WO1999062802A1

WO1999062802A1 - Method and device in supporting of a reel

Info

Publication number: WO1999062802A1
Application number: PCT/FI1999/000454
Authority: WO
Inventors: Seppo Luomi
Original assignee: Valmet Corporation
Priority date: 1998-05-29
Filing date: 1999-05-27
Publication date: 1999-12-09
Also published as: AU4516899A; FI981210A; FI981210A0

Abstract

In the method in supporting of a reel, a full-width web (W) is accumulated to form a machine reel (R), and a force effect lifting the reel (R) is applied to the lower surface of the reel (R) to maintain the reel spool (1) supported at its ends and the reel (R) substantially straight in the horizontal direction. To produce the lifting force, at least one pressurized air pocket (P) is provided against a section of the lower surface of the reel (R), and two side gaps (6) left between the edges of the mantle (5) of the pressurized air pocket (P) parallel to the reel spool (1) and the surface of the reel (R), are sealed with a pressing roll (4) parallel to the reel spool (1), to seal off the pressurized air pocket (P). As a result of the over-pressure produced inside the pressurized air pocket (P), a lifting force effect is excerted on the section of the lower surface of the reel (R).

Description

Method and device in supporting of a reel

The present invention relates to a method in supporting of a reel especially in a continuous reel-up of a paper machine or finishing apparatus for paper, wherein a reel which is being filled with a full-width web is supported to maintain the straightness in the direction of its longitudinal axis. The invention also relates to a device for implementing said method.

In the reel-up of a paper web, hereinafter also shortly the web, a web of several metres in width is reeled around a reeling axle (reel spool) to form a machine reel. The reeling process itself is conducted in such a way that the reeling axle is loaded against the reeling cylinder, and the web to be reeled travels via a nip formed thereby, winding around the reel spool to form a complete reel. The loading is effected by means of force devices, typically by means of hydraulic cylinders, acting on the ends of the reel spool. At the same time, the reel spool is also rotated with a centre-drive. Such machine reels are reeled in the paper machine in the terminal end of the paper making process as well as in the finishing apparatus for paper, e.g. in an off-line coating machine.

The web accumulated onto the reel constantly increases the mass of the reel so that it may be as high as several tonnes at its maximum. Since the reel spool may be 5 to 6 metres wide, or even wider, and the reel spool is arranged to rotate only on supports placed at the ends of its axis, it is obvious that the reel tends to deflect, thereby deflecting the reel spool and its axis downwards between the supports. The deflection stresses the reel spool and makes considerable demands on its structure in view of strength. As a result of said deflection, the contact of the surface of the reel with the reeling cylinder is easily disturbed, because the possible deflection of the reeling cylinder is in any case less significant than the deflection of the reel. The difference between the deflections, which increases constantly when the radius of the reel grows, complicates the process of reeling the web evenly across the whole width of the reel, and weakens the quality of the reel. To eliminate the aforementioned problems, there are several known devices, the purpose of which is to support the reel from below and to keep the reel, the reel spool and its axis as straight as possible. The solutions of known devices are primarily based on the mechanical contact of the device or part of it with the reel or on the use of pressurized air.

As for the solutions forming a contact with the reel, it is possible to mention belts, bands, or the like which support the reel from below. Supports which are based solely on mechanical contact over a long section of the periphery of the reel usually require a belt-drive and a flawless operation of the belt within a width of several meters, and they may produce longitudinal marks into the complete web, which significantly weakens the quality of the finished product especially in the case of fine-surface art papers or the like.

