EP0898013B1 - Apparatus and process for controlling or regulating a web property profile - Google Patents

Description

The invention relates to a device for control or regulation of a rail property profile Paper or cardboard web in the manufacturing process of a Paper or board machine according to the preamble of Claim 1. The invention further relates to a Process for controlling or regulating a Web property profile of a paper or board web in the manufacturing process of a paper or Cardboard machine according to the preamble of the claim 23rd

When making a paper or cardboard web there There are numerous disruptive factors in the manufacturing process the web properties of the paper or board web, both in terms of their uniformity over the Machine width, as well as in terms of their Consistency during the manufacturing process, negative can influence. These disruptive factors include for example temperature fluctuations, Pressure fluctuations and manufacturing tolerances or also Errors in the execution or setting of the Paper machine in the manufacturing process. The essential web properties that the quality of the affect the paper that is produced Basis weight, fiber orientation and Formation. However, properties such as the ash content, the opacity, the moisture, the Path thickness and the roughness of the path are essential Role in the quality criteria of a paper web. In usually tries the above Web properties across the entire width of the web and as evenly as possible over the entire length of the web and keep it constant.

To influence a web property profile Paper or cardboard web is the following status Technology known:

From the patent DE 35 35 849 it is known that Width of the outlet gap of a headbox to change certain points of the web width so that the throughput of the stock suspension accordingly changed locally. If the throughput of the Stock suspension with the same across the machine width Concentration changes locally, this causes one Influencing the amount of solids on this Place of the web. Thus, a measure can Setting of the basis weight cross-section reached become.

In another patent application DE 40 19 593 A1 the Applicant, the preamble of claim 1 forms an apparatus and a method for Regulation of the basis weight profile of the web is disclosed. In this case, if the Basis weight profile of the paper web at a certain Place the web width the concentration of the Material suspension flow changed at this point become. To achieve this, it is proposed that Headbox at least partially over the Section width and with the help of regulated section flows with individual adjustable concentration. The individual adjustment of the concentration of the the respective section flow takes place through a regulation the inflow conditions of two individual flows with constant but different concentration. Due to the different content of the Section flows of fiber, ash and other Aggregates there is a change in Basis weight at the corresponding point of the Web width.

The basis weight cross-section is used in the control procedure the paper web measured at the end of the paper machine and with a control loop the inflow conditions of the two single streams of different concentration, which form the respective section flow regulated in such a way that a surface weight cross section as uniform as possible arises.

A similar control device, as well as a Process for controlling the basis weight cross-section and the fiber orientation cross profile is from the Patent application DE 42 39 845 of the applicant is known. This registration provides for the headbox as well train at least partially sectionally and Pulp suspension in the individual sections a supply of dilution water or other Fluids in its consistency and / or To influence fiber orientation so as to to regulate the corresponding cross profile. A similar one sectional headbox is from the patent DE 43 16 054 known.

Furthermore, reference is made to the patent specification DE 196 34 997 pointed out that a control device with a A plurality of measuring sensors and a method for Regulation of various rail property profiles describes. The patent specification DE 196 34 996 pointed out that a sectionally density-controlled headbox with a Pulp consistency control disclosed.

In patent applications DE 42 11 291 and DE 42 11 290 is a sectional fabric density control of a Headbox with a single valve per section shown with constant volume flow. In the Patent applications DE 40 19 593 and DE 41 12 347 a material density control and volume flow control for a sectioned headbox with two valves each shown.

A major problem of the above rule and Control devices and methods of the above State of the art is that under unfavorable conditions individual actuators, such as for example valves for regulating the Concentration or consistency, or also Adjustments on the headbox cover, in an end position. Will in one Such a situation is a more extensive one, about the End position of the actuator beyond Control command given to the corresponding actuator, this cannot be done. Thereby there is no desired change in the web property at the appropriate point on the profile, though that Process control system the need for a has recognized the corresponding change and it arises self-locking of the control system.

