SYSTEM FOR OVERALL CONTROL OF THE DIFFERENT TRANSVERSE PROFILES IN A PAPER WEB MANUFACTURED BY MEANS OF A MACHINE FOR THE MANUFACTURE OF A WEB MATERIAL, SUCH AS A BOARD OR PAPER MACHINE AND/OR A FINISHING MACHINE

Abstract: A method for the control of the transverse profiles of a web (W) manufactured by means of a machine for the manufacture of a web material, such as a board or paper machine, and/or treated by means of a finishing machine. In the method, the transverse caliper and grammage profiles (cp, bp) and/or the moisture profile of the web (W) is/are measured. The actuators (44, 54, 47, 47a, 47b) acting upon said profiles are regulated by means of these signals (m3, m4) of measurement. In view of optimizing the quality of the web (W) to be produced, the reel formation, and the runnability of the machine, in the method, the transverse tension profile (tp) of the web (W) to be manufactured and/or treated is measured. Based on the measurement of the tension profile (tp), set profiles (s2, s3, s4) are formed, by whose means one or several actuators (12, 13, 14; 36, 44, 54, 61) of the profile regulation are controlled.

Description: System for overall control of the different transverse profiles in a paper web manufactured by means of a machine for the manufacture of a web material, such as a board or paper machine and/or a finishing machine The present invention concerns a method for the control of the transverse profiles of a web manufactured by means of a machine for the manufacture of a web material, such as a board or paper machine, and/or treated by means of a finishing machine, in which method the transverse caliper and grammage profiles and/or the moisture profile of the web is/are measured, the actuators acting upon said profiles being regulated by means of the signals of measurement of said profiles. As is known from the prior art, the various property profiles of a web manufactured or treated by means of machines for the manufacture of a web material, in particular by means of paper machines and by means of on-line finishing devices connected to them or by means of separate off-line finishing devices, profiles such as grammage, fibre-orientation, moisture, and thickness profiles, are controlled by means of various modes of regulation, the aim being a final product of a quality as high as possible and good runnability of the machines. Earlier, the significance of the transverse tension profile of a paper web both for the final product and for the runnability of the machines has been realized, but, as regards their fields of application, the prior-art methods for the control of the tension profile of the web have been small-scale partial solutions, in which the papermaking process and its optimization both in view of the final product produced and in view of the runnability of the machines have not been taken into account as a whole. In prior-art paper machines and finishing machines, attempts are made to produce a web whose moisture, grammage, caliper, and fibre-orientation profiles in the cross direction are as uniform as possible. The prior-art processes of manufacture accom¬ plish this objective, as a rule, so that the tension of the web to be produced in the cross direction of the web varies to a substantial extent, typically so that the tension is in the middle of the web about 300...400 N/m and in the lateral areas of the web about 100 N/m, which results in the drawbacks which will be described in more detail later. The starting point and the basis of the invention has been the realization of the significance of a uniform tension profile of the paper web, which significance has been divided into five factors in the following: 1. runnability in the paper machine 2. quality of the machine reel 3. runnability and quality of the roll from the slitter- winder 4. runnability in finishing 5. quality of the final product. In the following, the factors listed above will be dealt with in more detail while using the same numerals. 1. Since every portion of the web must always be in a tensioned state in the machine direction in a paper machine, when the running takes place with a uniform tension, the average tension can be minimized and, thus, the preferred draw differ¬ ences and web tension can be determined specifically for each paper grade. For example, when a maximal stretch at break is aimed at, the web should be run preferably with a low tension level. 2. In view of the quality of the machine reel, the uniformity of the caliper profile, i.e. the thickness profile, of the web or a deviation from said profile in a specified way is the most important matter. The second important factor is, as a rule, a uniform moisture profile of the web. The third factor in the order of importance is the tension profile. When the caliper profile and the moisture profile of the web are uniform, the moisture profile is, as a rule, passed on to the tension profile of the roll produced in the slitter- winder. 3. Unevenness and above all obliqueness in the tension profile of the slitter roll cause various disturbances of deformation depending on the paper grade produced. For example, in sack paper of low modulus of elasticity and high stretch at break, an oblique tension profile results in convex/concave-headedness of the rolls, which has been established experimentally. Slack web portions have a detrimental effect on the runnability of the slitter, because slackness cannot be permitted at the blade. 