Patent publication US 5647555 discloses a device in the supporting of a reel, which device is solely based on the use of pressurized air in such a way that no mechanical contact of any kind is provided between the reel and the device. An essential part of the device is a pressurized air pocket which is pressed towards a section of the lower surface of the reel. The mantle of the pressurized air pocket is made of flexible material, wherein it adapts itself to the form of the reel according to the changes in the reel radius, when the edges of the pressurized air pocket extending in the width direction of the reel, i.e. the side edges, are pressed towards the reel. The mantle is transferred in its height direction and its side edges are pressed preferably by means of pneumatic or hydraulic actuators located below the pressurized air pocket, so that the side edges and end edges are positioned very close to the surface of the reel. In the pressurized air pocket, over-pressure is generated to produce a force effect which lifts and straightens the reel. The over-pressure is set so that the force effect it produces is sufficient for straightening the reel, but at the same time so that the overpressure is constantly discharged from the side gaps and end gaps between the mantle and the reel to keep the mantle apart from the surface of the reel. Even though the purpose of the described solution clearly is to prevent the development of marks into the reel that is being reeled as a result of the mechanical contact between the machine and the reel, a malfunction of the device may, however, cause the pressing of the mantle against the surface of the reel. Such a malfunction is for example a sudden drop in the air pressure in the pressurized air pocket as a result of a fault in the pressure system, or in a situation when too large an air gap is formed locally into the gaps between the mantle and the reel. The requirements set for the pressure producing system are also considerable, because the production of a sufficiently powerful force effect in order to keep the reel of several tonnes straight, requires a substantial over-pressure in the pressurized air pocket, as it is also necessary to pay attention to the air discharged through the gap of the mantle. The discharged air also causes additional air currents in the peripheral direction in connection with the reel-up.

The purpose of the invention is to present a method by means of which the aforementioned drawbacks related to prior art can be eliminated, thus improving the state of art in the field. To attain this purpose, the method according to the invention in supporting of a reel is primarily characterized in that a lifting force effect is applied to a section of the lower surface of the reel, the force effect being generated with a pressurized air pocket in such a way that in the side gaps (= the gaps in accordance with the width direction of the reel) in the mantle of the pressurized air pocket, rotating pressing rolls are placed to seal the pressurized air pocket. When the end gaps of the mantle are also sealed with separate end seals, a pressurized air pocket is produced from which practically no air is discharged to the environment of the reel-up. At any case, the amount of air discharged at the end seals is smaller than that discharged when the side gaps have a slot extending over the width of the reel. The surfaces of the pressing rolls are formed and the dimensions, positions and drives of the same are arranged in such a way that they do not produce any marks on the web despite the continuous contact.

Furthermore, the purpose of the invention is to present a device in supporting of the reel for using the above-described method. The device is primarily characterized in that the pressurized air pocket comprises a mantle and pressing rolls placed in the side gaps of the same for sealing of the side gaps in particular.

By means of the method and device according to the invention in supporting of a reel, it is possible to enhance the support by loading one or more pressing rolls against the reel, wherein the development of the force effect to be applied to the reel is not solely dependent on the over-pressure prevailing inside the pressurized air pocket. On the other hand, an important task of the over-pressure is, correspondingly, to support the reel throughout a wide area thus reducing the loading effect exerted by the reel on the pressing rolls. The reels can be arranged to rotate with a reel-specific drive or the like. The need to adjust the pressure is substantially solely dependent on the change in the radius of the reel and thus on the change in the mass of the reel, and the support of the reel is based on the use of adjustable pressurized air, wherein the support force is proportional to the surface area of the surface of the reel R located within the range of action of the pocket and the pressure. Thus, in this invention, it is possible to optimize the ratio of the degrees of loading applied to the reel by the over-pressure and the pressing rolls, to generate the most advantageous lifting force effect without damaging the surface of the finished web. The surface area can also be adjusted by changing the distance of the rolls in the direction of the perphery of the reel.

Other characteristic features of the invention will be disclosed in the appended dependent claims.

In the following description, the invention will be described in more detail with reference to the appended drawing. In the drawing, the invention is shown in a schematical side-view.

The drawing shows schematically a paper machine reel-up, a so-called Pope-reel, which reel-up continuously forms paper reels of a full-width web W passed from a paper machine or the like, of which reels the one that is becoming full is marked with the letter R. The rotating reeling cylinder 3, i.e. the Pope-cylinder guides the web W onto the reel R around a reel spool 1 supported at its ends on reeling rails or the like. The reel is loaded in the radial direction against the reeling cylinder 3 by means of loading devices on the other side of the reeling cylinder 3 as seen in the travel direction of the web. The loading devices are known as such and they are not shown in the drawing. The loading is effected by excerting a force effect on the ends of the reel spool 1 by means of force devices such as hydraulic cylinders, which force effect can be transmitted to the ends of the reel spool 1 by means of a suitable mechanism. The reel R is centre-driven, i.e. the reel spool 1 , around which the web W accumulates to form a reel R, is provided with a drive which is marked with the reference numeral 2.