Such an end position of an actuator can consist, for example, that a valve one Dilution water supply line of a mixer either in maximum open or maximum closed position is and therefore no further change in the substance concentration the corresponding section is possible. It can However, it may also be that on an aperture of the Headbox for example the maximum opening of the Aperture is set and another opening is requested and there is no possibility for this. These situations cause the Web properties cross profile through the control device cannot be improved and thus with significant loss of quality in the manufacturing process is to be expected.

It is an object of the invention, the known Control device according to the preamble of the claim 1 to improve in that the above Self-blocking of the scheme is avoided. Furthermore, a corresponding method for Control or regulation of a web property profile be proposed.

The object of the invention is characterized by the features of first device claim and the first Process claim resolved.

According to the characterizing features of the first device claim suggested that at least one adjustable means for web widths Influencing the cross-sectional properties of the web Railway property is provided and that a means for Inclusion of information about the position of a or several of the multitude of actuators for the sectional Influencing the cross-sectional properties of the web Railway property for regulating or controlling an or several of the means for influencing the web width Railway property cross profile of the railway property is provided.

According to the distinctive features of the first Process claim is proposed that the position one or more of the plurality of actuators for sectional influencing of the web property cross profile the web property in a computer unit with the Calculation of a correction value of at least one adjustable means for influencing the web width Railway property cross profile of the railway property processed and included and that the Railway property cross profile of the railway property through Adjustment of one or more of the means for web width influencing the web property cross profile the web property based on the calculated Correction value is corrected.

The basic idea of the invention is therefore in a control process or in a control device previously known situation of adjusting individual, actuators only acting on a specific section by adjusting one to the entire web width acting actuator for a particular Layer property to overlay, so that the Sectional acting actuators if possible not in one end position and thus another Adjustability of the web property through this sectional actuators is retained.

A possible criterion for the adjustment of the Actuator with machine-wide effect For example, the web property could be the deviation of the Average of the sectional actuators from their Be in the middle position.

Another advantageous criterion for implementation The distance could influence the machine of the maximum or minimum standing Actuator from their possible end position represent. The aim of a correction by the The machine-wide actuator is then the distance of the maximum standing actuator from possible maximum and the minimum standing Actuator from the possible minimum as much as possible equalize.

Instead of the position of the actuators as Controlled variable, can for example also a certain measured suspension property at the exit of a Mixer or any other result by the Position of a sectional actuator is influenced, used. Can also be used as Controlled variable serve a web property that with the Position of the actuator directly or indirectly correlated. Another way to achieve the information about the position of the sectional Actuators can be made from a simple Calculation of the history of the control commands to the individual actuators.

Further embodiments of the invention are in the Subclaims to the first device claim, in the subclaims to the first procedural claim and specified in the following description of the figures.

Figur 1+2:

Grafische Darstellungen zweier erfindungsgemäßen Regelsituationen;

Figur 3:

Schematische Darstellung einer erfindungsgemäßen Regelvorrichtung mit Flächengewichtsregelung mit Verdünnungszufuhr in der Hochkonzentrationsleitung;

Figur 4:

Schematische Darstellung einer erfindungsgemäßen Regelvorrichtung mit Flächengewichtsregelung mit Verdünnungszufuhr in der Niederkonzentrationsleitung;

Figur 5:

Schematische Darstellung einer erfindungsgemäßen Regelvorrichtung mit Flächengewichtsregelung mit einer Querverbindung zwischen der Hoch- und Niederkonzentrationsleitung.

Further features and advantages of the invention result from the following description of preferred exemplary embodiments with reference to the drawing.

Figure 1 + 2:

Graphic representations of two control situations according to the invention;

Figure 3:

Schematic representation of a control device according to the invention with basis weight control with dilution in the high concentration line;

Figure 4:

Schematic representation of a control device according to the invention with basis weight control with dilution supply in the low concentration line;

Figure 5:

Schematic representation of a control device according to the invention with basis weight control with a cross connection between the high and low concentration line.

