer surface 16 of its shell is substantially flush with the plane connecting the surfaces of the guide rolls 12. Thus, the direction of the plane of trim strip coincides with the direction of the plane of the fibrous web also after the slitting right up to the roll 15. In this

manner, also a particularly wide edge strip can be slit and removed undisturbed. Even an edge strip with a width up to 300 mm can be cut by the present apparatus.

The roll 15 is provided with a drive 18, which is in force transmission connection with the roll and by which a certain torque can be exerted on the roll 15 and thereby also the trim strip can be subjected to an independently adjustable and controlled draw and tension. The drive 18 of the roll is preferably controlled by determining the tension of the fibrous web by a separate tension measuring device 22, which is connection with a control device 20. The control device 20 controls the drive of the roll 15 so that the roll is subjected to a torque providing a tension preferably corresponding to the tension of the fibrous web. The position of the tension measuring device may, in practise, also differ from the one shown in Figures 1 and 2. In practise, the value measured by the tension measuring device of the slitter-winder may be used as tension data. Since the tension measuring device 22 defines the tension profile of the web over the its whole width, the reference value for the control of the drive will be precisely the web tension prevailing in the vicinity of the slitting point. Thus, the change of tension over the slitting point in the running direction of the fibrous web is minimal.

In the embodiment according to Figures 1 and 2 the roll 15 is provided with circumferential grooving 24 on the outer surface of the roll shell. The bottom of each groove is provided with holes 26, which open into an inner space 28 enclosed by the roll shell. The roll is preferably a so-called tube roll, whereby it comprises ends and a shell connecting the ends. The inner space 28 of the roll is in connection with a vacuum source 30, which in the present embodiment comprises ducts 32 and a fan 34 arranged therein, which fan sucks air through the holes 26 into the inner space 28 of the roll and out of there thus creating a vacuum, relative to the ambient pressure,

in the inner space 28 of the roll. By means of the vacuum the slitted strip can be made to adhere to the roll surface to such an extent that the torque of the roll can be transmitted to the trim strip to produce a draw of suitable magnitude, whereby the tension of the trim strip can be maintained independently. The grooving distributes the vacuum effect through the holes to a larger area. In some cases, however, e.g. with lighter grades, a sufficient vacuum effect can be provided also without grooving, i.e. merely by means of a perforated roll connected to a vacuum source. It is further possible that with some web types a sufficient adhesion can be provided for the trim strip solely by grooving or by another suitable surface treatment method and/or material.

When the tension profile of the trim strip W is oblique and due to that the trim strip has a tendency to diverge in the lateral direction, it is possible to compensate this by the guiding effect provided by the supporting device. This compensating transfer of the trimmed strip W in transverse direction relative to the running direction of the web is provided by a roll turning device 42 arranged in conjunction with the roll 15. By means of the turning device 42 the roll 15 may be turned relative to the running direction of the web W, which diverts also the running direction of the trim strip on its surface level.

A relatively short transport passage 40 is arranged in conjunction with the roll 15, to which passage the trim strip is led from the roll. The end of the transport passage 40 facing the roll is shaped so that its edge coincides with clearance the surface of the roll 15. Only a relatively small gap remains between these two to enable a contact-free rotation of the roll with respect to the transport passage. Further in the embodiment of Figure 1 , a pulp conveyor 100 is arranged in the trim strip removal system in conjunction with the transport passage 40. The transport passage 40 extends from the roll 15 to the pulp conveyor 100 and the trim strip W is

carried away from the transport passage 40 onward by the pulp conveyor 100.

The pulp conveyor 100 comprises a chute 110, in conjunction with the upper end of which the transport passage is adapted. Further, the chute 110 is in connection with a pulper 150 underneath it. A pulp feed conduit 120 is arranged in the upper part of the chute. The pulp feed conduit is in this embodiment connected to the pulper 150 via piping 130 and the piping 130 is provided at least with a pump. By this arrangement the paper stock in the pulper is transported by the pump 140 along the piping 130 to the feed conduit 120. The pulp feed conduit 120 feeds pulp to the sloping surface of the chute 110 and the pulp flows along the surface down to the pulper. From the roll, the trim strip W is preferably led almost vertically downwards along the relatively short transport passage 40 to the pulp conveyor 100. The trim strip is allowed to fold in the transport passage and it advances assisted by the kinetic energy received from the roll 15 and gravitation through the transport passage 40. When the trimmed strip W comes along the transport passage 40 to the chute 110 and reaches the pulp flowing on its surface, it is caught by the pulp flow, which entrains the strip W to the pulper. Thus, the system according to the invention comprises an above-described combination of a transport passage and a pulp conveyor. This is can be used with much advantage particularly for arranging the transport of a wide trim strip.

Figure 3 depicts an arrangement corresponding in many respects the embodiment in Figure 1 and therefore the reference numbers of Figure 1 have been used in Figure 3, where applicable. The arrangement of Figure 3 is though different, for one thing, because the roll 15 has a different structure. Here, the roll lacks a separate arrangement for providing a vacuum, whereby the solution is somewhat simpler in that respect. The cross-section of the transport passage 40' in conjunction with the roll 15 is

arranged so that it widens in the running direction of the trim strip W, since there are also air feeders 48, 50, 52 connected to the transport passage 40', and this widening shape is advantageous e.g. for the air flow.

