FI20206035A1 - Method of controlling caliper of the fiber web of a parent roll and production line for producing fiber webs - Google Patents

Abstract

The invention relates to a method of controlling the caliper of the fiber web (W) of a parent roll produced in a fiber web production line, comprising a head box (11), a forming section (12), a press section (13), a drying section (14), a calender (15), a coating section (16), a reel-up (18) for reeling the parent roll, an unwinding station (21) of a slitter-winder, a slitting section of the slitterwinder, a winding section (22) of the slitter-winder for winding customer roll. The caliper of the fiber web (W) is controlled before reeling the fiber web (W) onto the parent roll in the reel-up (18) as a function of the diameter of the customer roll.

Description

Method of controlling caliper of the fiber web of a parent roll and production line for producing fiber webs Menetelmä konerullan kuiturainan = kaliiperin kontrolloimiseksi ja valmistuslinja kuiturainojen valmistamiseksi Technical field In general, present invention relates to production of fiber webs, in particular to producing board webs. More especially the present invention relates to a method of controlling caliper of the fiber web of a parent roll according to preamble part of the independent method claim and to production line for producing fiber webs according to preamble part of the independent production line claim.

Background As known from the prior art in fiber web producing processes typically comprise an assembly formed by a number of apparatuses arranged consecutively in the process line. A typical production and treatment line comprises a head box, a wire section and a press section as well as a subsequent drying section and a reel-up. The production and treatment line can further comprise other sections and devices for finishing the fiber web, for example a sizer, a coating device and a calender. The production and treatment line also typically comprises at least one slitter-winder for forming customer rolls as well as a roll packaging apparatus. And as known, fiber webs, such as paper or board webs, S are manufactured in machines together forming a fiber web manufacturing line, N which may be hundreds of meters long. 2 S 30 In fiber web manufacturing lines, manufacturing operates as a continuous I process and the process is generally run with constant speed and with = constant basis weight, when producing selected fiber web grade. The finished 3 fiber web being output from the machine is wound with a reel-up around a S reeling shaft, i.e. a reel spool, into a parent roll (a machine roll), the diameter S 35 of which may be more than 5 meters, and which may weigh more than 160 tons. The purpose of the reeling is to transfer the fiber web from its planar manufacturing form into a form in which it can be handled more easily. The reel-up is thus a device that reels a material, which is produced as a continuous fiber web in a fiber web production line, into form of a roll; the parent roll. In the production process of the fiber web, the reeling is generally a first process part, wherein a continuous process is discontinued to be continued in sequences. The parent roll is formed around the reeling shaft that functions as a core of reeling, i.e. the fiber web on one parent roll around one reeling shaft has a beginning and an end.

The parent roll is wound up to be just as tight as to endure reeling, storage including roll transfers and later unwinding. Typically, the goal is for the parent roll tightness to decrease from inner layers to surface or, at least, to remain the same. It is known from prior art to define real-time parent reel or wound roll caliper and density by a measurement and calculation system. It is also known to define wound-in caliper profiles during reeling. One known system is described in WO patent application publication 02102693 A1. The reeling parameters: nip load, web tension and peripheral force, are determined based on f. ex. properties of paper or board, such as smoothness, stiffness, compressibility and friction coefficient, the parent roll size, handling method, storage time and running speed. The reeling parameters are typically only changed when the fiber web grade changes or if there are reeling problems. The web of the parent roll generated during manufacture is full-width and even more than 100 km long, so it must be cut into partial webs of a suitable width and length for customers and wound around cores into “customer rolls” before dispatch from the mill. As known, this slitting and winding of the web takes N place in a separate machine fitted to the purpose, i.e., a slitter-winder. In the N slitter-winder the parent roll is unwound in the unwinding station off the reeling 2 shaft and the broad web is slit with the slitting section into a number of narrower partial webs, which are wound with the winding section in the winder around z 30 winding spools such as cores into customer rolls. When the customer rolls are so ready, the slitter-winder is stopped and the rolls, or “set”, is removed from the 2 machine. After this, the process continues with the winding of anew set. These S stages are repeated periodically until the fiber web on the parent roll runs out N from the reeling shaft, at which point the parent roll is replaced and the operation restarts with the unwinding of a new parent roll from the reeling shaft.