4. In newspaper printing shops, it has been noticed that an uneven tension profile causes, e.g., wrinkles and faults of alignment of colours. If the properties of a roll change to a great extent on exchange of roll, a break in connection with the roll exchange is more probable. According to experience obtained, in sack factories, such a fault in tension profile has occurred as is seen as unevenness of a solidified stretch (a paper that has been cut into sheets does not form a plane face in the non- tensioned state), which is particularly harmful in the making of the sack bottom. 5. Since the tension of the web during drying affects its strength properties, such as tensile stiffness, tensile energy absorption, elongation, and equivalent, an uneven tension profile results in non-homogeneous strength properties in the profile of the web in the cross direction. The problems and the requirements of further development that have occurred in the prior art described above and in corresponding prior art have contributed to making the present invention motivated. The control of various transverse profiles of a web is made particularly problematic by the fact that all profiles act upon other profiles. In respect of the complex nature of this matter, reference is made to the applicant's FI Patent No. 81,848, which is equivalent to EP No. 0408 894 A2, which publications describe the interdependence and control of the grammage and fibre-orientation profiles of paper. Thus, the object of the present invention is to provide a novel method for overall control of the tension profile of the paper web that is produced for the different stages of the papermaking and/or finishing process so that a sufficiently uniform transverse tension profile of the web can be obtained in view of achieving the objectives stated above. In view of achieving the objectives stated above and those that will come out later, the invention is mainly characterized in that, in view of optimizing the quality of the web to be produced, the reel formation, and the runnability of the machine, in the method, the transverse tension profile of the web to be manufactured and/or treated is measured, and that, based on the measurement of said tension profile, set profiles are formed, by whose means one or several actuators of the profile regulation are controlled. In the invention, in the control of the tension profile of the web, such as a paper web, the actuators provided for the regulation of the transverse profiles of the web in the paper machine are utilized. The control may be based either on direct response of the actuators to the tension profile and/or on an indirect effect by the intermediate of other profiles. In the control, it is possible to utilize the relationship of one or several actuators and/or of one or several transverse profiles of the web to the tension profile of the web. In the control in accordance with the present invention of the tension profile of a web, such as a paper web, the interactions between the direct responses of different actuators and different profiles are preferably produced as a model based on response runs carried out by means of the paper machine and/or finishing machine and/or other, equivalent machines for the manufacture and/or treatment of the web material, said machines constituting the object of application of the invention. Between the transverse profiles controlled by the different actuators mentioned above primarily and the tension profile of the web, the following trends are present: there is a positive trend with regard to the grammage profile and to the thickness profile, and there is a negative trend with respect to the moisture profile. Since, in the application of the present invention, it is, as a rule, not favourable to use any existing profile-regulation actuator for the regulation of tension alone, in the control the effects of the operations of regulation required by the control of the tension profile on the other profiles are also taken into account. As regards the theory of regulation, the method in accordance with the invention for the control of the tension profile of a paper web is based on multiple-criteria optimization, by whose means compromises are sought between the variations of the different profile quantities. The principles of control and the related algorithms are known from the prior art, e.g. , from the following cited papers: - Mustonen, H., Koskinen K. , Ritala R., Valtonen E. : Poikkisuunnan laatu- vaihteluiden kokonaishallinta. KCL:n seloste 2063, (Overall control of cross direction quality variations, KCL report 2063) 1993. Mustonen H., Ritala R. : "Coordination of Cross Direction Controls", Proceedings of Control Systems '92 Conference, pages 217...271, 1992. Thus, the subject of the present invention is not simultaneous regulation of a number of profiles as a general method, but the subject is an overall application of methods that are known in themselves to the control of the tension profile. In preliminary process tests that have