WO2010022772A1

WO2010022772A1 - Device and method of determining an air trapping profile of a fiber web roll in a paper or cardboard machine and use of the device in a reel-up

Info

Publication number: WO2010022772A1
Application number: PCT/EP2008/061231
Authority: WO
Inventors: Tatu PITKÄNEN; Jari Tiitta; Matti M. Kemppainen; Petteri Lannes
Original assignee: Metso Paper Oy
Current assignee: Valmet Technologies Oy
Priority date: 2008-08-27
Filing date: 2008-08-27
Publication date: 2010-03-04
Anticipated expiration: 2011-02-27

Abstract

A device is provided, which determines an air trapping profile of a fiber web roll (10) in a paper or cardboard machine. The device comprises a supporting means (20), a first sensing means (40) supported by the supporting means (20) and measuring a first diameter profile of the fiber web roll (10) at at least one first axial position along a cross machine direction (CD), a load applying means (50) supported by the supporting means (20) and applying a radial load on the surface of the roll (10) at at least one second axial position along the cross machine direction (CD), a second sensing means (42) supported by the supporting means (20) and measuring a second diameter profile of the roll (10) at said second axial position, and a processing means which determines an air trapping profile of the roll (10) based on a difference between the first and second diameter profiles. Further, use of the measured results as well as the method for obtaining the results is described.

Description

Device and method of determining an air trapping profile of a fiber web roll in a paper or cardboard machine and use of the device in a reel-up

Description

The present invention relates to a device according to claim 1 and a method according to claim 13, which device and method determine an air trapping profile of a fiber web roll in a paper or cardboard machine, and to a use of the device in a reel-up according to claim 12.

Background of the invention

According to the prior art as shown, for example, in US 2008/0017341 Al, there is known a method and a system to control a reeling profile of a fiber web reel, when a fiber web is reeled around a reeling core. A measuring device for a hardness profile of the fiber web reel includes a so- called "back tender's friend" means, which has a measuring wheel, which is loaded against the surface of the reel to measure the hardness profile of the reel.

There is no method, system or apparatus known for measuring the amount of air remaining below the outer layers of a web or the profile of the amount of air when, for example, a web is reeled up onto a reeling core.

It is therefore an object of the present invention to provide a device and a method of determining an air trapping profile of a fiber web roll in a paper or cardboard machine along a cross machine direction, which device and method are able to suitably measure the amount of air inside the fiber web roll. The object of the present invention is achieved by the device according to claim 1 and the method according to claim 13.

It is an advantage of the present invention to use the device in a reel-up as it is defined in claim 12.

Further advantageous developments are defined in the dependent claims.

According to an aspect of the present invention, there is provided a device determining an air trapping profile of a fiber web roll in a paper or cardboard machine. The device comprises a supporting means, a first sensing means supported by the supporting means and measuring a first diameter profile of the fiber web roll at at least one first axial position along a cross machine direction, a load applying means supported by the supporting means and applying a radial load on the surface of the roll at at least one second axial position along the cross machine direction, a second sensing means supported by the supporting means and measuring a second diameter profile of the roll at the at least one second axial position, and a processing means which determines an air trapping profile of the roll based on a difference between the first and the second diameter profiles.

Preferably, the first sensing means is adapted to measure the first diameter profile at several first axial positions (at a plurality of first axial positions) along the cross machine direction, the load applying means is adapted to apply the radial load at several second axial positions (at a plurality of second axial positions) along the cross machine direction, the second sensing means is adapted to measure the second diameter profile at the plurality of second axial positions, and the processing means is adapted to determine the air trapping profile along the along cross machine direction based on a difference between the first and second diameter profiles.

According to the above aspect, the load applying means locally pushes aside the air between the layers of the roll at the at least one axial position and the sensing means measure the respective diameter profiles so that the processing means can determine the air trapping profile of the roll based on (concluded from) the difference of the mentioned profiles, wherein a such air trapping profile may represent an air amount distribution profile in the circumference direction of the roll. In other words, it is possible to conclude an average amount of remaining air within the roll at the at least one axial position and to suitably determine the amount of air inside the roll at this position.