Fiber webs, especially paper and board are available in a wide variety of types and can be divided according to basis weight in two grades: papers with a single ply and a basis weight of 25-300 g/m? and boards manufactured in one- or multi-ply technology and having a basis weight of 150-600 m/m?. It should be noted that the borderline between paper and board is flexible since board grades with lightest basis weights are lighter than the heaviest paper grades. Generally speaking, paper is used for printing and board for packaging. The main carton board grades are folding boxboard (FBB), white-lined chipboard (WLC), solid bleached board (SBS) and liquid packaging board (LPB). In general, these grades are typically used for different kinds of packaging of consumer goods. Carton board grades vary from one- up to five-ply boards (150-400 g/m?). The top side is usually coated with from one to three layers (20-40 g/m?), the back side has less coating or no coating at all.

Bulkiness i.e. relation of thickness of the fiber web to its grammage (basis weight) of board webs reduces during reeling and typically bulk loss is greatest in inner layers of the parent roll as the stresses inside the parent roll cause caliper losses. Additionally, some bulk loss may occur during winding in the slitter-winder. Due to this in board manufacturing board web is typically produced in caliper values exceeding the target value, even 5 %, in order to reach the target value also in the worst case. Thus, of the production time even over 90 % of time is run with caliper values that exceed the target value. This has a significant negative input also economically. These disadvantages and problems also increase, when the bulkiness of the fiber web increases.

N In EP publication 2107997 A1 is disclosed a method for winding continuous N web material to form a substantially fully compressed roll of the wound web 2 material so that the machine direction tension in the web is substantially uniform throughout the wound roll of web material. In the method a z 30 compensated WOT profile id generated and the compensated WOT profile so varies as a function of the wound roll diameter and the compensated WOT 2 profile is the WOT that is needed in the web as the web is being wound onto S the roll in order to provide the wound roll with a substantially uniform thru-roll N MD tension. In the method the compensated WOT profile can be converted to speed control based on a predetermined relation between winder speed and WOT for the web.

An object of the invention is to create a method of controlling caliper of the fiber web of a parent roll and a production line for producing fiber webs, in which the disadvantages and problems of prior art are eliminated or at least minimized. A particular object of the invention is to create a method of controlling caliper of the fiber web and a production line for producing fiber webs, in which the disadvantages and problems of prior art relating to running the production of the fiber web with caliper values exceeding the target values are eliminated or at least minimized. Summary In order to achieve the above mentioned objects, the method of controlling caliper of the fiber web according to the invention is mainly characterized by the features of the characterizing clause of the independent method claim and the production line for producing fiber webs according to the invention is mainly characterized by the features of the characterizing clause of the independent production line claim. Advantageous embodiments and features are disclosed in the dependent claims. In this description and in the claims by the expression “inner layers of a parent roll” is meant 10 %, advantageously 5 %, of the whole length of the fiber web N on the parent roll.

N 2 According to the invention in the method of controlling the caliper of the fiber N web of a parent roll produced in a fiber web production line comprising a head z 30 box, a forming section, a press section, a drying section, a calender, a coating so section, a reel-up for reeling a parent roll, an unwinding station of a slitter- S winder, a slitting section of the slitter-winder, a winding section of the slitter- S winder for winding a customer roll, the caliper of the fiber web of the parent roll is controlled as a function of the diameter of the customer roll.

According to an advantageous feature of the invention in the method at least one of the following running parameters of the production line: web speed i.e. production speed, headbox-flow, head-box consistency, coating weight of the coating paste and/or calender nip load is adjusted for reeling of the parent roll 5 to control the caliper of the fiber web. According to an advantageous feature of the invention in the method caliper of the fiber web to be wound as inner layers of the parent roll is adjusted to exceed a set target value of the caliper of the fiber web by adjusting the running parameter/-s. According to an advantageous feature of the invention in the method the finished parent roll is provided the fiber web with desired caliper as a function of the diameter of the customer roll, advantageously with constant caliper.

