WO1996019615A1 - Process and device for detecting and influencing transversally given properties of paper webs - Google Patents
Process and device for detecting and influencing transversally given properties of paper webs Download PDFInfo
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- WO1996019615A1 WO1996019615A1 PCT/DE1995/001791 DE9501791W WO9619615A1 WO 1996019615 A1 WO1996019615 A1 WO 1996019615A1 DE 9501791 W DE9501791 W DE 9501791W WO 9619615 A1 WO9619615 A1 WO 9619615A1
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- fiber orientation
- paper
- paper web
- formation
- influencing
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- 238000000034 method Methods 0.000 title claims description 16
- 230000008569 process Effects 0.000 title description 2
- 239000000835 fiber Substances 0.000 claims abstract description 52
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 15
- 238000005259 measurement Methods 0.000 claims description 13
- 238000013507 mapping Methods 0.000 claims description 7
- 230000003287 optical effect Effects 0.000 claims description 4
- 238000003909 pattern recognition Methods 0.000 claims description 4
- 238000013528 artificial neural network Methods 0.000 claims description 2
- 230000001276 controlling effect Effects 0.000 claims description 2
- 230000001105 regulatory effect Effects 0.000 claims description 2
- 238000004132 cross linking Methods 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- 229920001131 Pulp (paper) Polymers 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 230000015654 memory Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000009828 non-uniform distribution Methods 0.000 description 1
- 238000012567 pattern recognition method Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
- D21G9/00—Other accessories for paper-making machines
- D21G9/0009—Paper-making control systems
- D21G9/0027—Paper-making control systems controlling the forming section
Definitions
- the invention relates to a method for detecting and influencing the cross profiles of certain properties of paper webs, such as in particular fiber orientation or formation, opacity, basis weight and / or shrinkage.
- the invention also relates to the associated arrangement for carrying out this method for use in paper machines.
- the uniformity of the paper properties across the production direction is decisive for the quality of paper.
- the location-dependent profiles of the paper properties transversely to the direction of production are called cross profiles.
- the monitoring and regulation of the paper properties require a measurement of these cross profiles.
- the object of the invention is to create further improvements and to provide an associated arrangement.
- the object is achieved in that at least the fiber orientation is continuously quantitatively measured and used to regulate the cross profile of the fiber orientation over the paper web when operating a paper machine becomes. If necessary, in addition to the fiber orientation, formation, opacity, basis weight and / or shrinkage are measured at the same time and their transverse profiles are determined.
- a measuring head traversing the paper web is preferably used, which has an optical camera in addition to specific sensors. Such a camera is in particular a so-called CCD camera.
- a control loop for fiber orientation is used to control the fiber orientation cross profile at the headbox of the paper machine.
- a formation control loop is preferably formed from a so-called formation controller, a unit for mapping the paper web, a control path and a unit with associated sensors.
- FIG. 1 is a top view of a paper web with an associated measuring head for measurement
- FIG. 2 is a side view of the principle of a light transmission measurement with an additional light source
- Figure 3 shows a diagram for defining the fiber orientation
- Paper webs and the relevant measurand and Figure 4 is a block diagram of a formation control loop.
- 1 denotes a paper web with the width b, which moves from the headbox of a paper machine (not shown in detail in the figures) in the x direction as the paper running direction.
- the width b of the paper web 1 can be between 3 and 10 m and in particular be 5 m.
- the speed of the paper web in the x direction is, for example, 1500 m / min.
- a measuring head 10 is located on the paper web 1 at a distance without contact. All sensors for measuring the paper properties are spatially combined in the measuring head 10.
- the measuring head 10 To detect cross profiles of certain properties of the paper web 1, the measuring head 10 is moved back and forth over the finished paper web 1 immediately before winding it up to form a coil. The measuring head 10 thus executes a movement traversing with time t. Because of the relative movement of the paper web 1 in the x-direction, the measuring head 10 covers a total zigzag path on the paper web 1.
- the measuring head 10 usually contains a plurality of sensors known from the prior art, which are not dealt with in detail here.
- An optical camera 11 is specifically added to the sensors already present in the measuring head 10.
- a so-called CCD camera (charge coupled device) with electronic memories is advantageously used as the optical camera.