In Figure 1 is a graphical representation of a Control situation according to the invention shown. The Figure 1a shows the representation of a Web property transverse profile. It is on the abscissa Position in relation to the machine width plotted. The ordinate shows the values of the orbital property. For example, this can be the Grammage, ash content, web thickness or other web properties specified above act.

The course of the current web property is in the Curve 1 is shown, while the dashed line 2 represents the ideal setpoint for this web property. The course of the web property shown by the Curve 1 shows the deviations of the web property from ideal web properties cross profile, as in normal operation of a paper machine. The means the corrections to the existing ones Actuators for optimizing the web properties cross profile are already as far as possible performed.

The current figure is in FIG. 1b below Actuator situation of five selected Actuators shown over the web width. On the The abscissa is again the position with respect to the Machine width plotted and the ordinate shows a Measure for the adjacent setting of the respective Actuator. Lines 3 and 4 show the maximum or minimum possible end position of the respective actuators. With the arrows 5.1 to 5.5 is the respective setting situation of the individual Actuators specified, with only the length the arrows, i.e. the distance of the arrowhead from the Baseline 6, the setting position of the actuator represents. In the current situation shown the Actuators can be seen that everyone Actuators in the top half of their Adjustment range between lines 3 and 4 are located, the actuators 5.3 even his Has reached maximum position.

In addition to the sectional positions Actuators 5.1 to 5.5 is the one for machine-wide adjustment of the web property responsible actuator 7 with its current Position shown, which in turn is the baseline 6 indicates for the sectional actuators 5.1 to 5.5.

According to the invention is now triggered Event an adjustment of the actuator position 7, the one across the entire width of the web Actuator, triggered and a parallel shift all sectional actuator positions 5.1 to 5.5 causes.

This situation is shown in Figure 1c. Here the controlled variable of the actuator 7 is reduced, so that the basis for the sectional actuators 5.1 to 5.5 is raised, resulting in a corresponding Settling phase the individual manipulated variables 5.1 to 5.5 be reduced and back in a medium Adjustment range. Is in this control range now again an optimal controllability of the sectional Actuators reached.

The triggering event for the adjustment of the machine-wide actuator can for example reaching an end position of a represent sectionally acting actuator. As well However, a permanent regulation of the machine-wide actuator take place such that the control mechanism tries for the sectional acting actuators as large a distance as possible the maximum or minimum standing Actuators from the maximum respectively Effect minimum position. In this respect it is from Advantage that usually the linear control range of an actuator in the middle range is and thereby simplifies the control behavior of the entire system can be achieved.

A situation similar to that in FIG. 2 is shown in FIG Figure 1 shown. Figure 2a is identical to figure 1a. In FIG. 2b, the mean value is also 8 the sum of all actuator positions 5.1 to 5.5 sectional actuators. It's closed recognize that represented by line 8 Average in that shown in Figure 2b Situation from the middle position between Maximum setting 3 and minimum setting 4 of the Actuators deviate.

This deviation or a specific, predetermined one The size of this deviation can be a triggering event for the adjustment of the machine-wide acting Actuator can be viewed. Is that machine-wide acting actuator in its manipulated variable 7 now led accordingly, so the average of the individual, sectionally acting actuators 5.1 to 5.5 again in the middle area between the Maximum setting 3 and minimum setting 4 of the sectionally acting actuators.

According to the invention, it is possible to recycle the sectional actuators after a change in web-wide actuator over the normal To carry out the controlled system. However, this requires that due to the relatively long running times of the paper web inside a paper machine until measuring the considered a long term and so that a somewhat sluggish regulation arises.