Further, according to the above aspect of the present invention, the web roll is scanned by the load applying means. This load applying means preferably comprises at least one spring-loaded back tender' s friend wheel (BTF wheel) which is arranged to press on the surface of the roll by means of a spring, air cylinder, hydraulic cylinder and/or the dead weight of the wheel itself along the cross machine direction. Thus, the load applying means locally removes (pushes aside) the air between the layers of the roll, especially the upper surface layers of the roll, at the at least one point or the plurality of second axial positions at which the load applying means presses on the surface of the roll. The device according to the above aspect further includes the first sensing means supported by the supporting means. Preferably, the first sensing means measures the first diameter profile of the roll at points (i.e. the plurality of first axial positions) which are not pressed by the load applying means. In other words, the first sensing means determines the first diameter profiles at such points which are not loaded by the load applying means. Thus, the respective measured first diameter profiles include the amount of air included within the web layers of the roll.

The second sensing means is supported by the supporting means and may measure the second diameter profile of the roll at points (i.e. the plurality of second axial positions) at which the air is pressed out (i.e. locally removed or pushed aside) between the web layers of the roll. In other words, the second sensing means determines the second diameter profiles at such points which are loaded by the load applying means. These second diameter profiles are profiles measured without air within the layers of the roll.

Preferably, the measured diameter profiles are mapped to encounter with each other at substantially the same axial positions (i.e. corresponding axial positions) along the cross direction. From the first diameter profile measured without the BTF wheel pressing on the surface of the roll is subtracted the second diameter profile measured under the load application of the wheel, whereby the remainder (i.e. the difference between the first and second diameter profiles at the corresponding axial positions) stands for the profile of an amount of air or an air film remaining in the layers of the roll. Thus, this air trapping profile of the roll is determined along the cross machine direction. Using the determined values, it is possible to conclude an average amount of remaining air within the roll along the entire cross machine direction and to suitably determine the amount of air inside the roll, for example, the whole roll.

Preferably, the load applying means is pivotably supported by a supporting arm of the supporting means. The load applying means may consist of a plurality of spring-loaded BTF wheels successively arranged along the cross machine direction and each of them individually pressing on the surface of the roll by means of, for example, a spring and/or the dead weight of each wheel when supported above the roll.

Alternatively, a travelling means supporting the first sensing means, the load applying means and the second sensing means is guided on the supporting means so as to be movable along the cross machine direction. In this case, the load applying means may comprise a single spring-loaded BTF wheel pressing on the surface of the roll by means of a spring and/or the dead weight of the wheel, while the travelling means moves along the cross machine direction. Thus, the number of components and the controlling efforts can be reduced.

It is further possible that the single BTF wheel or each of the BTF wheels may be loaded by a power cylinder using compressed air as an air spring or hydraulic fluid as a hydraulic fluid spring for individually pressing each of the wheels against the surface of the roll.

Further preferably, both sensing means are distance measuring means using laser light. Alternatively, it is sufficient that one of the two sensing means is a laser distance measuring means and the other one is provided as an angle sensor arranged at the supporting arm of the BTF wheel. This angle sensor may use laser light. The sensor can determine the second diameter profile of the roll along the cross machine direction based on a comparison between detected angles and a reference angle. Preferably, the angle sensor measures a relative angle between the supporting arm and the supporting means at each second axial position. Thus, it is preferable that the processing means determines the second diameter profile of the roll at the second axial positions based on a difference between the measured relative angles and reference relative angles.

Preferably, the reference (relative) angle (s) can be estimated from the distance measurement results gathered by the laser distance measuring means (first sensing means) and thus corresponds to angle positions of the supporting arm in which the loading means does not apply a load on the surface of the roll.

In case the two sensing means are distance measuring means using laser light, the distance measuring means may emit laser light to the surface of the roll at the first and second axial positions and receive laser light reflected at said positions, respectively.