- the camera 11 designed in this way enables simultaneous but independent measurement of the cross profiles of different paper properties, in particular of - fiber orientation
- the properties indicated have the following meaning:
- the fiber orientation is essential for the degree of fiber crosslinking in the paper web. Since the fiber crosslinking determines the strength of the paper web 1, efforts are often made to achieve good fiber crosslinking on the one hand and a uniform one on the other hand. In certain cases, one would also like to give the fiber orientation a preferred direction in order to achieve certain mechanical properties. For this purpose, the fiber orientation must be recorded and influenced locally in detail on the paper web 1.
- a usable measurement of the fiber orientation is achieved on the basis of a camera recording. This results in an image at the respective measuring point.
- the fiber orientation can be measured quantitatively by a suitable evaluation and, for example, an anisotropy factor can be defined.
- FIG. 3 shows a measurement result for a paper web with a medium fiber orientation.
- the angle of the fiber orientation is plotted on the abscissa and the relative frequency is plotted on the ordinate.
- the angle of 90 ° points in the running direction of the machine (MR), the angles 0 and 180 ° point in the relevant transverse direction (QR) so perpendicular to it.
- the anisotropy factor is the ratio of the frequency in the machine direction MR to the frequency in the transverse direction QR. If the fiber orientation is the same for all angles, an anisotropy factor of 1 results.
- the anisotropy factor is> 1, for example 1.5, which means that there is a preferred direction of the fiber orientation in the running direction of the paper web 1.
- the fiber orientation In order to obtain a signal that can be used for control purposes, the fiber orientation must be measured continuously and quasi-continuously.
- the degree of fiber orientation and / or crosslinking is advantageously determined by a pattern recognition performed locally on the camera recording. Neural networks, for example, are suitable for this.
- Formation is the small-area, non-uniform distribution of the fiber mass in the paper web 1 with local accumulation or thinning. In practice, it can be assessed on the basis of a so-called cloudiness when looking through the paper in front of a brightly illuminated surface. The formation can thus also be detected optically, and there may be a connection with the fiber orientation.
- the translucency of paper is referred to as opacity. It is determined by a light transmission measurement in which the intensity of the light that has passed through the paper is measured. For this measurement, a light source is attached to the camera 11 on the other paper side of the paper web 1. The latter can be seen in detail from FIG. 2 that the measuring head 10 traverses back and forth with the camera 11 and a unit 15 with a light source below the paper web 1 carries out corresponding traversing movements.
- the weight per unit area is the mass per unit area of the paper web 1, this size being specified in g / m 2 .
- the basis weight cross profile can also be translucent
- Paper can also be determined by a light transmission measurement with the camera 11.
- the absolute value of the basis weight is not recorded, but only the mean value-free course of the basis weight cross profile is reproduced on the basis of the fluctuations in brightness.
- the shrinkage inevitably results from paper production: in the drying area of the paper machine, water is removed from the paper pulp by passing the paper web 1 over metal rollers heated with steam. Drying can result in uneven shrinkage of the paper web 1 over its width b. If the actuators for basis weight and fiber orientation are in front of the drying section, the shrinkage undesirably changes the places of action of these actuators.
- Controlling the fiber orientation cross profile on the paper web 1 requires knowledge of the assignment of each actuator to its place of action in the finished paper. This assignment is usually called "mapping".
- the traversing camera 11 can achieve an overall image across the entire width of the paper web 1. In the form of stochastic irregularities on the upper side of the paper web 1, the impression of regular screen markings is included.
- a complete control circuit 3 for fiber orientation consists in detail of a fiber orientation controller 31, a mapping unit 32, an actuator 33, a controlled system 34 and a sensor unit 35. These units are each only schematic (“black boxes”) shown, the signal feedback to the comparison point 30.
- the mapping function of the unit 32 also takes into account the change in the assignment of the actuator 33 to the relevant actuator effect caused by shrinkage. Overall, the possibility of influencing the fiber orientation already suggested in the other context can thus be supplemented by the specified quantitative measurement of the fiber orientation to build up a complete control system. In the same way, the other significant properties of paper webs, such as formation, opacity and basis weight, can be incorporated into the control process, taking shrinkage into account.
