Method and device for winding a paper or board web

Abstract

The invetion realtes to a method in winding, wherein separate rolls are formed side by side around roll cores (10a, 10b) placed one after the other while supported bz support members and wherin the roll cores (10a, 10B) are pressed at their ends against one another by means of core chucks (20) arranged in connection with the free ends of the outermost roll cores (10a, 10b). In te method, the roll cores (10a, 10b) are placed in a desired position and subjected to a desired compression force by means of the core chucks (20), the lenght of the row of the rool cores (10a, 10b) is determined, and the compression force of at lest one core chuck (20) is regulated during winding when the lenght of the roll core row changes to keep the compression force and/or the lenght of the roll core row within desired limits. The invention also relates to advice in winding wherein separate rolls are formed side around roll cores (10a, 10b) placed one after the other while supported ba support member, which device is a core chuck (20) arranged in connection with the free ends of the outermost roll cores (10a, 10b). At least one core chuck (20) comprises measuring devices (21, 23) for measuring the position and the compression force of the core chuck (20) and control devices (22) for controlling the opeation of the coree chuck (20) to keep the position and the compression force of the core chuck (20) as desired.

Description

[0001] The invention relates to a method according to the preamble of claim 1.

[0002] The invention also relates to a device according to the preamble of claim 5.

[0003] In two-drum winders, in which narrower component webs slit with a slitter-winder from a web unwound from a machine reel are wound into customer rolls, the rolls are usually placed side by side on two winding drums. Because of variations in the cross-direction profiles, for example, thickness, moisture and roughness, of the web to be wound, adjacent rolls are not formed with precisely equally large diameters, in spite of the fact that, in principle, precisely equally long component webs are wound into them. Owing to the different diameters of the rolls, the roll cores placed in the roll centres are displaced with the progress of winding in relation to one another so that their centres of rotation are separated and, at the same time, minor variations also occur in the angular speeds of the rolls. Since the roll centres are, however, in contact with each other during the entire winding process, diverting forces arise between the ends of the roll cores, and the rolls tend to “jump”, in which connection the rolls that are being formed can be damaged. Owing to this detrimental vibration, in two-drum winding, it is generally necessary to run at a lower speed, i.e. to be content with a lower winding speed, which reduces the capacity of the machine and is, thus, uneconomical.

[0004] The problem described above has occurred as long as winders of the two-drum type have been in use. The seriousness of the problem has, however, varied in the course of years, because the profile of the web produced on a paper machine has improved and, at the same time, the roll size and the winding speed have changed to a little extent only. In recent years, the diameters of the customer rolls produced have started becoming ever larger and, at the same time, the winding speeds have also increased, for which reason the problem of vibration has been noticed again: even a little variation of profile in the direction of width of the web is cumulated especially during winding of thin paper grades so that faults in the shape of the rolls which arise from the web profile cause a significant vibration problem.

[0005] In the winding process, a number of different phenomena are effective which attempt to shift the web rolls that are being formed in their axial direction:

[0006] deflection of winding cylinders, i.e. winding drums,

[0007] faults in the shape of the rolls arising from uneven profile of the web, and

[0008] also the core chucks, which support the roll cores of the outermost web rolls, subject the row of rolls to axial forces when they keep the row of rolls in the desired position.

[0009] The core chucks alone can also produce a compression force applied to the whole row of roll cores when the roll cores are excessively long: the total length of the roll cores is higher than the regulated distance between the core chucks.

[0010] One problem in winding is also that the length of the roll cores, for example, roll spools, changes during winding because with some core and paper qualities the compression pressure caused by the web being wound onto the core gives rise to elongation of cores.

[0011] When roll cores are pressed in their position at their ends by means of core chucks, a problem is also that there is often either too much or too little pressing. In a situation where the core chucks press too much, the vibration problems described above arise and if the chucks are again too loose, there are lateral shifts. Because of the problems of the type described above, determining of the correct pressing force and position of the core chucks is very problematic.