been carried out, it has been noticed that the tension profile can be affected at least by means of the following actuators: spindles for regulation of the slice profile of the headbox, adjustable-crown rolls in the press, steam box and induction heaters in a calender and equivalent air-blow devices, and web moistening devices. When these actuators are employed, at the same time, consideration must be given to the effects of the controls to the moisture, grammage, thickness and fibre-orientation profiles of the paper web. Even though, in a preferred embodiment of the invention, the tension profile of the web is measured at the vicinity of the reel-up, a uniform tension profile at this location is a reasonably reliable guarantee to the effect that the tension was already uniform in the area where said strength properties of the web were determined, i.e. at a dry solids content of the web equal to 65...85 %. In the following, the invention will be described in detail with reference to different exemplifying embodiments and typical environments of application of the invention illustrated in the schematic figures in the accompanying drawing, the invention being, however, by no means strictly confined to said embodiments or environments. Figure 1 illustrates the main principle of the system of control of the tension profile of a paper web that is being manufactured by means of a paper machine and/or a finishing machine and the connection of said system of control with the prior-art existing systems of regulation of the paper machine and the hierarchal relationship between said systems. Figure 2 illustrates a system in accordance with the invention for the control of the tension profile of a paper web as applied to a paper machine. Figure 3 illustrates a system in accordance with the invention for the control of the tension profile of a paper web as applied in a paper machine and in connection with an on-machine coating device placed in connection with the paper machine. Figure 4 illustrates the method in accordance with the invention as applied in connection with an off-machine coating device of a paper machine. Figure 5 illustrates the method in accordance with the invention as applied in connection with a machine calender or equivalent of a paper machine when the calender alone is used as an actuator. Fig. 1 is a graph illustrating the general principle of the system of control of the transverse tension profile tp of a paper web that is being manufactured by means of a paper machine. In this system, a hierarchal model of regulation is used, in whose upper level the tension-profile control system TS controls the other profile regulation stations 12,13 and 14 of the web by means of the set profiles s 2 ,s 3 and s . The data communication between the upper and lower levels TS and CS takes place along the buses B 2 ,B 3 and B in two directions, because the system TS of the upper level receives the web profile measurement signals m 2 ,πi3 and m 4 from the other systems CS of profile regulation. The web tension measurement signal mi arrives in the system TS directly from the tension measurement devices 11 belonging to the tension profile control unit 10. The lower-level CS regulation systems 12,13 and 14 in Fig. 1 operate in the same way as in the prior-art regulation systems of a paper machine, i.e. each of them attempts to reach its own target profile. It is a difference in comparison to the prior- art operation that the target profiles are determined by the upper-level system TS by means of the set profiles s 2 ,s 3 and s , in connection with whose determination the upper-level system TS also takes into account the interdependence of the different profiles and above all the effects of the different profiles on the tension profile of the web. If some of the actuators for the profile regulation in accordance with the invention are controlled without a particular profile regulation, said actuators can also be controlled directly from the upper-level TS system shown in Fig. 1, as an example of which controls should be mentioned the control of a steam box when it is not used directly for regulating the moisture profile of the web on the basis of a moisture measurement. In such a case, of course, no moisture set profile is determined for the control system of the steam box, but the set values are determined directly for the zones in the steam box. Fig. 2 shows a paper machine as an environment of application of the invention, with which paper machine a machine calender with its parts is integrated, together with a related system in accordance with the invention for the control of the trans¬ verse profiles of the paper web W to be produced. It should also be emphasized in this connection that the environment of application of the invention is by no means confined to the paper machine shown in Fig. 2 alone, said paper machine being shown just for the sake of example. In the paper machine shown in Fig. 2, there is a former section 21, into whose forming gap the headbox 20 feeds a pulp suspension jet. From the carrying wire of the former section 21 the web W is transferred onto the pick-up fabric, on which it is carried into the press section 22, a steam box 54 being fitted on the suction sector