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Abstract
Description
Beschreibungdescription
Verfahren zur Erfassung und Beeinflussung der Querprofile bestimmter Eigenschaften von Papierbahnen und zugehörige AnordnungMethod for recording and influencing the cross profiles of certain properties of paper webs and the associated arrangement
Die Erfindung bezieht sich auf ein Verfahren zur Erfassung und Beeinflussung der Querprofile bestimmter Eigenschaften von Papierbahnen, wie insbesondere Faserorientierung bzw. Formation, Opazität, Flächengewicht und/oder Schrumpfung. Daneben bezieht sich die Erfindung auch auf die zugehörige Anordnung zur Durchführung dieses Verfahrens zur Verwendung bei Papiermaschinen.The invention relates to a method for detecting and influencing the cross profiles of certain properties of paper webs, such as in particular fiber orientation or formation, opacity, basis weight and / or shrinkage. In addition, the invention also relates to the associated arrangement for carrying out this method for use in paper machines.
Für die Qualität von Papier ist unter anderem die Gleich¬ mäßigkeit der Papiereigenschaften quer zur Produktionsrich¬ tung maßgeblich. Die ortsabhängigen Verläufe der Papiereigen¬ schaften quer zur Produktionsrichtung werden Querprofile ge¬ nannt. Die Überwachung und Regelung der Papiereigenschaften erfordern eine Messung dieser Querprofile.Among other things, the uniformity of the paper properties across the production direction is decisive for the quality of paper. The location-dependent profiles of the paper properties transversely to the direction of production are called cross profiles. The monitoring and regulation of the paper properties require a measurement of these cross profiles.
Die Messung der Querprofile erfolgt bisher für jede Eigen¬ schaft des Papiers einzeln. Angestrebt wird, die einzelnen Eigenschaften der Papierbahn unabhängig voneinander zu opti- mieren. Gemäß der Veröffentlichung "Das Papier" (1993), Nr.The measurement of the cross profiles has so far been carried out individually for each property of the paper. The aim is to optimize the individual properties of the paper web independently of one another. According to the publication "Das Papier" (1993), no.
10A, S. V150 - V155, sind dafür neuartige Aktoren entwickelt, die eine Beeinflussung zumindest der Querprofileigenschaften von Flächengewicht und Faserorientierung unabhängig vonein¬ ander ermöglichen und unmittelbar am Stoffauflauf eingreifen.10A, p. V150 - V155, new types of actuators have been developed for this purpose, which make it possible to influence at least the cross-profile properties of the basis weight and fiber orientation independently of one another and intervene directly on the headbox.
Aufgabe der Erfindung ist es demgegenüber, weitere Verbesse¬ rungen zu schaffen und eine zugehörige Anordnung anzugeben.In contrast, the object of the invention is to create further improvements and to provide an associated arrangement.
Die Aufgabe ist erfindungsgemäß dadurch gelöst, daß zumindest die Faserorientierung fortlaufend quantitativ gemessen und zur Regelung des Querprofils der Faserorientierung über die Papierbahn beim Betrieb einer Papiermaschine herangezogen wird. Gegebenenfalls werden neben der Faserorientierung gleichzeitig Formation, Opazität, Flächengewicht und/oder Schrumpfung gemessen und deren Querprofile bestimmt. Dazu wird vorzugsweise ein über die Papierbahn traversierender Meßkopf verwendet, der neben spezifischen Sensoren eine optische Kamera aufweist. Eine solche Kamera ist insbesondere eine sogenannte CCD-Kamera.The object is achieved in that at least the fiber orientation is continuously quantitatively measured and used to regulate the cross profile of the fiber orientation over the paper web when operating a paper machine becomes. If necessary, in addition to the fiber orientation, formation, opacity, basis weight and / or shrinkage are measured at the same time and their transverse profiles are determined. For this purpose, a measuring head traversing the paper web is preferably used, which has an optical camera in addition to specific sensors. Such a camera is in particular a so-called CCD camera.
Durch ein geeignetes Auswerteverfahren von fortlaufenden Kameraaufnahmen der Papierbahn mittels Mustererkennungsver¬ fahren od. dgl . wird nunmehr direkt eine insbesondere für die Faserorientierung der Papierbahn signifikante Meßgröße er¬ halten, aus der durch Vergleich mit einem vorgegebenen Soll¬ wertprofil ein Regelsignal ableitbar ist. Damit können im Gegensatz zum angegebenen Stand der Technik komplette Faser- orientierungsquerprofile ausgeregelt werden.By means of a suitable evaluation method of continuous camera recordings of the paper web by means of a pattern recognition method or the like. a measured variable which is significant in particular for the fiber orientation of the paper web is now obtained, from which a control signal can be derived by comparison with a predetermined setpoint value profile. In contrast to the state of the art, complete fiber orientation cross profiles can be adjusted.