According to an advantageous feature of the invention the running parameter/- s is/are adjusted beginning at the latest at the time for the fiber web to be reeled as the inner most layer of the parent roll for a time-interval corresponding to reeling the inner layers of the parent roll. According to an advantageous aspect it is preferable if the running during a changing parameter is timed to correspond the time when running bottom or surface waste layers of the parent roll. According to an advantageous feature of the invention the running speed of the production line is decreased in order to provide fiber web with caliper N values exceeding the target value of the caliper of the fiber web for the inner 5 layers of the parent roll. N According to an advantageous feature of the invention to provide fiber web z 30 with caliper values exceeding the target value of the caliper of the fiber web for so the inner layers of the parent roll is provided by increasing the headbox-flow S and/or by increasing the head-box consistency and/or by increasing the S coating weight of the coating paste and/or by reducing thee calender nip load.

N According to an advantageous feature of the invention time interval for the run with adjusted running parameters for the run of the inner layers of the parent roll is defined advantageously by caliper data calculated based on data received from an on-line measurement means, advantageously sensors, at winding section of the slitter-winder.

The caliper data can be calculated based on calculation systems known as such, for example as described in WO patent application publication 02102693 A1. According to an advantageous feature of the invention the fiber web is produced in a fiber web production line further comprising a customer roll storage with a sample taking station and time interval for the run with adjusted running parameters for the run of the inner layers of the parent roll is defined advantageously by caliper measurement data received the sample taking station.

According to an advantageous feature of the invention the method comprises: a target setting step, in which target caliper data of the fiber web is set, a parameter selection step, in which the running parameters, web speed i.e. production speed, the headbox-flow and/or the head-box consistency, the coating weight of the coating paste to be applied onto the fiber web at the coating section and the calender nip load of the calender are selected and defined to produce a fiber web with the target caliper, a measurement step, in which the caliper data is received, a checking step, in which based on the received caliper data is checked whether the caliper of the fiber web as a function of the customer roll is desired, advantageously constant, in the customer roll, and if the caliper of the fiber web in the customer roll is not desired, N advantageously constant, the return branch is selected, and the diameter N dependent correction factor is changed in a factor changing step and the 2 selected running parameter/-s are changed accordingly in the parameter selection step. z 30 so According to an advantageous feature of the invention the method further S comprises: a sample measurement step , in which caliper data is received and S thereafter a sample checking step and based on the from the sample measurement step received caliper data is checked whether the caliper of the fiber web as a function the customer roll is desired, advantageously constant, in the customer roll and if the caliper of the fiber web in the customer roll is not desired, advantageously constant, an additional return branch is selected and the diameter dependent correction factor is changed in factor changing step and the selected running parameter/-s are changed accordingly in the parameter selection step.

According to the invention the production line for producing fiber webs comprises a head box, a forming section, a press section, a drying section, a calender, a coating section, a reel-up, an unwinding station of a slitter-winder, a slitting section of the slitter-winder, a winding section of the slitter-winder and measuring means, for example sensors, advantageously one-line measuring means, to measure the of the fiber web of the parent roll to calculate the caliper of the fiber web, for example based on calculation systems known as such, for example as described in WO patent application publication 02102693 A1, to be unwound in the unwinding station and/or to define the caliper of the fiber web to be wound to a customer roll in the winding section, wherein the production line further comprises a data-base and calculating device to collect and store the measurement data received from the measuring means and to calculate, for example as described in WO patent application publication 02102693 A1, and determine the caliper curve of the parent roll as a function of the diameter of the parent roll and to calculate the caliper as function of the diameter of the customer roll as out-put data sent as in-put data to a control device of the fiber web production line to adjust at least one of the following running parameters of the production line: web speed i.e. production speed, headbox-flow, head-box consistency, coating weight of the coating paste and/or calender nip load is adjusted for reeling of the parent roll to control the N caliper of the fiber web.