of the suction roll 22a placed in connection with the first and the second nip in said press section. In the press section, there is a separate press nip 22b, after which the web W is transferred into the multi-cylinder dryer 23 of the paper machine, which dryer consists of a number of successive cylinder and wire groups. After the dryer section, the paper web W is passed to the machine calender, which consists of two successive soft calenders 31a and 31b, in which, in connection with one of the calender rolls, there are induction heaters 47a and 47b as web W profiling devices, by means of which heaters, in a way in itself known, the transverse profiles of the linear loads in the calendering nips are controlled. After the calenders, the web W is transferred through a web tension measurement station 50 to the reel-up 33, for example a Pope-type reel-up, in which the machine reels R are formed. The devices for measurement of the cross-direction tension profile of the paper web W are known in themselves from the prior art, so that they need not be described in this connection. For the sake of example, regarding these prior-art devices for measure- ment of the profile of web tension, reference is made to the applicant's FI Patent No. 80,522. According to Fig. 2, after the web W tension profile measurement station 50, before the reel-up 33, there is a measurement station 40 for measurement of the grammage profile or dry-weight profile and for measurement of the caliper profile or thickness profile of the web W, from which station the measurement signal m 4 of the thickness profile is passed to the unit 41 for caliper profile cp as well as the measurement signal m 3 of the grammage profile is passed to the unit 42 for cross-direction profile bp of grammage. The unit 42 passes a set- value signal to the regulation unit 43 for the actuators 44 of the slice profile of the headbox 22. From the caliper profile unit 41, a profile signal is passed to the caliper regulation unit 45, to which the input signal cp in for the target profile of the web W is passed. The caliper regulation unit 45 controls the regulation unit 46 for the actuators of the caliper profile, which actuators control the induction heaters or equivalent hot-air blower devices placed in connection with the calender 31a and 31b rolls so that the calenders 31a and 31b accomplish the preset caliper profile of the web W. According to Fig. 2, the station 50 for measurement of the web W tension profile gives its measurement signal mi to the unit 51 for the tension profile tp, which unit again gives a set value s tp to the unit 53 for regulation of the set of feed valves of the steam box 54 in the press section 22. In stead of, or in addition to, the steam box 54 of the press section 22, it is possible to use an adjustable-crown press roll in the press section as an actuator controlled by the web W tension profile tp, by means of which roll the linear load in one or several press nips is affected. In addition to, or along with, the actuators stated above, it is possible to use the means 44 for regulation of the cross-direction profile of the slice of the headbox 20 as actuators, which means 44 of regulation are controlled by the tension-profile tp unit 51, said mode of regulation being illustrated by the interaction line s t drawn with the dashed line in Fig. 2. It is the basic direction of the effect of the regulation of the steam box 54 that the more steam is fed, the dryer and the more tensioned does the web become at the location concerned. In Fig. 2, the caliper profile of the web W has an independent, closed, feed-back connected regulation circuit 40,m ,41,45,46,47a,47b of its own. The grammage profile of the web W also has a closed feed-back connected regulation circuit m 3 ,42, 43,44 of its own. According to Fig. 2, the circuit 51,53,54 for regulation of the transverse moisture profile of the web W obtains its set- value signal, i.e. its target profile, on the basis of the measurement signal π^ of the web W tension profile 10 measured directly before the reel-up 33. A combination of moisture measure¬ ment/tension measurement is also possible in this connection. The paper machine that is shown schematically in Fig. 3 differs from that shown in Fig. 2 in the respect that the web former 21 as shown in Fig. 3 is a so-called hybrid former, in which there is a single-wire initial portion 21a and, after that, a twin-wire forming zone 21b, the press section 22 and the dryer section 23 following after the forming zone being similar to those described in relation to Fig. 2. After the dryer section 23, the web W is passed through an intermediate calender 24, in connection with which there are means for regulation of the cross-direction caliper profile of the web W, such as induction heaters 47 or hot-air blower devices. After the intermedi¬ ate calender 24, the web W is passed through an on-machine coating unit, such as a blade coater or a film-transfer coating device 28a, and through an airborne web dryer 25 to the cylinder group 26, which operates as an intermediate dryer and is provided with twin-wire draw. Before the coating station 28a, there is a station 50 for measurement of the cross-direction tension profile tp of the web