From the above, it is shown that it is possible to extend the use of the second sensing means (preferably used in common with the BTF wheel in connection with the load applying means) to measure the hardness profile and the diameter profile of the wheel below the BTF wheel and to determine the amount of air within the roll by means of the first and second sensing means. Further preferably, the supporting means is part of a frame structure of the paper or cardboard machine and comprising a crossbar which is, for example, arranged above the roll. Additionally, a guiding rail may be integrally formed at the frame so as to support the travelling means.

Further, it is not required that the crossbar is positioned above the roll. The crossbar can be arranged at an arbitrary position around the outer circumference surface of the roll in predetermined radial distance with respect to the roll.

According to a further aspect of the present invention, it is preferable to use the device in a reel-up such that winding parameters for forming a fiber web roll in the reel-up are adjusted based on or considering the air trapping profile determination of the device in order to obtain an even air trapping profile of the roll along the cross machine direction. According to this preferred constitution, the measuring results can be used in adjusting the winding parameter for optimizing the reel-up adjustment parameters. This can be done by increasing the nip load, peripheral forces etc., when the amount of air increases or decreases in different zones at the roll along the cross machine direction.

In case a reel-up drum is used at the reel-up, in which drum loads are adjustable along different zones in the cross machine direction, those zones in which the amount of air is increased can be loaded with a larger load in order to obtain a substantially even air trapping profile of the fiber web roll along the entire cross machine direction. According to another aspect of the present invention, a method of determining an air trapping profile of a fiber web roll in a paper or cardboard machine is provided. The method comprises the steps of winding the fiber web to form a fiber web roll in a reel-up, measuring a first diameter profile of the roll at at least one first axial position thereof, applying a radial load on the surface of the roll at at least one second axial position thereof, measuring a second diameter profile of the roll at the at least one second axial position, and determining an air trapping profile of the roll based on a difference between the first and the second diameter profiles.

Therefore, according to the above method, the same advantages and effects are obtained as mentioned in connection with the constitution of the device according to the aspect of the present invention. According to the above method, it is, for example, possible to obtain an average amount of remaining air within the roll along the entire cross machine direction and to suitably determine the amount of air inside the roll.

Preferably, the step of measuring the first diameter profile is performed previous to the step of measuring the second diameter profile. The step of measuring the second diameter profile and the step of applying the radial load can be performed simultaneously in order to reduce computing time for determining the air trapping profile of the roll so that controlling parameters for changing the diameter profiles along the cross machine direction can be rapidly set.

Alternatively, the step of measuring the first diameter profile, the step of measuring the second diameter profile and the step of applying the radial load can be performed simultaneously. Thus, the computing time can be further reduced and controlling parameters for changing the diameter profiles along the cross machine direction can be obtained at an early stage.

Preferably, according to the measurement results gathered by the above method according to the invention and representing a profile of an amount of air or an air film remaining in the layers of the roll (i.e. the air trapping profile) , it is possible to draw conclusions about the air permeability for a paper or cardboard or the like used in a reel-up. Thus, an evaluation of the paper or cardboard quality can be made based on such conclusions.

Further, it is preferably possible to estimate the air amount per web layer wrapped around the roll when reeling up the web on the basis of the measured and determined air trapping profile.

The present invention can be better understood, when the following detailed description of the preferred embodiments is considered in connection with the appended drawings.

Brief description of the drawings

Fig. 1 is a top view schematically showing a device of determining an air trapping profile of a fiber web roll in a paper or cardboard machine along a cross machine direction according to a first embodiment of the present invention;

Fig. 2 is a sectional view along line II-II in Fig. 1, schematically illustrating a modification of the first embodiment of the present invention; and Fig. 3 is a sectional view corresponding to line II-II in Fig. 1 and schematically showing a device of determining an air trapping profile of a fiber web roll in a paper or cardboard machine along a cross machine direction according to a second embodiment of the present invention.

In the embodiment as shown in Fig. 1, a fiber web roll 10 is shown from above. The roll 10 is constituted of a paper or cardboard web reeled up in a reel-up in a paper or cardboard machine (not shown) .

