WO2004018337A1

WO2004018337A1 - Device in connection with a splicing device for a continuous unwind of a fibrous web, in particular a paper or board web

Info

Publication number: WO2004018337A1
Application number: PCT/FI2003/000609
Authority: WO
Inventors: Marko Tiilikainen; Silvo Mikkonen
Original assignee: Metso Paper, Inc.
Priority date: 2002-08-20
Filing date: 2003-08-18
Publication date: 2004-03-04
Also published as: FI20021498L; AU2003251024A1; FI20021498A0

Abstract

The invention relates to a device in connection with a splicing device for a continuous unwind of a fibrous web, in particular a paper or board web, which splicing device comprises a paster roll (12) by means of which a web (W) of an expiring machine reel (11) is pressed into contact with a splice placed on a new machine reel (14). A device (15) is placed in connection with the splicing device on a web run between the paster roll (12) and a subsequent paper guide roll (13) or an equivalent roll guiding the running of the web (W), in connection with which device (15) at least one blow nozzle (16) is formed which extends in the width direction of the web (W) and produces blowings which are arranged to produce air flows stabilizing the running of the web (W) and to cause the web to run via the device (15).

Description

Device in connection with a splicing device for a continuous unwind of a fibrous web, in particular a paper or board web

The invention relates to a device according to the preamble of claim 1.

In off-machine coaters, a continuous unwind is used in which a new machine reel brought to the unwind is joined at full speed to the tail of an expiring machine reel. The end of the web of the new machine reel is prepared with a splice using double-sided adhesive tape, which splice is attached to the surface of the reel by means of pieces of adhesive tape. The surface speed of the new machine reel is accelerated to a speed equal to the running speed of the machine, after which the web of the expiring machine reel is pressed into contact with the above-mentioned splice by means of a roll or a brush. The old web is cut off by means of a knife from above the splice. Today, a paster roll usually having a thick soft rubber surface is generally used as the splicing device of a continuous unwind. The core material of the paster roll is generally steel, but it may also be of some other material, such as, for example, carbon fibre.

Flying splicing in a continuous unwind is described, for example, in the publication Papermaking Science and Technology, Book 11, Pigment Coating and Surface Sizing of Paper, pp. 470-475, Papet Oy, 2000.

The splicing at the unwind has become problematic at today's running speeds (1200 - 1800 m/min). For this reason, the running speed of the coater is often lowerred for the time of splicing. At high running speeds, the most important causes of the problem of splicing are air flows and the required high speed of movement of the paster roll. At high speed, an underpressure is produced in a so- called splicing gap between the paster roll moved to the vicinity and the machine reel, which underpressure may be pulsating if the new machine reel is out-of- round. The underpressure tends to pull the old web partly into contact with the splice even before the splicing operation and cause fluttering of the old web. In addition, the underpressure tends to separate the tape splice from the surface of the new machine reel, so that the new machine reel "explodes" before splicing. In order that the running of the web should be controlled, an angular bend is required at the paster roll, which again calls for stretching of the web when the paster roll is quickly struck against the surface of the new machine reel. The tension peak caused by the hitting of the roll during splicing is attempted to be kept low by using a small splicing gap (8 - 12 mm), which gives rise to an intensive underpressure phenomenon. Even the bend angle used today causes a problematic tension peak in the web. At higher running speeds an even larger bend angle would be required.

Thus, the main problems in the splicing devices of a continuous unwind are the high speed of the stroke of the paster roll, the large bend angle of the web and the underpressure formed in the splicing gap. The underpressure causes harmful fluttering and the possibility of the tape used for splicing becoming separated is very high. When a large splicing gap is used, the risk of web break increases. Likewise, when a large bend angle is used, the risk of web break increases. When the splicing gap is made smaller, the consequence is an increase in underpressure and the resultant adverse effects. When the splicing gap is made larger, the tension peak to which the web is subjected, i.e. the risk of web break, becomes higher.

With respect to the prior art relating to splicing devices for a continuous unwind, reference may be made, for example, to FI patents FI 100323 and FI 96299, which disclose solutions relating to the problems caused by the large bend angle of the web and the underpressure in the splicing gap, as well as arrangements for providing a sufficient adhesion time for a splicing tape to adhere. FI patent 100323 discloses a splicing device for a continuous unwind, by means of which device a new machine reel brought to the unwind is joined at full speed to the web of an expiring machine reel. The splicing device comprises a paster roll, by means of which the web of the expiring machine reel is pressed into contact with a splice on the new machine reel, and at least one second roll. The paster roll and the second roll are attached to a lever device which is mounted by means of an articulation point between shafts of the rolls such that the running of the web before splicing and the running of the web during splicing are such that the length of the web during splicing and when said rolls are in a basic position, is substantially equal. FI patent 96299 discloses a splicing device for a continuous unwind, by means of which device a new machine reel brought to the unwind is joined at full speed to the web of an expiring machine reel, the splicing device comprising a paster roll, by means of which the web of the expiring machine reel is pressed into contact with a splice on the new machine reel, and which splicing device comprises at least one second roll, and in which splicing device the paster roll and said second roll are attached to a lever device which is mounted by means of an articulation point between shafts of said rolls such that the running of the web before splicing and the running of the web during splicing are such that the length of the web during splicing and when said rolls are in a basic position, is substantially equal. A support wire is arranged to run via the paster roll and said second roll to form a wire nip, so that the time of adhesion available for splicing increases manyfold.