W. After the intermediate dryer 26, there follow a second coating station 28b and an airborne web dryer 29, after which the web W is passed to the second intermediate dryer 32 and from there further, through the web W grammage-profile measurement station 40, to the reel-up 33, in which the machine reels R are produced. The system for the control of the cross-direction profiles of the web W shown in Fig. 3 includes a feed-back connected circuit 40,m 4 ,41, 45, 46,47 for regulation of the web W caliper similar to that described in relation to Fig. 2, in which circuit the effective actuator is the hot-air blower device 47 or the induction heater of the intermediate calender 24. Further, the system for the control of the cross-direction profiles of the web W as shown in Fig. 3 includes a feed-back connected loop 40, m 3 , 42, 43, 44 for regulation of the cross-direction profile bp of grammage. In Fig. 3, differing from Fig. 2, the station 50 for measurement of the cross- direction profile of the paper web W tension is not placed directly before the reel- up, but before the first coating station 28a, by means of which arrangement, besides to produce a good machine reel R, attempts are also made to contribute to optimal runnability through the on-machine coating units 28a and 28b and through the related dryer units 25,26,29 and 32 as well as to provide a final product of high quality also in respect of the coating process. In Fig. 3, the measurement signal m j of the cross-direction tension profile tp is passed from the measurement station 50 to the unit 51 and from there further to the tension profile regulation unit 52, to which the tension profile target profile tp in is passed from the set- value unit 55. The target profile tp in need not be fully uniform, but it may be advantageous to make compromises in its respect, and so also in respect of the caliper profile cp and the grammage profile bp, in view of achieving an optimal runnability and an optimal quality of the final product as a whole. From the tension profile regulation unit 52, the regulation signal is passed to the steam box 54 regulation unit 53, which operates in the way described above in relation to Fig. 2. Further, from the tension profile tp regulation unit 52, through the connection st drawn with the dashed line, the grammage profile can be passed to the unit 42. Thus, the measured tension profile tp of the web W can be affected, besides by means of the steam box 54 of the press section 22 and/or by means of the crown adjustment of the press roll, also by means of the headbox slice profiling device 44, and the mutual weight proportions of said modes of regulation can be altered by means of the weighting unit 55,56 described later in relation to Figs. 4 and 5. In stead of, or, preferably, in addition to, the profile regulation actuators described above, if necessary, in the invention it is also possible to apply various web W moistening devices based on supply of water or water vapour, by means of which devices the cross-direction moisture profile of the web W is partly controlled. Also, in the invention, as said web W profiling actuator, it is also possible to use air-blow and pocket- ventilation devices in the dryer section of the paper machine, by means of which devices the supply of drying air is regulated in the cross direction of the web W so as to control the moisture profile of the web in the cross direction. An example of such devices is the moisture profile regulation device 61, such as a water or water- vapour supply box and a system of valves, placed at the beginning of the dryer section 23 in Fig. 2 and controlled by the tension profile tp unit 51. Figs. 4 and 5 illustrate the method in accordance with the invention for the control of the tension profile as applied in connection with the finishing treatment in relation to a paper machine, which finishing may be an on-machine or off-machine process or a paper machine in which there are no other actuators except the thickness actuator of the calender. According to Fig. 4, the paper web W in is brought from the paper machine or paper reel to an intermediate calender 38, in connection with whose calender roll there is a device for regulation of the thickness profile, such as an induction heater 36 or a hot-air blower device. After the calender 38, the web W is passed through the tension profile tp measurement station 50 to the coating station 39. After this, there may be an airborne web dryer or equivalent and possibly a second coating station. Before the reel-up 37, there is a station 36 for measurement of the caliper of the coated web W, from which station 36 the measurement signal m 4 is passed to the caliper profiling unit 51, which gives a regulation signal s cp to the weight selection unit 55. To this unit 55, the regulation signal s tp is also brought from the web tension profile tp measurement unit 41. By means of the weight selection unit 55, the weight proportions of the regulation signals s t and s cp can be regulated so that, if the weight value of one signal is x • 100 , the weight value of the other signal is (1-x) • 100 %. The regulation signal s tc that was created in the unit 55 is passed to the coating-runnability regulation unit 59, to