A more favorable situation arises if simultaneously with the adjustment of the web width acting actuator for a particular Railway property from the control system one command to one simultaneous and across the machine width uniform countermeasures of all sectionally acting Actuators is given. This countermeasure through all sectional actuators should be included if possible the same amount, however opposite effect to the adjustment of the generate machine-wide actuator. On this way there is little to none Emigration of the entire profile from the target state it acts. In addition, the settling time is reduced in an optimal control situation considerably.

In Figure 3 is an inventive Control device for a basis weight control with With the help of a headbox controlled by density shown.

The stock density-controlled headbox 10 receives the stock suspension with a high concentration C _H , which is divided into individual sectional streams 15.1, 15.2 and 15.3 before entering the headbox via a high concentrate line 15, which is fed by a regulated pump 18. For reasons of clarity, only three partial streams are shown in this illustration. In real conditions, however, the number of headbox sections is much higher. Before entering the headbox, the individual sectional streams 15.1 to 15.3 are supplied with individual, volume flow-controlled dilution streams 16.1 to 16.3 with a low concentration C _L.

The volume flow control of the sectional Dilution streams 16.1 to 16.3 take place through Throttling devices 23.1 to 23.3, which are sectional Actuators act. The setting of the sectional Actuators are carried out via control lines 28.1 - 28.3, which is generated by a corresponding computing unit 31 to be served.

In the illustrated embodiment, this will assumed that the bringing together of the individual Mixed flows of high and low concentration Mixer is used as in the patent application DE 42 11 291 or DE 42 11 290 is described. In In this case, one valve per section is sufficient to use a constant, to obtain the total sectional volume flow. It lies however also within the scope of the invention the control of sectional total volume flows through the Interaction between two throttle devices cause. The latter mode of operation is exemplified in patent applications DE 40 19 593 and DE 41 12 347 shown.

The headbox 10 gives its stock suspension as a machine-wide layer on a sieve 11 on which in the further course of the machine a fiber web is formed by draining them heavily and dried and at the end of the machine on a roll 13 is wound up. Before winding on the roll 13 is the basis weight cross section via a measuring frame 12 measured on the paper web and via the measuring line 14 the process control system 30 with its Arithmetic unit fed. The computing unit of the Process control system 30 calculated on the basis of the measured Cross section the necessary adjustment of the sectional Actuators, in this case the throttling devices 23.1 to 23.3, and gives this information about the Line 33 to the computing unit 31 from where the setting of the actuators 23.1 to 23.3 via the overall control line 28, which is in the Individual control lines 28.1 - 28.3 divided becomes. Within the scope of the invention it is also possible Control of the individual actuators via Bus system.

The process control system 30 also receives a or several measuring points provide information about the Consistency of the stock suspension in the headbox the connecting line 24 and / or information about the Retention behavior over the data line 25. Continued the process control system 30 controls the large ones Suspension flows via the pumps 18 and 19 in the Supply lines 15 and 16 of the headbox. For a more precise adjustment of the stock suspension feed can, as happened in the present example, a Flow meter 22 provided in the dilution stream become; the same can be done for all dosing systems in this control system can be realized.

According to the invention, the process control system 30 additionally via a further data line 32 Information about the position of the throttling devices 23.1 to 23.3 communicated. This information can either as calculated here or over appropriate measuring equipment directly to the Actuators of the throttle devices 23.1 to 23.3 be removed. Based on the calculated Position of the sectional throttling devices 23.1 to 23.3 the process control system calculates a necessary one Change in the concentration of the thick matter in the Line 15 and opens or closes a machine acting actuator. In this case it is Throttle valve 20 in the additional supply of a Dilution fluid via the feed line 17 to High concentrate line 15. The supply line 17 leads either fresh water or dilution water, with whose help is the concentration of the thick matter can be changed. Through this change a machine-wide increase or decrease in Concentration of the stock suspension causes, which Position the actuators 23.1 to 23.3 again in the Close to the desired normal position can. According to the invention, this can be done either via the normal controlled system, by measuring the result on Measuring frame 12 take place. However it is possible to advance the necessary control result calculate and accordingly a simultaneous Adjustment of the sectional actuators 23.1 to 23.3 to effect. For more precise dosing of the supplied Dilution fluid via line 17 is a Flow meter 21 is provided, which via the line 26th is connected to the process control system 30.