Bei der zugehörigen Anordnung wird über den angegebenen Me߬ kopf hinaus insbesondere ein Regelkreis für die Faserorien- tierung zur Regelung des Faserorientierungsquerprofils am Stoffauflauf der Papiermaschine verwendet. Vorzugsweise ist ein solcher Formationsregelkreis aus einem sogenannten For¬ mationsregler, einer Einheit zum sogenannten Mapping der Papierbahn, einer Regelstrecke und einer Einheit mit zuge- höriger Sensorik gebildet.In the associated arrangement, in addition to the specified measuring head, in particular a control loop for fiber orientation is used to control the fiber orientation cross profile at the headbox of the paper machine. Such a formation control loop is preferably formed from a so-called formation controller, a unit for mapping the paper web, a control path and a unit with associated sensors.
Weitere Einzelheiten und Vorteile der Erfindung ergeben sich aus der nachfolgenden Figurenbeschreibung von Ausführungs¬ beispielen anhand der Zeichnung in Verbindung mit den weite- ren Ansprüchen. Es zeigen in jeweils schematischer Darstel¬ lungFurther details and advantages of the invention emerge from the following description of the figures of exemplary embodiments with reference to the drawing in conjunction with the further claims. They each show a schematic representation
Figur 1 die Draufsicht auf eine Papierbahn mit einem zuge¬ hörigen Meßkopf zur Vermessung, Figur 2 in Seitenansicht das Prinzip einer Lichttransmis¬ sionsmessung mit zusätzlicher Lichtquelle, Figur 3 ein Diagramm zur Definition der Faserorientierung bei1 is a top view of a paper web with an associated measuring head for measurement, FIG. 2 is a side view of the principle of a light transmission measurement with an additional light source, Figure 3 shows a diagram for defining the fiber orientation
Papierbahnen sowie der diesbezüglichen Meßgröße und Figur 4 ein Blockschaltbild eines Formationsregelkreises.Paper webs and the relevant measurand and Figure 4 is a block diagram of a formation control loop.
Die Figuren werden teilweise gemeinsam beschrieben.Some of the figures are described together.
In Figur 1 und Figur 2 kennzeichnet 1 eine Papierbahn mit der Breite b, welche sich vom Stoffauflauf einer in den Figuren nicht im einzelnen dargestellten Papiermaschine in x-Richtung als Papierlaufrichtung bewegt. Die Breite b der Papierbahn 1 kann zwischen 3 und 10 m liegen und insbesondere 5 m betra¬ gen. Die Geschwindigkeit der Papierbahn in x-Richtung beträgt beispielsweise 1500 m/min. Auf der Papierbahn 1 befindet sich berührungslos im Abstand ein Meßkopf 10. In dem Meßkopf 10 sind alle Sensoren zur Messung der Papiereigenschaften räum¬ lich zusammengefaßt.In FIG. 1 and FIG. 2, 1 denotes a paper web with the width b, which moves from the headbox of a paper machine (not shown in detail in the figures) in the x direction as the paper running direction. The width b of the paper web 1 can be between 3 and 10 m and in particular be 5 m. The speed of the paper web in the x direction is, for example, 1500 m / min. A measuring head 10 is located on the paper web 1 at a distance without contact. All sensors for measuring the paper properties are spatially combined in the measuring head 10.
Zur Erfassung von Querprofilen bestimmter Eigenschaften der Papierbahn 1 wird der Meßkopf 10 über die fertige Papierbahn 1 unmittelbar vor dere Aufwickeln zu einem Coil hin- und herbewegt. Der Meßkopf 10 führt also eine mit der Zeit t traversierende Bewegung aus. Wegen der Relativbewegung der Papierbahn 1 in x-Richtung legt der Meßkopf 10 insgesamt einen zickzackförmigen Weg auf der Papierbahn 1 zurück.To detect cross profiles of certain properties of the paper web 1, the measuring head 10 is moved back and forth over the finished paper web 1 immediately before winding it up to form a coil. The measuring head 10 thus executes a movement traversing with time t. Because of the relative movement of the paper web 1 in the x-direction, the measuring head 10 covers a total zigzag path on the paper web 1.