N 2 According to an advantageous feature of the invention the production line further comprises a customer roll storage and a sample taking station at the z 30 customer roll storage to take samples of the fiber web in order to define the so caliper of the fiber web. 3 S According to an advantageous aspect of the present invention the caliper of N the fiber web is controlled as a function of the diameter of the parent roll in unwinding in the unwinding station of the slitter-winder or additionally as a function of the diameter of the customer rolls of the set. Advantageously, the caliper is increased before the turn-up (change to new parent roll winding) in the reel-up and a set time increased caliper is reeled as the inner layers of the parent roll. There after the caliper is set to the target value. Thus, in unwinding the caliper of the unwound fiber web is with desired caliper as a function of the diameter of the parent roll, advantageously with constant caliper / the caliper of the fiber web to be unwound from a customer roll is with desired caliper as a function of the diameter of the customer roll, advantageously with constant caliper. Advantageously, time of running increased caliper is about 10% of the reeling of one parent roll in the reel-up.

According to an advantageous aspect of the invention based on caliper curve of the parent roll in unwinding in the unwinding station of the slitter-winder the caliper of the fiber web is adjusted by decreasing the production speed of the production line, typically2-3 %, if required even up to 10 %, such that the fiber web to be reeled as inner layers of the parent roll will have increased caliper to compensate the bulk loss of the reeling and winding. According to another advantageous aspect of the invention based on caliper curve of the customer roll set produced in the slitter-winder the caliper of the fiber web is adjusted by decreasing the production speed of the production line, typically 2-3 %, if required even up to 10 %, such that the fiber web to be reeled as inner layers of the parent roll will have increased caliper to compensate the bulk loss of the reeling and winding. Alternatively, to provide the increased caliper to the inner layers of the parent N roll the consistency of the head-box and/or flow at the slice of the head-box is N adjusted correspondingly for the inner layers of the parent roll. In case a multi- 2 ply fiber web is produced, for example only the consistency of the middle layer head-box and/or flow at the slice of the middle-layer head-box is adjusted. z 30 so Alternatively, to provide the increased caliper to the inner layers of the parent S roll the coating weight of the coating paste to be applied onto the fiber web at S the coating section is adjusted correspondingly for the inner layers of the parent roll.

Alternatively, to provide the increased caliper to the inner layers of the parent roll the calender nip load is adjusted correspondingly for the inner layers of the parent roll.

By the invention and its advantageous features many advantages are achieved: amount of raw material used, and energy consumed decreased several percent and still the target values of the fiber web produced are achieved. Thus, significant environmental and economical saving are also achieved.

Brief description of the drawings In the following the invention is explained in detail with reference to the accompanying drawing to which the invention is not to be narrowly limited. In figure 1 is shown schematically an advantageous example of a fiber web production line according to the invention. In figure 2 is shown a schematical example as flowchart illustrating steps of the method of controlling caliper of a fiber web of a parent roll. In figures 3A-3B is schematically shown example graphs of caliper losses, in figure 3A in accordance prior art and in figure 3B in accordance with the invention.

S N In figures 4A-4B is schematically shown portion of one caliper run of a parent 2 roll, in figure 4A in accordance prior art and in figure 4B in accordance with the invention. z 30 so During the course of the following description like numbers and signs will be S used to identify like elements according to the different views which illustrate S the invention and its advantageous examples. In the figures some repetitive reference signs have been omitted for clarity reasons.

Detailed description In figure 1 is very schematically shown a fiber web production line which comprises a head box 11, a forming section 12, a press section 13, a drying section 14, a calender 15, a coating section 16 with drying equipment 17, a reel-up 18, a parent roll storage 19, an unwinding station 21 of a slitter-winder, a slitting section (not shown) of the slitter-winder, a winding section 22 of the slitter-winder and a customer roll storage 23, as well as a packaging section