In conjunction with the first surface 44 of the transport passage 40' there is provided an air feed arrangement, which in this embodiment comprises an air distribution chamber 46 and a perforation 48 arranged in the surface 44. This first surface is shown in more detail in Figure 4, which will be explained further below. The direction of the first surface 44 of the transport passage 40' coincides with the direction of the rotation axis of the roll. There are also blow nozzles 50, 52 arranged in conjunction with the transport passage, of which the first blow nozzles 50 (there could be one or more in transverse direction relative to the trim strip) are arranged at the end of the transport passage 40' facing the roll 15 so that they blow essentially in the opposite direction with respect to the direction of the roll surface. The air blown from the first blow nozzles 50 loosens the trim strip W running along the surface of the roll 15 from the roll surface and leads it to the transport passage 40'.

The second blow nozzles 52 are adapted along the transport passage, preferably somewhat closer the discharge end of the transport passage than the end facing the roll. The second blow nozzles are directed to blow toward the discharge end of the transport passage, however, at an angle with respect to the transport passage surface, toward the middle area of the cross-section. The air blown from the second blow nozzles prevents steam from raising from the pulper 150 up to the transport passage 40' and also assists with the folding of the trim strip. A pulp conveyor 100 arranged in the chute 110 transports the trim strip to the pulper 150. A pulp feed conduit 120 arranged in the upper part of the chute 110 provides in the chute a pulp conveyor, which catches the trim strip W led to the pulp flow and transports it into the pulper. In Figure 3 there are also knock-

off showers 120' ejecting paper stock and arranged in conjunction with the pulp conveyor thereby enhancing the trim strip being caught and transported by the pulp conveyor. The direction of the knock-off showers is essentially from above toward the flow of the trim strip.

The folding of the trim strip is significant for the operation of the invention to the extent that it enables the pulp conveyor 100 following the transport passage 40' to use a reasonable transport speed. In other words, the running speed of the trim strip is slowed down, when it enters the pulp conveyor 100, by folding the trim strip coming from the transport passage at a higher speed. The transport speed of the trim strip folded on the pulp conveyor is substantially lower than its speed in the transport passage 40'.

The blow nozzles 50, 52 may be in flow connection with the distribution chamber 46 or they may be provided with their respective air sources (not shown in the figures).

The air distribution chamber 46 is provided with an air feed conduit 54, the air blown through which via the holes 48 is supplied from a source 56 of compressed air. The source of compressed air is attached to the feed conduit by a flexible joint, since the first surface 44 of the transport passage 40' and the distribution chamber 46 are in this embodiment movably adapted in connection with the transport passage 40' by means of a pivoting joint 58. The boundary surfaces of the distributing chamber 46 and the transport passage 40' are sealed to a sufficient extent. The pivoting 58 is arranged at the end of the distribution chamber 46 opposite to its end facing the roll 15, whereby the end facing the roll is provided with a power unit 60, such as a hydraulic cylinder. The end of the first surface 44 facing the roll is shaped so that it passes on the roll surface covering it over a certain angle α. Over this section the shape of the first surface corresponds to the outer surface of the roll shell. The section covering the

roll 15 acts as a pressing surface 19 for the roll. The position of the distribution chamber with respect to the roll 15 may be changed by changing the control of the power unit, whereby the distribution chamber has a certain rotational position, while the pivoting joint 58 forms the midpoint of the rotational motion. The power unit can press the section covering the roll 15 against the roll and also loosen it from the roll surface. During normal operation the power unit loads the pressing surface 19 against the roll 15 by desired force, whereby it provides an adhesion effect between the trim strip W and the surface of the roll 15. Through the holes 48 in the first surface compressed air is brought also between the section pressing the trim strip and the running trim strip. In some embodiments the transport passage 40' can be arranged so that it is movable as a whole instead of the distribution chamber only.

The first surface 44 is arranged such that the coefficient of friction between the first surface (at least in the region of the pressing surface 19 covering the roll 15) and the trim strip surface facing the presser is substantially smaller than the coefficient of friction between the surface of the roll 15 and the surface of the trim strip W facing the roll.

Figure 4 shows one preferable array of the holes 48 in the first surface. The holes 48 are aligned in the running direction of the trim strip W (arrow) successively so as to form rows 62 of holes. Stream lines 64, formed by the compressed air between the fast-running trim strip and the surface, use the rows of holes to create a vacuum 66 between the stream lines, which vacuum supports the running of the web to the vicinity of the surface. Using the produced lower pressure the flow lines draw the trim strip W away from the surface of the roll 15 and convey the trim strip to the transport passage 40'. The first surface 44 of the transport passage 40' is curved and, based on the Coanda effect, the stream lines 64 follow the surface and at the same time force also the trim strip to follow the first

surface 44. Figure 3 shows that after the curved section, at the latest, the cross-section of the transport passage is arranged to grow relatively fast, whereby the speed of the air flow is reduced and the folding of the trim strip is started. The folding is enhanced also by the second blow nozzles 52 arranged at latter section of the transport passage. There is enough space for the trim strip to fold at the end of the transport passage and it advances by means of the air nozzles and gravitation to the pulp conveyor.

It is to be noted that only a few most advantageous embodiments of the invention have been described in the above. Thus, it is clear that the invention is not limited to the above-described embodiments, but may be applied in many ways within the frame of the appended claims. The solutions according to the above embodiments are also mutually applicable as long as it is technically feasible.