Üblicherweise beinhaltet der Meßkopf 10 eine Mehrzahl von vom Stand der Technik bekannten Sensoren, auf die hier nicht im einzelnen eingegangen wird. Zu den im Meßkopf 10 bereits vor¬ handenen Sensoren ist speziell eine optische Kamera 11 hin- zugefügt. Als optische Kamera wird vorteilhafterweise eine sogenannte CCD-Kamera (Charge coupled device) mit elektroni¬ schen Speichern verwendet.The measuring head 10 usually contains a plurality of sensors known from the prior art, which are not dealt with in detail here. An optical camera 11 is specifically added to the sensors already present in the measuring head 10. A so-called CCD camera (charge coupled device) with electronic memories is advantageously used as the optical camera.
Durch die so konzipierte Kamera 11 ist die gleichzeitige, aber voneinander unabhängige Messung der Querprofile von verschiedenen Papiereigenschaften möglich und zwar insbe¬ sondere von - FaserorientierungThe camera 11 designed in this way enables simultaneous but independent measurement of the cross profiles of different paper properties, in particular of - fiber orientation
- Formation- formation
- Opazität und Flächengewicht- opacity and basis weight
- Schrumpfung.- shrinkage.
Im einzelnen haben die angegebenen Eigenschaften folgende Be¬ deutung: Die Faserorientierung ist wesentlich für den Grad der Faservernetzung in der Papierbahn. Da die Faservernetzung die Festigkeit der Papierbahn 1 bestimmt, ist man oft be- strebt, einerseits eine gute und andererseits eine gleich¬ mäßige Faservernetzung zu erreichen. In bestimmten Fällen möchte man der Faserorientierung auch eine Vorzugsrichtung geben, um so bestimmte mechanische Eigenschaften zu erzielen. Dazu muß die Faserorientierung im einzelnen lokal auf der Papierbahn 1 erfaßt und beeinflußt werden.The properties indicated have the following meaning: The fiber orientation is essential for the degree of fiber crosslinking in the paper web. Since the fiber crosslinking determines the strength of the paper web 1, efforts are often made to achieve good fiber crosslinking on the one hand and a uniform one on the other hand. In certain cases, one would also like to give the fiber orientation a preferred direction in order to achieve certain mechanical properties. For this purpose, the fiber orientation must be recorded and influenced locally in detail on the paper web 1.
Mit einer Anordnung gemäß den Figuren 1 und 2 wird eine ver¬ wertbare Messung der Faserorientierung anhand einer Kamera¬ aufnahme erreicht. Damit ergibt sich ein Bild an der jewei- ligen Meßstelle. Durch eine geeignete Auswertung läßt sich die Faserorientierung quantitativ messen und beispielsweise ein Anisotropiefaktor definieren.With an arrangement according to FIGS. 1 and 2, a usable measurement of the fiber orientation is achieved on the basis of a camera recording. This results in an image at the respective measuring point. The fiber orientation can be measured quantitatively by a suitable evaluation and, for example, an anisotropy factor can be defined.
In Figur 3 ist ein Meßergebnis für eine Papierbahn mit mittlerer Faserorientierung dargestellt. Dabei ist auf der Abszisse der Winkel der Faserorientierung und auf der Ordinate die relative Häufigkeit aufgetragen. Der Winkel von 90° zeigt hierbei in Laufrichtung der Maschine (MR) , die Winkel 0 und 180° zeigen in die diesbezügliche Querrichtung (QR) also senkrecht dazu. Der Anisotropiefaktor ergibt sich als Verhältnis der Häufigkeit in Maschinenrichtung MR zur Häufigkeit in Querrichtung QR. Ist die Faserorientierung für alle Winkel gleich, ergibt sich ein Anisotropiefaktor von 1. Im Beispiel der Figur 3 liegt der Anisotropiefaktor > 1, bei- spielsweise 1,5, was bedeutet, daß eine Vorzugsrichtung der Faserorientierung in Laufrichtung der Papierbahn 1 besteht. Um ein für Regelzwecke verwertbares Signal zu erhalten, muß der Faserorientierung fortlaufend und quasi-kontinuierlich gemessen werden. In vorteilhafter Weise wird der Grad der Faserorientierung und/oder -Vernetzung durch eine an der Kameraaufnahme lokal durchgeführte Mustererkennung bestimmt. Dafür eignen sich beispielsweise neuronale Netze.FIG. 3 shows a measurement result for a paper web with a medium fiber orientation. The angle of the fiber orientation is plotted on the abscissa and the relative frequency is plotted on the ordinate. The angle of 90 ° points in the running direction of the machine (MR), the angles 0 and 180 ° point in the relevant transverse direction (QR) so perpendicular to it. The anisotropy factor is the ratio of the frequency in the machine direction MR to the frequency in the transverse direction QR. If the fiber orientation is the same for all angles, an anisotropy factor of 1 results. In the example in FIG. 3, the anisotropy factor is> 1, for example 1.5, which means that there is a preferred direction of the fiber orientation in the running direction of the paper web 1. In order to obtain a signal that can be used for control purposes, the fiber orientation must be measured continuously and quasi-continuously. The degree of fiber orientation and / or crosslinking is advantageously determined by a pattern recognition performed locally on the camera recording. Neural networks, for example, are suitable for this.