One problem in the flying splicing of a coater is the fluttering which occurs under the splicing nip and which limits splicing speeds at speeds exceeding 1500 m/min, and which web fluttering is caused by contacting a moving web and a rotating roll with each other and by air flows moving on the surfaces in question. A throttling area at the splicing point produces an overpressure above it and an underpressure in the area opening under it, where suction is formed, which thus causes fluttering. Because of fluttering, the web unwound before splicing may adhere to splicing tapes, thus preventing successful splicing. On the other hand, after splicing when the paster roll separates from the web that is being unwound, there occurs a momentary intensive fluttering phenomenon, which may cause creases in the web, which creases break the web in a coating station. This fluttering is problematic even though it would be possible to fill the underpressure area situated after the throttling area after the splicing point because air flows around the edges of the web, with the result that the web may curl. In practice, attempts have been made to control the fluttering after splicing by leaving the splicing mechanism and the paster roll in a forward position to support the exiting web, but coating may be damaged in a break after the splice if a large paper clod enters a narrow nip gap when the nip is slightly open. The splicing mechanism is driven backwards only after the roll has decelerated to a sufficient degree because the rotation of the roll brings detrimental air to the fluttering phenomenon after splicing.

Some fluttering also occurs when the expiring reel is being lifted from a lower winding position to an upper winding position, in particular when the unwinding web, while it moves substantially vertically from above downwards, comes into contact with a rotating paster roll. In this tangential situation, the web flutters strongly for a short time.

One object of the invention is to provide solutions to the above-noted problems caused by fluttering.

One problem is also the looseness of surface sheets and its variation and the resultant variation of tension after splicing, which is caused by errors in measuring the diameter of a new reel, by stretching and contracting of surface sheets, which is in turn caused by the variation of hall moisture according to the time of the year and by the storage time of the reel on rails.

An object of the invention is to provide an improvement in the currently known splicing devices for a continuous unwind stand. A more particular object of the invention is to provide a splicing device of a continuous unwind in which the drawbacks encountered in the arrangements of the state of the art are avoided.

The device according to the invention is mainly characterized in what is stated in the characterizing part of claim 1.

In accordance with the invention, a blowing device, advantageously assembled of modules and forming the device according to the invention, is mounted in the region between a paster roll and a paper guide roll across the full width, and advantageously such that the device has several blow zones in succession in a machine direction. The blowing direction of the blow nozzle of the device is opposite or parallel to the running direction of the web or a combination of these.

In one advantageous embodiment of the invention, the modules, i.e guide plates, which have blowing rows formed of blow nozzles, can be unequal or equal in length in the running direction of the web and, when desired, it is possible to use several component modules of unequal or equal width in a direction transverse to the running direction of the web.

The blow units of the device in accordance with the invention, when some of the blowing rows, i.e. of sets of blowing rows, have been activated, draw the web into contact with themselves before splicing, and the fluttering of the web is prevented after splicing by increasing blowing capacity and/or by activating the rest of the sets of blowing rows. At the same time, the surface sheets of the reel being spliced can be tightened and the detrimental tension drop after splicing is eliminated.

By controlling different air supply regions, the blow zones formed by the blowing rows of the device in accordance with the invention can be profiled in respect of tension by means of a variable pressure and/or volumetric flow. The invention provides, among other things, the following benefits:

- fluttering is prevented before and after splicing,

- surface sheets can be tightened after a splice by deflecting the web suitably by means of blowings, - the web can be tightened in a profiling manner, for example, more at the edges.

The modular construction in accordance with an advantageous embodiment of the invention facilitates transportation and mounting.

The device in accordance with the invention can also be used for stabilizing the running of the web temporarily for a few seconds when an expiring reel is being lifted from a lower winding position to an upper winding position, in particular at the moment when an unwinding web comes into contact with the rotating paster roll while moving vertically from above downwards. In this tangential situation, the fluttering of the web is damped down by blowings produced by means of the blowing rows of the device in accordance with the invention.

The device in accordance with the invention is also suitable for use during lifting according to other alternative splicing methods: - the paster roll is stopped, at low speed or crawling,

- under the reel in the vicinity of the floor level there is a substantially full width blowing row that blows against the web in the region between the paster roll and a paper guide roll and simultaneously presses the web into a curve.