The paper web to be reeled is a full-width web, typically several metres wide. This web is reeled around the same reeling axle to form a machine reel of several tonnes (e.g. over 5 tonnes) in weight, which machine reel can be rereeled later. The machine reel is a kind of a storage reel for accumulating the reel in portions of fixed size from a continuous manufacturing or finishing process. In the end, the web is slit into narrower part webs, which are wound into customer rolls. The full-width web to be reeled has gone through a manufacturing or finishing process in the sections preceding the reel-up, and it is reeled around the reel spool substantially in the manufacturing or finishing width, possibly so that the trims are cut off from the edges. Without restricting the concept of a full-width web solely to certain dimensions, it can be said that the width of such a complete web to be reeled is typically over 3 m, in wider machines in the order of 8 to 10 m.

The reeling nip N that influences the quality of the reel is formed, in the way characteristical of this reel-up type, at the side of the reel R in a point where the web W is guided on top of the preceding layers of the reel, and starts to wind towards the lowermost section of the reel on the reel. The nip N is typically close to the horizontal plane.

The reel R, which tends to deflect downwards in the middle due to the effect of the mass of the web W wound on the same, and at the same time deflects the reel spool 1 and its axis 2, is supported by applying to a section of its lower surface a force effect lifting the reel R. To implement this, a pressurized air pocket P is formed against the section of the lower surface of the reel R within an angular distance therefrom after the reeling nip in the direction of rotation. An over-pressure prevails in the air pocket, thus producing the intended force effect. The section of the lower surface of the reel R can also be substantially equal in width with the reel R in the width direction of the reel R, or also substantially narrower than the reel R. In the peripheral direction, said section i.e. the influence sector of the pressure can vary in accordance with the paper grade, especially its grammage, the size of the reel or otherwise in the most suitable manner required by the situation.

The pressurized air pocket P is composed of a mantle 5, i.e. a wall restricting it outwards, whose open upper part substantially corresponds to the section of the lower surface of the reel R to which the force effect is to be applied. The mantle 5 thus forms the bottom portion as well as the walls of a hollow space, which is covered above with the section of the lower surface of the reel R. This hollow space is provided with over-pressure by means of pneumatic appliances in a way known as such, not shown separately, by passing the over- pressure via a channel 9 led through the mantle.

Between the upper edge of the mantle 5 and the reel R, two side gaps 6, parallel to the width direction of the reel R, as well as two transverse end gaps 7 are formed. For the purpose of sealing the side gaps 6, there are pressing rolls 4 placed along the side gaps 6 of the pressurized air pocket P; according to the preferred embodiment of the drawing, one in each side gap 6. The pressing rolls 4 are advantageously substantially equal in width with the reel R, the width of the mantle 5 being preferably substantially the same. This is advantageous especially because the end gaps 7 formed in the ends of the pressurized air pocket P can be sealed by means of end seals 8, which are arranged to seal off the end gaps 7 particularly against the ends of the reel R, and the end seals 8 cannot thus produce marks onto the surface of the web W. To implement the end seals 8, solutions known as such are used, which will not be discussed in more detail. There may be a larger number of pressing rolls 4 in the side gaps 6 than the total of two presented above. One or both side gaps may be provided with two or more pressing rolls of equal width, but they can also differ from each other in width. Broken lines illustrate auxiliary pressing rolls 4'. It is also possible that the presented pressing roll 4 is composed of several parts successive in the width direction, which cooperate to seal off the side gap 6. The number of pressing rolls can be utilized to influence the tightness of the pressurized air pocket P and the possibilities to support the reel also by means of the pressing rolls, which will be described in more detail in the following.