24. In the production line there are also guide rolls 10, 20 for guiding and supporting the fiber web W and/or the fabric F supporting the web W. The fiber web W is typically supported by fabrics during forming, pressing and drying. The production line comprises measuring means 31, for example sensors, advantageously one-line measuring means, with a calculation system to measure and calculate for example as described in WO patent application publication 02102693 A1, the caliper of the fiber web W of the parent roll to be unwound in the unwinding station 21 and/or to define the caliper of the fiber web to be wound to a customer roll in the winding section 22. The production line may also comprise sample taking stations 32 at the parent roll storage 19 and/or at the customer roll storage 23 to take samples of the fiber web in order to define the caliper of the fiber web W. The production line further comprises a data-base and calculating device 33 to collect and store the caliper data received from the measuring means with the calculation system and/or from the sample taking stations received information and to calculate and determine the caliper curve of the parent roll and/or to calculate the caliper as function of the diameter of the parent roll / the customer roll as out-put data sent as in- N put data to a control device 34 of the fiber web production line to control N production speed of the fiber web production line in order to decrease the 2 production speed during reeling of the inner layers of the parent roll in the reel- up 18 to increase caliper and bulkiness temporarily for the inner layers of the z 30 parent roll to provide a parent roll with desired, advantageously constant target so caliper fiber web as a function of the diameter of the parent roll for unwinding 3 in the unwinder station 21 of the slitter-winder.

S N In figure 2 is shown a schematical example as a flowchart illustrating steps of the method of controlling caliper of a fiber web of a parent roll. Each fiber web grade has grade-based correction factor. In the target setting step 41 of the method the target caliper data of the fiber web is set and thereafter in the parameter selection step 42 the running parameters, web speed i.e. production speed, headbox-flow and/or head-box consistency, coating weight of the coating paste to be applied onto the fiber web at the coating section and/or calender nip load of the calender for the fiber web production line are selected and defined to produce a fiber web with the target caliper. In the measurement step 43 caliper data (advantageously calculated based on on-line measurement results with a calculation system received form the of a parent roll at the unwinding section of the slitter-winder) is received and thereafter in the checking step 44 based on the received caliper data is checked whether the caliper of the fiber web is desired as a function of the diameter of the parent roll/the customer roll, advantageously constant in the parent roll/in the customer roll. If the caliper of the fiber web in the parent roll is not desired as a function of the diameter of the parent roll/the customer roll, advantageously constant the return branch 51 i.e. "NO? is selected and the diameter dependent correction factor is changed in factor changing step 45 and the selected running parameter/-s are changed accordingly in the parameter selection step

42. Additionally (or alternatively) in sample measurement step 46 caliper data (advantageously calculated based on on-line caliper data received form the of a sample taking station) is received and thereafter in the sample checking step 47 based on the from the sample measurement step 46 received caliper data is checked whether the caliper of the fiber web is desired as a function of the diameter of the parent roll/the customer roll, advantageously constant in the parent roll/in the customer roll. If the caliper of the fiber web in the parent roll is not desired, advantageously constant, the additional return branch 52 i.e.

N "NO” is selected and the diameter dependent correction factor is changed in N factor changing step 45 and the selected running parameter/-s are changed 2 accordingly in the parameter selection step 42. In case the caliper is desired as a function of the diameter of the parent rollithe customer roll, z 30 advantageously constant in the parent roll the continuation branch 53 "YES? is so selected and the production is continued with set parameters.

O 3 S According to an advantageous example of the invention, here explained with N reference to the examples of figures 1 — 2, in the method the caliper of the fiber web W of the parent roll is controlled as a function of the diameter of the parent roll. In the method at least one of the following running parameters of the production line: web speed i.e. production speed, headbox-flow, head-box consistency, coating weight of the coating paste and/or calender nip load is adjusted for reeling of a parent roll such, that caliper of the fiber web W to be wound as inner layers of the parent roll exceeds the target value and desired caliper as a function of the diameter of the parent roll/the customer roll, advantageously constant caliper of the fiber web of the parent roll is achieved. Thus, the parameter/-s are adjusted beginning at the time for the fiber web W to be reeled as the inner most layer of the parent roll for a time-interval corresponding to reeling the inner layers of the parent roll. Advantageously, the running speed of the production line is decreased in order to run fiber web W with “over caliper” i.e. with caliper values exceeding the target value of the caliper of the fiber web W for the inner layers of the parent roll. The “over caliper” run is also achieved by increasing the headbox-flow, by increasing the head-box consistency, by increasing the coating weight of the coating paste and/or by reducing thee calender nip load. The time interval needed by the “over caliper” run of the inner layers of the parent roll is defined advantageously by measurement data received from an on-line measurement means 31, advantageously sensors, with the calculation system at the unwinding station 21 of the slitter-winder. Additionally or alternatively, the time interval needed by the “over caliper’ run of the inner layers of the parent roll is defined by measurement data received from an on-line measurement means 31, advantageously sensors, with the calculation system at winding section 22 of the slitter-winder and/or caliper measurement data received from a sample taking station 32 at the parent roll storage 19 and/or at the customer roll storage 23.