A frame 20 acting as a supporting means comprises a crossbar 22 and supporting plates 26 arranged on the left and right end sides of the crossbar 22 to position and mount the crossbar 22 at a predetermined height above the roll 10 in a common frame structure of the paper or cardboard machine (not shown) . The supporting plates 26 and the crossbar 22 are integrally formed with each other. The supporting plates 26 are joined to the respective end of the crossbar by welding, bonding or the like. The supporting plates 26 are attached to the common frame structure by means of screws or the like. The constitution of the attachment of the supporting bars 26 within the paper or cardboard machine is commonly known and the further description thereof is omitted. Thus, the crossbar 22 is stably arranged above the roll 10 and extends along a cross machine direction CD.

On the upper side of the crossbar 22, there is provided a guiding rail 24 which is integrally formed on the crossbar 22. The guiding rail 24 extends via the whole crossbar 22 along the cross machine direction CD.

A carriage 30 as a travelling means is supported, preferably slidably supported, by the guiding rail 24. The carriage 30 is thus reciprocally arranged on the crossbar 22 in the cross machine direction CD. The movement of the carriage 30 along the cross machine direction CD is established by a motor (not shown) . The motor for moving the carriage 30 can be an electric motor or the like.

The carriage 30 comprises a first sensor 40 as a first sensing means, a second sensor 42 as a second sensing means, a load applying means 50 consisting of a supporting arm 54 and a back tender's friend wheel 52 (a so-called BTF wheel 52) and a spring 56.

The supporting arm 54 extends vertically with respect to the cross machine direction CD towards to the surface of the roll 10. At one end of the supporting arm 54 (lower end in Fig. 1), the BTF wheel 52 is rotatably supported by an axis of the supporting arm 54. On the other end of the supporting arm 54 (upper end) there is provided the spring 56 housed within a spring cover in order to apply a predetermined load via the supporting arm 54 and the BTF wheel 52 to the surface of roll 10. In other words, the spring-loaded BTF wheel 52 presses against the surface layer of the roll 10 by a predetermined load, which is described below in detail.

The first sensor 40 is integrally or detachably mounted to the carriage 30 and emits laser light to the surface of the roll 10 at a plurality of first axial positions of the roll 10, when the carriage 30 is moved along the cross machine direction CD, and receives the laser light reflected at this first axial positions.

Thus, the first sensor 40 corresponds to a distance measuring means using laser light. When measuring the distance at the several first positions by moving the carriage 30 along the cross machine direction CD, a first diameter profile of the roll at said first axial positions along the cross machine direction can be determined. The first diameter profiles correspond to diameter profiles measured with the amount of air included between the web layers of the roll 10.

The second sensor 42, which is integrally or detachably mounted to the carriage 30, is a distance measuring means using laser light. According to the first embodiment, the second sensor 42 emits laser light to an arm portion 58 of the supporting arm 54, which portion extends vertically with respect to the extension direction of the supporting arm 54 (i.e. parallel to the cross machine direction CD), and receives the laser light reflected at the arm portion 58 of the supporting arm 54. The arm portion 58 of the supporting arm 54 is integrally formed with the supporting arm 54. Since the supporting arm 54 is spring-loaded by the spring 56, when the arm 54 and thus the BTF wheel 52 are pressed down (i.e. the predetermined load is applied to the surface roll 10), the distance between the arm portion 58 and the second sensor 42 changes (elongates) compared to the case in which the BTF wheel 52 is not spring-loaded and is thus slidably in contact with the surface of the roll 10 without applying the predetermined spring load.

Therefore, the second sensor 42 measures a second diameter profile of the roll 10 at a plurality of second axial positions when the carriage 30 is shifted along the cross machine direction CD.

By the distance measurement of the second sensor 42, the second diameter profiles of the roll are determined at said several second axial positions. Thus, the second diameter profile measurement represents a measurement of a roll diameter when the air inside the roll 10 is pushed out by the spring-loaded BTF wheel 52.