One pressing roll 4, both pressing rolls (the embodiment of the drawing), some pressing rolls or all pressing rolls may be provided with an arrangement for loading them against the reel R, with the special purpose of dividing the lifting force effect between the pressing rolls and the pressurized air. The loading is preferably adjustable, wherein the pressure produced by the loading against the web W can be changed in accordance with the requirements set each time by the weight of the reel, the paper grade or another corresponding factor. The loading can be arranged by means of known force devices (hydraulic cylinders, pneumatic cylinders) operated by pressurized medium, which force devices load the entire mantle 5 into the direction of the radius of the reel R. With the pressure of the pressurized air pocket P it is also possible to suitably reduce the loading produced by the pressing rolls 4.

The pressing rolls 4 can be freely rotating, effected by the rotation of the reel R, but the applicability of their use in different targets and situations can still be improved by providing one or more pressing rolls 4 with a drive to rotate the same. By adapting the rotative velocity of the pressing roll 4 to the motional velocity of the web W, it is possible e.g. to eliminate even the slightest friction effect between the web W and the pressing roll 4, which could possibly damage the web W. For the implementation of the drive, actuator arrangements known as such are applied, which arrangements will not, however, be discussed in more detail in this context. As for the embodiments of the invention, one alternative can still be presented, in which the pressurized air pocket P is substantially narrower than the reel R, wherein the widest of the pressing rolls 4 in each side gap is substantially narrower than the reel R. When such an embodiment is appropriate, an end seal is produced against the section of the lower surface of the reel R in the most advantageous manner known as such as required by the embodiment, the pressurized air pocket P being in other respects substantially similar to the one described above.

It is obvious that even a larger number of pressurized air pockets P can be placed successively below the reel in the peripheral direction, wherein e.g. the over-pressures prevailing therein are adjusted so that they are most appropriate to the pressurized air pocket in question. Also in this case, as in the embodiment comprising one pressurized air pocket P, it is, of course, possible that the end of the pressing roll P extends outside the end of the reel, wherein the end seal solution most advantageous at a time is applied.

It is also possible to place separate pressurized air pockets P and structures associated therewith along the width direction of the reel. The middlemost air pocket or pockets can be provided with a higher over-pressure than those located by the edge. The ends of the middlemost air pockets can be sealed against the surface of the reel and the outermost ones can be sealed at the ends of the reel.

The solution according to the invention advantageously supports 10 to 30% of the weight of the machine reel.

The structure of the pressurized air pockets can be designed in such a way that the distance of the reels 4 in the direction of the periphery of the reel R has to be changed, wherein the influence area of the pressure and the corresponding force effect can be adjusted.

In order to move the pressurized air pocket P into connection with the reel R and off the same, it is possible to use the same pneumatic, hydraulic or other corresponding actuators which also influence the loading of the pressing rolls 4 against the reel R.

Because it is possible to produce the force effect lifting the reel R by means of actuators loading the pressurized air pocket as well as by means of the over-pressure, it is obvious that the presented method and device are well suited for various operating situations in the reel- up. The operating situations may differ from each other in accordance with the paper grade, the width of the reel, the advancing speed of the web or other corresponding variable. Thus, the significant point is that it is possible to adjust the loading caused by the pressing rolls at the same time when it is possible to maintain the lifting force effect of the pressurized air constant.

The invention is suitable especially for running situations at the stage where the weight of the reel has increased to such an extent that the deflection becomes a problem. The motion of the pressurized air pocket which follows the growth of the radius of the reel R and which can be implemented by means of the aforementioned actuators does not necessarily extend so far that it would follow the growth of the reel R all the way form the beginning, but the length of motion can be adapted in such a way that its uppermost position corresponds to a given minimum diameter of the reel R. The pressurized air pocket P and the structures belonging thereto can be arranged transferable also in the machine direction in the direction of arrow L, wherein it can move along with the reel R when proceeding to a reeling process with the nip open, during which the web W is passed from the reelig cylinder 3 slopingly downwards to the reel R without a pressure contact between these two. The pressurized air pocket can thus also be used to prevent the access of air to the reel in this reeling situation before cutting off the web W and changing it to a new reel spool. The pressurized air can then still be used, but the pressing of the web against the reel can be effected with a mere pressing roll 4. To implement these functions of the change stage, the pressurized air pocket P and the actuators loading/moving the same can be placed so that they move along with the reeling carriage transferring the reel spool 1. The mantle 5 of the pressurized air pocket P can be accomplished with a sufficiently firm box structure to which pressurized air connections can be attached. The pressing rolls 4 can be joumalled on the uppermost edges of the walls of the box so tightly that pressurized air cannot, in practice, escape between the roll and the wall. Furthermore, as for the stiffness of the materials of the box and the pressing rolls, a point to be taken into account is that they have to be able to adapt themselves to the deflections of the reel.