S N In figures 3A-3B is schematically shown example graphs of caliper losses, in 2 figure 3A in accordance prior art and in figure 3B in accordance with the invention. In X-axis is shown diameter of a parent roll in mm and in Y-axis is z 30 shown caliper in um. In figures 3A ja 3B graphs 61A, 61B indicate the caliper so of the fiber web before the reeling stage in the reel-up, graphs 62A, 62B the S caliper of the fiber web in the parent roll, graphs 63A, 63B the caliper of the S fiber web in the winding stage in the winding section of the slitter-winder and the graphs 64A, 64B indicate the target value of the caliper of the fiber web. In the reference numerals by letter A is indicated the values achieved by prior art and by letter B the values achieved by the invention. As can be seen from figure 3A in prior art systems the difference between the target value 64A of the caliper and the caliper used 61A-63A is large-scale but as can be seen from the figure 3B by the invention the difference between the target value 64B of the caliper and the caliper used 61B-63B is much smaller scale, and the difference between the required target values, graphs 64A, 64B of the prior art and the invention is great and thus, the situation has significantly improved. In figures 4A-4B is schematically shown portion of over caliper run of a parent roll, in figure 4A in accordance prior art and in figure 4B in accordance with the invention. As can be seen from figure 4A in prior art the running time in over caliper is about 90 % of the running time of the parent roll unwinding but in the invention as can be seen from figure 4B the running time in over caliper is only about 10 % of the running time of the parent roll unwinding and thereby, the situation has significantly improved. Graphs 65A, 65B illustrate the diameter of the parent roll as function of time and the covered areas 66A, 66B illustrate the portion of over caliper run. In the description in the foregoing, although some functions have been described with reference to certain features and examples, those functions may be performable by other features and examples whether described or not. Although features have been described with reference to the certain examples, those features may also be present in other examples whether described or not. Above only some advantageous examples of the inventions have been N described to which examples the invention is not to be narrowly limited and N many modifications and alterations are possible within the invention.

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Claims (1)

1. Claims:

   1. Method of controlling the caliper of the fiber web (W) of a parent roll produced in a fiber web production line, comprising a head box (11), a forming section (12), a press section (13), a drying section (14), a calender (15), a coating section (16), areel-up (18) for reeling the parent roll, an unwinding station (21) of a slitter-winder, a slitting section of the slitter-winder, a winding section (22) of the slitter-winder for winding customer rolls, characterized in that the caliper of the fiber web (W) is controlled before reeling the fiber web (W) onto the parent roll in the reel-up (18) as a function of the diameter of the customer roll.

   2. Method according to claim 1, characterized in that in the method caliper of the fiber web (W) to be wound as inner layers of the parent roll is adjusted to exceed a set target value of the caliper of the fiber web by adjusting at least one of the following running parameters of the production line: web speed i.e. production speed, headbox-flow, head- box consistency, coating weight of the coating paste and/or calender nip load.

   3. Method according to claim 1 or 2, characterized in that in the method the finished parent roll is provided the fiber web with desired caliper as a function of the diameter of the customer roll, advantageously with constant caliper.