Thus, while the carriage 30 reciprocates along the cross machine direction CD, for example, during reeling up the web, the first and the second diameter profiles of the roll 10 are determined at several first and second axial positions of the roll 10.

A processing means, for example a computer or the like, which is not shown in Fig. 1, determines an air trapping profile of the roll 10 based on a difference between the first and second diameter profiles. Based on this determined air trapping profile of the roll 10, for example, in a reel-up (not shown) of the paper or cardboard machine, an even air trapping profile of the roll 10 along the cross machine direction can be obtained by adjusting the reel-up winding parameters to form the fiber web layers wrapped around as the fiber web roll 10 based on or considering the air trapping profile determination of the processing means.

According to Fig. 2, a modification of the first embodiment in Fig. 1 is schematically shown, wherein parts of the guiding rail 24 and of the loading means 50 are not explicitly illustrated for simplifying of the illustration of the device in Fig. 2.

In comparison to the constitution of the embodiment as shown in Fig. 1, the arm portion 58 of the supporting arm 54 is not provided. In this modification of the first embodiment, the second sensor 42 is provided at a side protrusion of the carriage 30. The second sensor 42 directly emits laser light to the surface of the roll 10 at the plurality of second axial positions, at which the predetermined load of the spring 56 via the supporting arm 54 and the BTF wheel 52 are applied to the surface of the roll 10, and receive laser light reflected at the second axial positions, while the carriage 30 moves along the cross machine direction CD.

Thus, along the cross machine direction CD, a distance between the sensor 42 and the roll surface is determined at each second axial position in order to obtain the second diameter profiles corresponding to diameter profiles measured without the amount of air included between the web layers of the roll 10.

The remaining parts and measurements as described for the embodiment of Fig. 1 are the same as for the embodiment shown in Fig. 2. Thus, the respective description thereof is omitted.

In Fig. 3, a device of determining an air trapping profile according to a second embodiment of the present invention is shown.

According to the second embodiment, an angle sensor 42 acting as the second sensing means measures a relative angle α between the supporting arm 54 and a bottom surface of the carriage 30, which is guided by the guiding rail 24 along the cross machine direction CD, in each second axial position while the carriage 30 moves along the cross machine direction CD.

Here, the supporting arm 54 pivotably supports the loading applying means 50, in particular, the spring-loaded BTF wheel 52. The spring 56 is arranged between the carriage 30 and the supporting arm 54 in order to apply a predetermined load via the supporting arm 54 and the BTF wheel 52 to the surface of roll 10.

The processing means determines the second diameter profile of the roll 10 based on a difference between the measured relative angle α and a reference relative angle at each second axial position.

The reference angle is determined from the distance measurement results gathered by the first sensing means 40 (not shown in Fig. 3) and corresponds to an angle position of the supporting arm 54 between the bottom surface of the carriage 30 and the supporting arm 54, in which angle position the BTF wheel 52 does not apply the predetermined load on the surface of the roll 10 (i.e. the spring 56 does not apply a load to the supporting arm 54) .

According to the second embodiment, the second sensing means 42 does not measure a distance between the sensing means 42 and the surface of the roll 10 or the arm portion of the supporting arm 54 as shown in Fig. 1 and 2, respectively, the second diameter profile of the roll 10 along the cross machine direction CD is obtained based on the difference between the measured relative angle α and the reference relative angle at each second axial position.

According to the above embodiments, the first and second sensing means use laser light for determining distances and/or relative angles between several components of the device according to the present invention. It is also possible that strain gauges, optical sensors, etc. can be used as the sensing means.

The preceding description of the present invention is merely exemplary, and is not intended to limit its scope in any way. Various details of the present invention may vary within the scope of the invention as defined in the appended claims and may differ from the exemplary details described above in accordance with the knowledge of a person skilled in the art.