The method and device according to the invention in supporting of the reel are not restricted solely to the embodiments presented above and shown in the drawing, but they can be modified within the scope of the inventive idea of the appended claims. Pressurized air refers e.g. to all gaseous, pressurized media suitable for a reel-up, irrespective of their composition. Similarly, paper web refers to all reelable materials made of fibrous pulp in the form of a continuous web, irrespective of their grammage.

Claims

Claims:

1. Method in supporting of a reel in continuous reeling, in which

- a full-width web (W) is accumulated via a reeling nip (N) to form a machine reel (R) around a reel spool (1) supported at least by its ends,

a force effect lifting the reel (R) is applied to the lower surface of the reel (R) to maintain the reel spool (1) and the reel (R) substantially straight in the direction of their longitudinal axes, wherein

to attain a lifting force, at least one pressurized air pocket (P) is formed against a section of the lower surface of the reel (R),

characterized in that at least one of two side gaps (6) left between the edges of the mantle (5) of the pressurized air pocket (P) parallel to the reel spool (1) and the surface of the reel (R), is sealed with a pressing roll (4) parallel to the reel spool (1), especially to seal off the pressurized air pocket (P).

2. Method according to claim 1 , characterized in that the end gaps (7) left between the ends of the side gaps (6) of the pressurized air pocket

(P) are sealed with end seals (8).

3. Method according to claim 1 or 2, characterized in that the reel (R) is supported and the side gaps are sealed with at least two pressing rolls (4) placed in separate side gaps (6).

4. Method according to any of the foregoing claims, characterized in that the force effect applied to the reel (R) is adjusted by adjusting the loading of the pressing roll/s (4) against the reel (R).

5. Method according to any of the foregoing claims, characterized in that the force effect lifting the reel (R) is adjusted by adjusting the air presure in the pressurized air pocket (P).

6. Method according to any of the foregoing claims, characterized in that the pressing roll/s (4) is/are rotated with a drive.

7. Method according to any of the foregoing claims, characterized in that the pressurized air pocket or pockets and the pressing roll or rolls (4) support 10 to 30% of the weight of the reel (R).

8. Device in supporting of the reel in a continuous reel-up, which device is composed of at least one pressurized air pocket (P) located against a section of the lower surface of the machine reel (R) formed of a full- width web (W) around a reel spool (1) supported at its ends, inside which pressurized air pocket (P) prevails an over-pressure excerting a lifting force effect on the section of the lower surface of the reel (R) with the purpose of maintaining the reel spool (1) and the reel (R) substantially straight in the direction of their longitudinal axes, characterized in that the pressurized air pocket (P) comprises at least one pressing roll (4) placed in the side gaps (6) between its mantle (5) and the lower surface of the reel (R), especially for sealing of the side gap (6).

9. Device according to claim 8, characterized in that there are at least two pressing rolls (4), at least one in each side gap (6).

10. Device according to claim 8 or 9, characterized in that the loading of at least one pressing roll (4) against the reel (R) is arranged adjustable.

11. Device according to claim 8, 9 or 10, characterized in that at least one pressing roll (4) is equipped with a drive to rotate the pressing roll (4).

12. Device according to any of the claims 8 to 11 , characterized in that the end gaps (7) of the mantle (5) are provided with end seals (8).

13. Device according to any of the claims 8 to 12, characterized in that at least one pressing roll (4) is substantially equal in width with the reel (R) or wider than the reel (R).

14. Device according any of the claims 8 to 12, characterized in that at least one pressing roll (4) is substantially narrower than the reel (R).

15. Device according to claim 13, characterized in that the end seals (8) seal off the end gaps (7) of the pressurized air pocket (P) against the ends of the reel (R).

16. Device according to claim 14, characterized in that the end seals (8) seal off the end gaps (7) of the pressurized air pocket (P) against a section of the lower surface of the reel (R).