   S N 4. Method according to claim 2 or 3, characterized in that the running 2 parameter/-s is/are adjusted at the latest beginning at the time for the fiber web (W) to be reeled as the inner most layer of the parent roll for z 30 a time-interval corresponding to reeling the inner layers of the parent so roll. 3 S 5. Method according to any of claim 2 - 4, characterized in that to, N characterized in that the running speed of the production line is decreased in order to provide fiber web (W) with caliper values exceeding the target value of the caliper of the fiber web (W) for the inner layers of the parent roll.

   6. Method according to any of claims 2 - 5, characterized in that to provide fiber web (W) with caliper values exceeding the target value of the caliper of the fiber web (W) for the inner layers of the parent roll is provided by increasing the headbox-flow and/or by increasing the head- box consistency and/or by increasing the coating weight of the coating paste and/or by reducing the calender nip load.

   7. Method according to any of claims 2 - 6, characterized in that time interval for the run with adjusted running parameters for the run of the inner layers of the parent roll is defined advantageously by caliper data received from an on-line measurement means (31), advantageously sensors, with a calculation system at winding section (22) of the slitter- winder.

   8. Method according to any of claims 2 - 7, characterized in that the fiber web (W) is produced in a fiber web production line further comprising a customer roll storage (23) with a sample taking station (32) and that time interval for the run with adjusted running parameters for the run of the inner layers of the parent roll is defined advantageously by caliper measurement data received the sample taking station (32).

   9. Method according to any of claims 1 - 8, characterized in that the N method comprises: N a target setting step (41), in which target caliper data of the fiber web is 2 set, a parameter selection step (42), in which the running parameters, web z 30 speed i.e. production speed, the headbox-flow and/or the head-box so consistency, the coating weight of the coating paste to be applied onto S the fiber web at the coating section and the calender nip load of the S calender are selected and defined to produce a fiber web with the target caliper, a measurement step (43), in which the caliper data is received,

   a checking step (44), in which based on the received caliper data is checked whether the caliper of the fiber web as a function of the diameter the customer roll is desired, advantageously constant in the customer roll, and that if the caliper of the fiber web in the customer roll is not desired, advantageously constant, the return branch (51) is selected and the diameter dependent correction factor is changed in a factor changing step (45) and the selected running parameter/-s are changed accordingly in the parameter selection step (42).

   10. Method according to any of claims 1 - 9, characterized in that the method further comprises: a sample measurement step (46), in which caliper data is received and thereafter a sample checking step (47) and that based on the from the sample measurement step (46) received caliper data is checked whether the caliper of the fiber web as a function of the diameter of the customer roll is desired, advantageously constant, in the customer roll and that if the caliper of the fiber web in the customer roll is not desired, advantageously constant, an additional return branch (52) is selected and the diameter dependent correction factor is changed in factor changing step (45) and the selected running parameter/-s are changed accordingly in the parameter selection step (42).

   11. Production line for producing fiber webs comprising a head box (11), a forming section (12), a press section (13), a drying section (14), a N calender (15), a coating section (16), a reel-up (18) for reeling a parent N roll, an unwinding station (21) of a slitter-winder, a slitting section (not 2 shown) of the slitter-winder, a winding section (22) of the slitter-winder for winding customer rolls and measuring means (31), for example z 30 sensors, with a calculation system, advantageously on-line measuring so means, to define the caliper of the fiber web to be wound to a customer S roll in the winding section (22), characterized in that the production line S further comprises a data-base and calculating device (33) to collect and store the caliper data received from the measuring means and to calculate and determine the caliper curve of the parent roll as a function of the diameter of the parent roll and to calculate the caliper as function of the diameter of the customer roll as out-put data sent as in-put data to a control device (34) of the fiber web production line to adjust at least one of the following running parameters of the production line: web speed i.e. production speed, headbox-flow, head-box consistency, coating weight of the coating paste and/or calender nip load such, that caliper of the fiber web (W) to be wound as inner layers of the parent roll is adjusted to exceed a set target value of the caliper of the fiber web by adjusting.

   12. Production line according to claim 11, characterized in that the production line further comprises a customer roll storage (23) and a sample taking station (32) at the customer roll storage (23) to take samples of the fiber web in order to define the caliper of the fiber web (W).

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