The invention is suitable for use advantageously at running speeds exceeding 1200 m/min, in particular at running speeds exceeding 1500 m/min.

In the following, the invention will be described in greater detail in the figures of the appended drawing. Figure 1 is a schematic general view of a continuous unwind in connection with which one advantageous embodiment of the device in accordance with the invention has been placed.

Figure 2 is a schematic view of making use of one embodiment of the device in accordance with the invention when a reel is moved to a secondary winding position while the reel is expiring.

Figure 3 is a schematic view of making use of one embodiment of the device in accordance with the invention for stabilizing the web during winding from a secondary position and during the splicing acceleration of a machine reel to be spliced.

Figure 4 is a schematic view of using one embodiment of the device in accordance with the invention in connection with splicing for tightening a loose surface and for stabilizing the running of the web.

Figure 5 is a schematic view of using one embodiment of the device in accordance with the invention in connection with backing up of the splicing mechanism after splicing.

Figures 6A - 6E schematically show some exemplifying embodiments of the device in accordance with the invention.

Figure 7 is a schematic view of one embodiment of the device in accordance with the invention, which embodiment is formed of a set of guide plates of modular construction.

In Fig. 1, an expiring machine reel is denoted with the reference numeral 11 and a paster roll with the reference numeral 12. A guide roll of a web W preceding the paster roll 12 is denoted with the reference numeral 13 A. The expiring machine reel 11 has been lifted to a secondary winding position and a new machine reel 14 has been brought to a ready position for splicing. The direction of rotation of the expiring machine reel 11 is indicated by the arrow Si i and the direction of rotation of the new machine reel 14 is indicated by the arrow S₁₄. A guide roll of the web W in the mechanism of splicing is denoted with the reference numeral 13. In accordance with the invention, a device 15 in accordance with the invention is placed on the web run between the paster roll 12 and the guide roll 13 of the web W placed after it, which device 15 is formed, in this exemplifying embodiment of the invention, of a set of guide or blowing plates 17, which is modular in construction and comprises blow nozzles 16 placed in a direction transverse to the running direction Sw of the web W. The set of blowing plates 17 of modular construction in accordance with this embodiment of the device in accordance with the invention is thus formed of nozzle structures 16 placed in succession in the running direction of the web and, when desired, of several structures which are placed transversely to the running direction Sw of the web and which are separately adjustable. The nozzle structure 16 may also be continuous in a direction transverse to the running direction Sw of the web W.

The modular embodiment of the device 15 in accordance with the invention is easy to mount in place in mill conditions, and no large uniform plate field is formed which is problematic in respect of its mounting technique.

In accordance with the invention, air is blown from blow nozzles/a blow nozzle 16 of the device 16, whereby the web W can be caused to adhere to and run along the surface of the guide plates 17, so that fluttering after splicing is prevented. Before splicing, a blow nozzle 16 / desired blow nozzles 16 are activated and the fluttering of the web W after splicing is prevented by increasing blowing capacity and/or by activating more blow nozzles 16. The activation of the blow nozzles 16 used can be accomplished such that some of the blow nozzles 16 placed in succession in the running direction S_w of the web and/or some of the blow nozzles 16 situated in a direction transverse to the running direction S of the web W are activated. By controlling different air supply regions, the thus provided blow zones can be profiled in respect of tension by means of a variable pressure and/or the volumetric flow used.

Fig. 2 schematically shows the use of the device 15 in accordance with the invention when an expiring machine reel 11 is being lifted to a secondary winding position 11', which is indicated by the arrow Sy. In Fig. 2, the same reference numerals are used of the parts corresponding to those of Fig. 1. By means of a set of plates 17 of the device 15 and the blowings of blow nozzles 16, the fluttering of the web W is damped down on the web runs W and W and the web W is tightened, so that no detrimental fluttering occurs.

In Fig. 3, reference signs corresponding to those of Figs. 1 and 2 are used of the parts corresponding to one another. In the situation illustrated in Fig. 3, the web W is being passed from an expiring machine reel 11 and a new machine reel 14 is being accelerated to splicing speed, in which connection the web W flutters in the region W_L during splicing acceleration. The web W is caused to run via the device 15 by means of blowings from the blow nozzles 16 of the device 15 in accordance with the invention, whereby fluttering is attenuated.

In Fig. 4, the same reference numerals as in Figs. 1 - 3 are further used of the corresponding parts, and Fig. 4 shows how a surface sheet is tightened and the running of the web W is stabilized by means of blowings of the blow nozzles 16 produced by the device 15 in accordance with the invention during splicing. The web W on the run W_L at the device 15 is guided by means of the blowings of the blow nozzle 16 to run via the device 15, whereby the surface layers of the reel 14 are tightened.