which the target profile is passed from the set- value unit 55. The unit 59 controls the caliper-profile actuator regula¬ tion unit 58, which gives the regulation signal to the actuator 36 of the calender 38. By means of the weight selection unit 55, a contribution can be made, with different paper grades, to an optimal quality and an optimal reel formation as well as to an optimal runnability of the web W through the coating process. Fig. 5 is a general illustration of all processes in which, before the reel-up, there is a calender: on-line machine calender + reel-up, on-line soft calender + reel-up, off-line soft calender, supercalender. Such a combination is present in almost all paper machines, on-line coating machines, off-line coating machines and, of course, in off-line calenders. Fig. 5 illustrates in particular an application of the invention to off-machine finish¬ ing, in which the paper web W in is brought from a machine reel to a supercalender 35, in connection with which there is a web W caliper profile regulation device 36. From the calender 35 the web W is passed through the tension profile tp measure¬ ment station 50 and through the caliper profile measurement station 36 to the reel-up 37, where the reel R is formed. The caliper profile unit 41 and the tension profile unit 51 give the regulation signals s tp and s cp to the weight selection unit 55, which again gives the regulation signal s tc to the reel build regulation unit 57. This unit receives the target profile from the set value unit 55. The unit 57 regulates the device 36 for the regulation of the control of the caliper profile at the supercalender 35 by means of the actuator regulation unit 58. By means of the weight selection unit 55, it is possible to optimize the reeling and the reel R quality as well as the runnability of the process. In the control of the cross-direction tension profile of the web W, the interactions between the direct responses of said actuators and the different profiles are produced as a model based on response runs carried out in a paper machine. In the control of the cross-direction tension profile of the web W, multiple-criteria optimization is applied, by whose means a compromise is sought between the variations of different profile quantities while making use of regulation algorithms in themselves known. The model is located in the tension profile control system TS. In multiple-criteria optimization, the penalty function J tot = ∑ j λ j J j is minimized, wherein is the weight factor of the profile i, and Σ^ = 1. (Steuer, R.E. : Multiple Criteria Optimization: Theory and Applications, John Wiley & Sons Inc. , 1986). J j is the variance i of the penalty function, typically the difference between the measured profile and the set profile, related to the regulation of the profile i, J j = ( ■ measurement " λ i set-' • The interactions between the profiles and the responses of the regulation actuators are illustrated by means of models, by whose means it is possible to calculate the change produced by a change of the setting of a certain actuator or by a change of a certain profile in a certain profile, for example the model AJ: between the actuator U j and the profile X:: OX; A ij = δU; in which case the response of a regulation change ΔUJ on the profile x: can be calculated: Δx: = AJJΔUJ. In the simplest case, A j ; is a linear operator (coefficient or response matrix). In the following, the patent claims will be given, and the various details of the invention may show variation within the scope of the inventive idea defined in said claims and differ from what has been stated above by way of example only.

Claims: Claims 1. A method for the control of the transverse profiles of a web (W) manufactured by means of a machine for the manufacture of a web material, such as a board or paper machine, and/or treated by means of a finishing machine, in which method the transverse caliper and grammage profiles (cp,bp) and/or the moisture profile of the web (W) is/are measured, the actuators (44,54,47,47a,47b) acting upon said profiles being regulated by means of the signals (m 3 ,m ) of measurement of said profiles, characterized in that, in view of optimizing the quality of the web (W) to be produced, the reel formation, and the runnability of the machine, in the method, the transverse tension profile (tp) of the web (W) to be manufactured and/or treated is measured, and that, based on the measurement of said tension profile (tp), set profiles (s 2 ,s 3 ,s 4 ) are formed, by whose means one or several actuators (12,13,14; 36,44,54,61) of the profile regulation are controlled. 2. A method as claimed in claim 1, characterized in that, in the method, a hierarchal regulation model is applied, whose upper-level tension-profile control system (TS) controls the other profile-regulation stations (12,13,14) by means of set profiles (s 2 ,s 3 ,s ), and that over the gaps in the regulation hierarchy, buses (B 2 ,B 3 , B 4 ) are provided, between which a two-way communication is performed so that the upper-level system (TS) receives the profile measurement signals (m 2 ,m 3 ,m 4 ) from the other systems (CS) of profile regulation, and that the measurement signal (rn j ) of tension profile comes directly from the tension measurement device (11) of the web (W) to be produced and/or treated. 