Another alternative to designing this control system according to the invention can consist in that the supply line 17 with fresh water or pure White water is supplied and to the supply line 16 the low concentrate supply 16 is connected. This The embodiment is shown in FIG. 4.

Another possibility for machine-wide control the consistency in the supply lines of the high and / or Low concentrate lines 15, 16 to Headbox can consist of these two Feed lines via a further delivery line 17 connect with each other. Now becomes necessary Concentration in the high concentrate line 15 to reduce, so only the amount of Suspension supply from the low concentrate line 16 to the high concentrate line 15 increased or reverse case lowered. For example through a speed-controlled pump 20 in connection done with a flow meter 21. Such one Execution is shown in FIG. 5.

Measures are described in FIGS. 3, 4 and 5 in order to change the consistency in lines 15 (Q _H ) and 16 (Q _L ).

It can also make sense to change the ratio of Q _L / Q _H without supplying additional white water (line 17), for example by regulating the pumps 18 and 19 via this ratio.

The volume flows Q _L and Q _H can be measured with a flow meter and / or calculated from operating data.

With all of the embodiments shown, it is possible compared to the prior art, essential better results in headbox control to get a paper web and thus the total paper quality achievable with this device improve.

LIST OF REFERENCE NUMBERS

1

Web property transverse profile

2

setpoint

3

Maximum position of the actuators

4

Maximum position of the actuators

5.1, 5.2, 5.3, 5.4, 5.5

Position of the sectional acting actuators

6

baseline

7

Machine width position acting actuator

8th

Mean of Actuator positions

10

headbox

11

scree

12

Measuring frame (medium)

13

role

14

Measurement line

15

High concentrate line

15.1, 15.2, 15.3

Sektionalströme

16.1, 16.2, 16.3

Low concentrate line

17

supply line

18, 19

pump

20

Throttle valve or pump

21, 22

flowmeter

23.1, 23.2, 23.3

Throttling devices (actuators)

24

connecting line

25

data line

26

Measurement line

28,34,35

control line

30

process control system

31

computer unit

32.33

data line

Claims (37)

1. Apparatus for the open-loop or closed-loop control of at least one web property transverse profile (1) of at least one web property of a paper or board web in the production process of a paper or board machine, comprising the following features:

   1.1 at least one first means (12) is provided for measuring the web property transverse profile (1) of the web property and for producing corresponding measured signals;

   1.2 a computer unit is provided for processing the measured signals for the purpose of calculating correction values to achieve the desired web property transverse profile (1) of the web property;

   1.3 a large number of actuating elements (23.1-23.3) is provided for influencing the web property transverse profile (1) of the web property section by section, it being possible to determine the position of one or more of the large number of the actuating elements (23.1-23.3) for influencing this web property section by section;

   1.4 at least one second means (30, 33, 31, 28, 28.1-28.3) is provided for the open-loop or closed-loop control of one or more of the large number of actuating elements (23.1-23.3) for influencing the web property transverse profile (1) of the web property section by section, taking into account the calculated correction values;
   characterized by the following features:

   1.5 that at least one adjustable means (18, 19, 20) is provided for influencing the web property transverse profile (1) of the web property over the web width;