Fig. 5 is a schematic view of a situation where a paster roll 12, a web guide roll 13 of the splicing device and a web guide roll 13A preceding the paster roll 12 are being backed away from the splicing position after splicing. In that connection, the device 15 in accordance with the invention is also backed up from the splicing position and, when needed, blowings that stabilize the running of the web can then be blown from the blow nozzle 16 of the device 15. The transfer movements away from the splicing position after splicing are indicated by the reference arrows S in the figure.

Fig. 6 A is a schematic transverse view of the device 15 in accordance with the invention, placed on the run between a paster roll 12 and a web guide roll 13 of the splicing device. In the figure, the arrows indicate blowings blown from blow nozzles of the device 15 in accordance with the invention for the purpose of stabilizing the running of the web W.

As shown in Fig. 6B, this exemplifying embodiment of the invention does not have a modular construction but is formed of a single, for example, box-like device unit, the blow nozzles 16 of which provide a uniform blowing over the entire width of the web. As described above in connection with other figures, the device in accordance with the invention may also be of sectional construction in a direction transverse to the running direction of the web, so that blowings can also be regulated in the transverse direction of the web.

As shown in Fig. 6C, the device 15 in accordance with the invention may also be a roll, for example, a grooved roll or a roll of a sectional roll construction, which can be provided with a drive or can be without a drive.

Fig. 6D shows an arrangement in accordance with the invention in which a blow nozzle structure 16 is arranged in connection with a spreader bar 15.

Fig. 6D shows an embodiment in which blow nozzles 16 are arranged in connected with a rib-like structure 15. In Figs. 1-5 described above, the trailing edge of each guide plate of the set of guide plates 17 can be rounded, when desired, to remove the air flow coming from the blow nozzle 16 and along with the web W and to remove the counter flow of the web guide roll 13 of the splicing device.

Fig. 7 schematically shows a device arrangement formed of a set of modular guide plates 17 of the device 15 in accordance with the invention, in which arrangement the trailing edge of the plate is provided with a rounding to guide the flow of air.

Only some advantageous embodiments of the invention have been described above, and it is clear to a person skilled in the art that numerous modifications can be made to it within the inventive idea presented in the appended claims.

Claims

1. A device in connection with a splicing device for a continuous unwind of a fibrous web, in particular a paper or board web, which splicing device comprises a paster roll (12) by means of which a web (W) of an expiring machine reel (11) is pressed into contact with a splice placed on a new machine reel (14), characterized in that a device (15) is placed in connection with the splicing device on a web run (W_L) between the paster roll (12) and a subsequent paper guide roll (13) or an equivalent roll guiding the running of the web (W), in connection with which device (15) at least one blow nozzle (16) is formed which extends in the width direction of the web (W) and produces blowings which are arranged to produce air flows stabilizing the running of the web (W) and to cause the web to run via the device (15).

2. A device as claimed in claim 1, characterized in that the device (15) and the blow nozzle/nozzles (16) is/are formed so as to extend substantially over the entire width of the web.

3. A device as claimed in claim 1 or 2, characterized in that the device (15) and the blow nozzle/nozzles (16) is/are formed of several separate modules in the width direction of the web, the blowings of the blow nozzle/nozzles in each module being separately adjustable.

4. A device as claimed in claim 1 or 2, characterized in that the device (15) and the blow nozzle (16) are formed into a continuous unit extending substantially over the entire width of the web.

5. A device as claimed in any one of claims 1 to 4, characterized in that the device (15) is formed of at least two modules (17) placed in succession in the running direction of the web .

6. A device as claimed in any one of claims 1 to 5, characterized in that the blow nozzles of the device (15) can be controlled to adjust blowings in blow zones both in the running direction (Sw) of the web and in the width direction of the web, i.e. in a direction transverse to the running direction of the web.

7. A device as claimed in any one of claims 1 to 6, characterized in that the device (15) is formed of guide plates (17), which are combined modularly to form a unit in the running and width direction of the web.

8. A device as claimed in claim 1, characterized in that each trailing edge of the guide plate (17) is rounded (FIG. 7).

9. A device as claimed in any one of claims 1 to 8, characterized in that the device is arranged to be used to prevent fluttering of the web (W) after the paster roll (12).

10. A device as claimed in any one of claims 1 to 9, characterized in that the device is arranged to be used to prevent fluttering of the web when the expiring machine reel (11) is being lifted up on web runs (WK, W_L) from the expiring machine reel (11) to the paster roll (12) and from the paster roll (12) to the subsequent paper guide roll (13) or an equivalent roll guiding the running of the web.

11. A device as claimed in any one of claims 1 to 10, characterized in that the device is arranged to be used to tighten surface sheets of a new machine reel (14) by means of blowings of the blow nozzles.