3. A method as claimed in claim 1 or 2, characterized in that, in the control of the tension profile (tp) of the web (W) to be manufactured and/or treated, profile regulation actuators (44,54) in themselves known of a paper machine are utilized, such as headbox slice profiling means (44), a steam box (54) placed in connection with a press roll, press-roll or calender-roll crown variation means, induction heaters (36,47,47a,47b) or hot-air blower means of a calender (24,31a, 31b,35,38), and/or means for regulation of the transverse moisture profile of the web (W), such as water or water- vapour supply means or air blower means. 4. A method as claimed in any of the claims 1 to 3, characterized in that, in the control of the transverse tension profile of the web (W), the interactions between the direct responses of said actuators and the different profiles are produced as a model based on response runs carried out in a paper machine. 5. A method as claimed in any of the claims 1 to 4, characterized in that, in the control of the transverse tension profile of the web (W), multiple-criteria optimizing is applied, in which a compromise is sought between the variations of different profile quantities by making use of regulation algorithms known per se. 6. A method as claimed in any of the claims 1 to 5, characterized in that, in the method, the transverse tension profile (tp) of the paper web (W) produced by means of a paper machine is measured after the dryer section (23) of the paper machine substantially directly before the machine reel-up (33) by means of a measurement station (50), the measurement signal (mi) obtained from said station being passed to the tension-profile measurement unit (51), which passes a regulation signal (s tp ) to the unit (53) for regulation of the set of steam valves at the steam box (54) placed in connection with a press roll, preferably a press-suction roll (22a), in the press section (22) of the paper machine (Fig. 2). 7. A method as claimed in claim 6, characterized in that, from said tension profile measurement unit (51), the regulation signal (tp) is passed, as appropriately weighted if necessary, together with the regulation signal (s tp ) that controls the unit (53) for regulation of the steam box (54), to the unit (43) for regulation of the actuator (44) for the slice profile of the headbox (20) (Fig. 2). 8. A method as claimed in any of the claims 1 to 5, characterized in that, in the method, the transverse tension profile (tp) of the web (W) is measured after the dryer section (23) by means of a measurement station (50) placed before any coating station (28a) or any combination or coating stations, and that said measurement signal (m,) is passed to the web tension profile unit (51), from which a regulation signal (s tp ) is passed to the tension profile regulation unit (52), to which, additional¬ ly, the tension target profile (tp irι ) is passed from the set value unit (55), and that, from said tension profile regulation unit (52), a regulation signal is passed to the unit (53) for regulation of the steam box (54) of the press roll (22a) in the press section and/or to the zone regulation means which control the crown adjustment of the press roll in the press section (22) (Fig. 3). 9. A method in an on-line or off-line paper finishing device for the control of the transverse tension profile (tp) in view of optimizing the reel formation of the paper reel (R) to be produced, the quality properties of the product to be manufactured, and the runnability of the finishing process, in which method, by means of the thickness profile measurement device (36) placed before the reel-up (37), the thickness profile (cp) of the treated web is measured, by means of which the reel build regulation unit (57) and/or the coating-runnability regulation unit (59) is/are controlled, characterized in that, in the method, before the thickness profile measurement station (36), the transverse tension profile (tp) of the web (W) is measured, by means of which the web (W) caliper profile regulation device (36) is controlled, which device is preferably an actuator (36) that acts upon the nip pressure in the calendering nip in an off-machine or on-machine calender (35,38), such as an induction heater or a hot-air blower device. 10. A method as claimed in claim 9, characterized in that, in the method, the regulation signals (s tp ,s cp ) received from the web (W) tension measurement unit (41) and from the thickness profile measurement unit (51) are passed to the weight and/or weight selection unit (55), the reel build regulation unit (57) and/or the coating- runnability regulation unit /(59) being controlled by means of the regulation signal (s tc ) received from said unit (55), by means of which said units (57,59) the unit (58) for regulation of the web (W) thickness profile actuators is controlled (Figs. 4 and 5).

Inventors: ELLILAE MARKKU, KOSKIMIES JOUNI, MUSTONEN HARRI, VIRTANEN JORMA, ELLILAE, MARKKU, KOSKIMIES, JOUNI, MUSTONEN, HARRI, VIRTANEN, JORMA
Applicants: VALMET CORP, VALMET CORPORATION
Application year: 1995
Main classification: D21F7
IPC codes: D21F1, D21F7, D21G9