[0012] The phenomena described above can, either alone or together, produce situations in which the rolls or the ends of the roll cores tend to be pressed against each other and thereby to produce a relative support force, thus causing vibration problems.

[0013] Thus, there are several factors that produce a relative axial thrust force between the rolls. The core chucks, which keep the outermost roll cores in their positions, keep the row of rolls in the correct winding position in the lateral direction, but deflection of the winding drums drives the rolls towards the lowest point of deflection. Variations in the web profile produce a “carrot shape” even in individual rolls, in which case the rolls tend to move in the lateral direction. Of course, variations in the lengths of the roll cores, together with the core chucks, cause variation in the axial forces in different forms. It comes out from the above that there are a number of different reasons why the rolls tend to be pressed against each other during winding, thus generating vibration that limits running speeds and even damages the rolls.

[0014] The problems described above occur in all such winder types in which the location/support of the web rolls that are formed comply with the following terms:

[0015] the roll cores (web rolls) are placed one after the other coaxially so that the location of each roll core is determined by means of the adjacent roll cores,

[0016] the roll cores (web rolls) are supported under optimal conditions in the radial direction of the rolls only (the core chucks just prevent axial movement arising from faults in the roll shapes and from deflection of the winding members).

[0017] It is an object of the invention to provide a method and a device which, when used, eliminate or at least minimize the problems described above.

[0018] A particular object of the invention is to provide a method and a device in which the compression force and/or position of the core chuck can be adjusted in an optimal manner.

[0019] With a view to achieving the objects described above as well as those which are coming out later, the method according to the invention is mainly characterized in that which is stated in the characterizing part of claim 1.

[0020] The device according to the invention is in turn mainly characterized in that which is stated in the characterizing part of claim 5.

[0021] In accordance with the invention, measuring devices for measuring the position and force of the chuck as well as machine controls for controlling the operation of the core chuck are arranged in connection with the core chuck such that the position and/or the force of the chucks is/are in a desired value range, i.e. within desired limits, and no detrimental vibration is generated because of axial forces of detrimental magnitude between the roll cores. In accordance with an advantageous embodiment of the invention, core chucks according to the invention are placed at both ends of a row of roll cores. However, in accordance with the invention it is also possible to place such an inventive core chuck with its measuring devices and control arrangements only at one end of a row of core chucks.

[0022] In accordance with the invention, after feeding the roll cores, for examples, roll spools, the roll cores are placed by means of core chucks in positions in compliance with the trim, i.e. desired component web widths, and the length of the row of roll cores is measured by means of position and compression pressure sensors placed in the core chucks. During winding, when the length of the roll cores changes, the axial compression force of both chucks is most advantageously kept within desired limits, for example, at a set value by adjusting the position of both chucks in a centralized manner.

[0023] The trim data in accordance with the invention, i.e. information about the width of the web rolls to be wound, is obtained from the control system of the machine and the length of the roll core set, by which are meant the roll cores which are placed side by side in a row in an abutting relationship with respect to each other and which are situated between the core chucks, is measured when the core chucks have been placed in the desired pressing position. When needed, the position of the core chuck/chucks is adjusted in a centralized manner.

[0024] In the position measurement in accordance with the invention, a position sensor is advantageously used as the measuring device and in the force measurement in accordance with the invention, a pressure or force sensor is advantageously used as the measuring device.

[0025] The necessary machine controls of the core chucks are advantageously accomplished by means of electric, hydraulic and/or pneumatic actuators.

[0026] In the following, the invention will be described in more detail with reference to the FIGURE of the appended drawing, to the details of which the invention is, however, not by any means meant to be narrowly confined, which FIGURE schematically shows core chucks in accordance with one advantageous application of the invention.

[0027] The FIGURE has been cut such that in the middle of the FIGURE in the invisible portion there are the cores other than the portions of the outermost cores 10a, 10b of a row visible in the FIGURE, onto which cores the component webs produced in slitting are wound.