   1.6 that a means (30, 32, 33, 35, 27) is provided for including the information about the position of one or more of the large number of actuating elements (23.1-23.3) for influencing the web property transverse profile (1) of the web property section by section for the closed-loop or open-loop control of one or more of the means (18, 19, 20) for influencing the web property transverse profile (1) of the web property over the web width.
2. Apparatus according to Claim 1, characterized in that the large number of actuating elements (23.1-23.3) for influencing the at least one web property section by section are the actuating elements of the headbox slice.
3. Apparatus according to Claim 1, characterized in that the large number of actuating elements (23.1-23.3) for influencing the at least one web property section by section are actuating elements of the mixers of a headbox (10) whose consistency and/or volume flow is controlled section by section.
4. Apparatus according to Claim 1, characterized in that the large number of actuating elements (23.1-23.3) for influencing the at least one web property section by section are actuating elements for the closed-loop control of a sectional supply of a fluid into the stock suspension flow within the headbox (10) itself.
5. Apparatus according to one of Claims 1-4, characterized in that the first means (12) for the direct or indirect measurement of the at least one web property transverse profile (1) is a measuring frame (12) extending transversely over the machine width.
6. Apparatus according to one of Claims 1-4, characterized in that the first means (12) for the direct or indirect measurement of the at least one web property transverse profile (1) is positioned between the drying section and the reel-up of the paper web.
7. Apparatus according to one of Claims 1-4, characterized in that the first means (12) for the direct or indirect measurement of the at least one web property transverse profile (1) is positioned in the outlet area of the headbox (10).
8. Apparatus according to one of Claims 1-4, characterized in that the first means (12) for the direct or indirect measurement of the at least one web property transverse profile (1) is positioned in the area of the wet end.
9. Apparatus according to one of Claims 1-4, characterized in that the first means (12) for the direct or indirect measurement of the at least one web property transverse profile (1) is positioned in the area of the drying section.
10. Apparatus according to one of Claims 1-9, characterized in that the second means (30, 33, 31, 28, 28.1-28.3) for the open-loop or closed-loop control of one or more of the large number of actuating elements (23.1-23.3) for influencing the at least one web property transverse profile (1) section by section is a process control system (30).
11. Apparatus according to one of Claims 1-10, characterized in that the means (30, 32, 33, 35, 27) for incorporating the information about the position of one or more of the large number of actuating elements (23.1-23.3) for influencing the at least one web property section by section for the closed-loop or open-loop control of the means for influencing the at least one web property over the machine width is a program or program module which uses the actuating commands from the means for the open-loop or closed-loop control to the large number of adjustable means for influencing the at least one web property transverse profile section by section to draw conclusions about the current position of one or more of the large number of actuating elements (23.1-23.3) for influencing the at least one web property transverse profile (1) section by section.
12. Apparatus according to Claim 10, characterized in that the second means (30, 33, 31, 26, 28.1-28.3), which measures the information about the position of a number of or all of the means of the large number of adjustable means (23.1-23.3) for influencing the at least one web property section by section for the closed-loop or open-loop control of the means for influencing the at least one web property over the machine width, is a measuring system for the position of the adjustable means for influencing the at least one transverse profile of the at least one web property section by section on the current position of the large number of adjustable means for influencing the at least one transverse profile of the at least one web property section by section, and a feedback means (32) is provided to feed the information about the position back into the process control system (30).
13. Apparatus according to one of Claims 1-12, characterized in that at least one adjustable means (18, 19, 20) for influencing at least one web property over the machine width is a pump (18, 19) and/or a restrictor valve (20) in a high-consistency and/or low-consistency line to the headbox (10).
14. Apparatus according to one of Claims 1-12, characterized in that at least one adjustable parameter for influencing at least one web property over the machine width is the concentration of stock suspension in the high-consistency and/or the low-consistency line to the headbox (10).
15. Apparatus according to one of Claims 1-14, characterized in that at least one of the web properties which is observed and/or influenced is the grammage.
16. Apparatus according to one of Claims 1-14, characterized in that at least one of the web properties which is observed and/or influenced is the formation.
17. Apparatus according to one of Claims 1-14, characterized in that at least one of the web properties which is observed and/or influenced is the ash content.
18. Apparatus according to one of Claims 1-14, characterized in that at least one of the web properties which is observed and/or influenced is the web thickness.
19. Apparatus according to one of Claims 1-14, characterized in that at least one of the web properties which is observed and/or influenced is the moisture content of the web.
20. Apparatus according to one of Claims 1-14, characterized in that at least one of the web properties which is observed and/or influenced is the opacity of the web.
21. Apparatus according to one of Claims 1-14, characterized in that at least one of the web properties which is observed and/or influenced is the roughness of the web.
22. Apparatus according to one of Claims 1-14, characterized in that at least one of the web properties which is observed and/or influenced is the fibre orientation.
23. Method for the open-loop or closed-loop control of at least one web property transverse profile (1) of at least one web property of a paper or board web in the production process of a paper or board machine, comprising the following features:

    23.1 measuring the web property transverse profile (1) of the web property and producing corresponding measured signals;

    23.2 processing the measured signals in a computer unit with the calculation of correction values to achieve the desired web property transverse profile (1) of the web property;

    23.3 adjusting one or more of a large number of actuating elements (23.1-23.3) for influencing the web property transverse profile (1) of the web property section by section on the basis of the calculated correction values;

    23.4 determining the position of one or more of the large number of actuating elements (23.1-23.3) for influencing the web property transverse profile (1) of the web property section by section;
    characterized by the following features:

    23.5 processing and including the position of one or more of the large number of actuating elements (23.1-23.3) for influencing the web property transverse profile (1) of the web property section by section in a computer unit, with the calculation of a correction value of at least one adjustable means (18, 19, 20) for influencing the web property transverse profile (1) of the web property over the web width;

    23.6 correcting the web property transverse profile (1) of the web property by adjusting one or more of the means (18, 19, 20) for influencing the web property transverse profile (1) of the web property over the web width on the basis of the calculated correction value.
24. Method according to Claim 23, characterized in that, at least approximately at the same time as the adjustment of the at least one adjustable means (18, 19, 20) for influencing this web property over the web width, the actuating elements (23.1-23.3) for influencing this web property section by section are as a whole guided in the opposite direction.
25. Method according to one of Claims 23-24, characterized in that the position of the actuating elements (23.1-23.3) for influencing this web property section by section is calculated from the history of the previous actuating commands from the computer unit.
26. Method according to one of Claims 23-24, characterized in that the position of the actuating elements (23.1-23.3) for influencing this web property section by section is measured directly or indirectly on the actuating element (23.1-23.3).
27. Method according to one of Claims 23-24, characterized in that the web property considered is represented by the grammage.
28. Method according to one of Claims 23-24, characterized in that the web property considered is represented by the formation.
29. Method according to one of Claims 23-24, characterized in that the web property considered is represented by the ash content.
30. Method according to one of Claims 23-24, characterized in that the web property considered is represented by the web thickness.
31. Method according to one of Claims 23-24, characterized in that the web property considered is represented by the moisture content.
32. Method according to one of Claims 23-24, characterized in that the web property considered is represented by the opacity.
33. Method according to one of Claims 23-24, characterized in that the web property considered is represented by the roughness.
34. Method according to one of Claims 23-24, characterized in that the web property considered is represented by the fibre orientation.
35. Method according to Claim 27, characterized in that the position of the actuating elements (23.1-23.3) for influencing this web property section by section is calculated from the history of the previous actuating commands from the computer unit.
36. Method according to one of Claims 23-35, characterized in that the correction to the web property is performed by adjusting the other singular or plural adjustable means (18, 19, 20) for influencing this web property over the web width, in such a way that, following the re-correction by the actuating elements (23.1-23.3) for influencing section by section, none of these actuating elements (23.1-23.3) is in an end position.
37. Method according to one of Claims 23-35, characterized in that, to calculate the magnitude of the correction of the web property by adjusting the adjustable means (18, 19, 20) for influencing over the web width, the average of the position of the actuating elements (23.1-23.3) for influencing section by section is used.

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