Claims

1. A device determining an air trapping profile of a fiber web roll (10) in a paper- or cardboard machine, the device comprising: a supporting means (20), a first sensing means (40) supported by the supporting means (20) and measuring a first diameter profile of the fiber web roll (10) at at least one first axial position along a cross machine direction (CD) , a load applying means (50) supported by the supporting means (20) and applying a radial load on the surface of the roll (10) at at least one second axial position along the cross machine direction (CD) , a second sensing means (42) supported by the supporting means (20) and measuring a second diameter profile of the roll (10) at the at least one second axial position, and a processing means which determines an air trapping profile of the roll (10) based on a difference between the first and second diameter profiles.

2. A device according to claim 1, wherein the first sensing means (40) is adapted to measure the first diameter profile at several first axial positions along the cross machine direction (CD) , the load applying means (50) is adapted to apply the radial load at several second axial positions along the cross machine direction (CD) , the second sensing means (42) is adapted to measure the second diameter profile at the second axial positions, and the processing means is adapted to determine the air trapping profile based along the cross machine direction (CD) on a difference between the first and second diameter profiles .

3. A device according to claim 1 or 2, wherein the load applying means (50) is pivotably supported by a supporting arm (54) of the supporting means (20) .

4. A device according to claims 1 to 3, wherein the load applying means (50) consists of a plurality of spring- loaded BTF wheels (52) each of them individually pressing on the surface of the roll (10) by means of a spring (56) and/or the dead weight of each wheel when supported above the roll (10) .

5. A device according to claims 1 to 3, wherein a travelling means (30) supporting the first sensing means (40), the load applying means (50) and the second sensing means (42) is slidably guided on the supporting means (20) so as to be moveable along the cross machine direction (CD) .

6. A device according to claim 5, wherein the load applying means (50) comprises a spring-loaded BTF wheel (52) pressing on the surface of the roll (10) by means of a spring (56) and/or the dead weight of the wheel (10), while the travelling means (30) moves along the cross machine direction (CD) .

7. A device according to claims 1 to 6, wherein both sensing means are (40, 42) distance measurement means (40, 42) using laser light.

8. A device according to claim 7, wherein the distance measurement means (40,42) emit laser light to the surface of the roll (10) at the first and second axial positions, respectively, and receive laser light reflected at said positions, respectively.

9. A device according to claims 3 to 6, wherein the second sensing means (42) measures a relative angle (α) between the supporting arm (54) and the supporting means (20) at each second axial position, and the processing means determines the second diameter profile of the roll (10) at the second axial positions based on a difference between the measured relative angles (α) and a reference relative angle.

10. A device according to any of the preceding claims, wherein the supporting means (20) is a frame (20) comprising a crossbar (22) which extends along the cross machine direction (CD) .

11. A device according to claims 5 to 9, wherein the supporting means (20) is a frame (20) comprising a crossbar (22) which is arranged above the roll (10) and extends along the cross machine direction (CD), at which frame (20) a guiding rail (24) is integrally formed so as to slidably support the travelling means (30) .

12. Use of the device defined in any of the preceding claims in a reel up such that winding parameters for forming a fiber web roll (10) in the reel-up are adjusted based on the air trapping profile determination of the device in order to obtain an even air trapping profile of the roll (10) along the cross machine direction (CD) .

13. A method of determining an air trapping profile of a fiber web roll (10) in a paper- or cardboard machine, the method comprising the steps of: winding the fiber web to form a fiber web roll (10) in a reel-up, measuring a first diameter profile of the roll (10) at at least one first axial position thereof, applying a radial load on the surface of the roll (10) at at least one second axial position thereof, measuring a second diameter profile of the roll (10) at the at least one second axial position, and determining an air trapping profile of the roll (10) based on a difference between the first and second diameter profiles.

14. A method according to claim 13, wherein the step of measuring the first diameter profile is performed previous to the step of measuring the second diameter profile, and/or the step of measuring the second diameter profile and the step of applying the radial load are performed simultaneously.

15. A method according to claim 13, wherein the step of measuring the first diameter profile, the step of measuring the second diameter profile and the step of applying the radial load are performed simultaneously.