[0028] As shown in the FIGURE, a core chuck 20 is placed at either end of the core set 10a, 10b, said core chuck comprising measuring devices 21 for measuring the position of the core chuck 20 and measuring devices 23 for measuring compression force. In addition, the system comprises control devices 22 for adjusting the position of the core chucks 20 as desired based on the result of measurement. In other respects, the core chuck 20 is accomplished in a manner known in itself from the prior art such that it comprises a conical part placed inside the core 10a, 10b, a fixing part 31 which can be moved in the direction of the row of cores 10a, 10b to produce a desired compression force by means of an actuator, for example, a hydraulic, electric or pneumatic actuator, which is arranged to be movable in a shaft 33 placed inside frame parts 34 of the core chuck 20.

[0029] The measuring device 21 for measuring the position of the core chuck 20 is advantageously an absolute position sensor. A pressure or force sensor is advantageously used as the measuring device 23 for measuring the compression force of the core chuck 20. The control devices 22 used for controlling the operation of the core chuck 20 are electric, hydraulic and/or pneumatic actuators. Advantageously, the measuring devices 21, 23 and the control devices 22 of both core chucks are arranged to cooperate such that the position of the core chucks 20 can be adjusted in a centralized manner.

[0030] In accordance with the invention, the operation of the core chuck 20 is controlled such that the position of the core chucks is as desired and their axial compression force is within desired/set values. The desired compression force is produced, for example, by the moment of a motor, by hydraulic or pneumatic cylinders provided with feedback to the force or pressure sensor. When needed, desired limit values can also be set for the position of the core chucks, in which connection the regulation of the axial compression force takes place based on distance limits.

[0031] Above, the invention has been described with reference to one of its advantageous embodiment examples only, to the details of which the invention is not by any means intended to be narrowly confined.

Claims

1. A method in winding, wherein separate rolls are formed side by side around roll cores (10a, 10b) placed one after the other while supported by support members and wherein the roll cores (10a, 10b) are pressed at their ends against one another by means of core chucks (20) arranged in connection with the free ends of the outermost roll cores (10a, 10b), characterized in that, in the method, the roll cores (10a, 10b) are placed in a desired position and subjected to a desired compression force by means of the core chucks (20), the length of the row of the roll cores (10a, 10b) is determined, and the compression force of at least one core chuck (20) is regulated during winding when the length of the roll core row changes to keep the compression force and/or the length of the roll core row within desired limits.

2. A method according to claim 1, characterized in that, in the method, the position of both core chucks (20) is adjusted.

3. A method according to claim 1 or 2, characterized in that, in the method, the position of the core chuck/chucks (20) is adjusted in a centralized manner.

4. A method according to claim 1, characterized in that, in the method, the position of a core chuck/the core chucks (20) is measured to measure the length of the roll core row.

5. A device in winding wherein separate rolls are formed side by side around roll cores (10a, 10b) placed one after the other while supported by support members, which device is a core chuck (20) arranged in connection with the free ends of the outermost roll cores (10a, 10b), characterized in that at least one core chuck (20) comprises measuring devices (21, 23) for measuring the position and the compression force of the core chuck (20) and control devices (22) for controlling the operation of the core chuck (20) to keep the position and the compression force of the core chuck (20) as desired.

6. A device according to claim 5, characterized in that the measuring devices (21, 23) and the control devices (22) are arranged in connection with both core chucks (20).

7. A device according to claim 5 or 6, characterized in that the measuring device (21) for measuring the position of the core chuck (20) is a position sensor.

8. A device according to any one of claims 5 to 7, characterized in that the measuring device (23) for measuring the compression force of the core chuck (20) is a moment, pressure or force sensor.

9. A device according to any one of claims 5 to 8, characterized in that the control devices (22) for controlling the operation of the core chuck (20) comprise hydraulic, electric and/or pneumatic actuators.

10. A device according to claim 6, characterized in that the measuring devices (21, 23) and the control devices (24) of both core chucks (20) are arranged to cooperate such that the position of the core chucks (20) can be adjusted in a centralized manner.