Als Formation wird dagegen die kleinflächige uneinheitliche Verteilung der Fasermasse in der Papierbahn 1 mit stellen- weise Anhäufung bzw. Verdünnung bezeichnet. In der Praxis kann sie aufgrund einer sog. Wolkigkeit bei der Durchsicht des Papiers vor einer hell leuchtenden Fläche beurteilt wer¬ den. Die Formation kann also ebenfalls optisch erfaßt werden, wobei ein Zusammenhang mit der Faserorientierung bestehen kann.Formation, on the other hand, is the small-area, non-uniform distribution of the fiber mass in the paper web 1 with local accumulation or thinning. In practice, it can be assessed on the basis of a so-called cloudiness when looking through the paper in front of a brightly illuminated surface. The formation can thus also be detected optically, and there may be a connection with the fiber orientation.
Als Opazität wird die Durchscheinbarkeit von Papier bezeich¬ net. Sie wird durch eine Lichttransmissionsmessung bestimmt, bei der die Intensität des durch das Papier hindurchgedrunge- nen Lichtes gemessen wird. Für diese Messung wird gegenüber der Kamera 11 auf der anderen Papierseite der Papierbahn 1 eine Lichtquelle angebracht. Letzteres ist im einzelnen aus Figur 2 ersichtlich, daß der Meßkopf 10 mit der Kamera 11 hin- und hertraversiert und eine Einheit 15 mit einer Licht- quelle unterhalb der Papierbahn 1 entsprechende traversierende Bewegungen ausführt.The translucency of paper is referred to as opacity. It is determined by a light transmission measurement in which the intensity of the light that has passed through the paper is measured. For this measurement, a light source is attached to the camera 11 on the other paper side of the paper web 1. The latter can be seen in detail from FIG. 2 that the measuring head 10 traverses back and forth with the camera 11 and a unit 15 with a light source below the paper web 1 carries out corresponding traversing movements.
Als Flächengewicht bezeichnet man die flächenbezogene Masse der Papierbahn 1, wobei diese Größe in g/m2 angegeben wird. Auch das Flächengewichtsquerprofil kann bei durchscheinendemThe weight per unit area is the mass per unit area of the paper web 1, this size being specified in g / m 2 . The basis weight cross profile can also be translucent
Papier ebenfalls durch eine Lichttransmissionsmessung mit der Kamera 11 bestimmt werden. Üblicherweise wird nicht der Abso¬ lutwert des Flächengewichtes erfaßt, sondern nur der ittel- wertfreie Verlauf des Flächengewichtsquerprofils anhand der Helligkeitsschwankungen wiedergegeben. Die Schrumpfung ergibt sich zwangsläufig bei der Papierher¬ stellung: Im Trocknungsbereich der Papiermaschine wird der Papiermasse Wasser entzogen, indem die Papierbahn 1 über mit Dampf beheizte Metallwalzen geführt wird. Durch die Trocknung kann sich eine ungleichmäßige Schrumpfung der Papierbahn 1 über seine Breite b ergeben. Wenn sich die Stellglieder für Flächengewicht und Faserorientierung vor der Trocknungspartie befinden, verändert die Schrumpfung unerwünschterweise die Wirkungsorte dieser Stellglieder.Paper can also be determined by a light transmission measurement with the camera 11. Usually the absolute value of the basis weight is not recorded, but only the mean value-free course of the basis weight cross profile is reproduced on the basis of the fluctuations in brightness. The shrinkage inevitably results from paper production: in the drying area of the paper machine, water is removed from the paper pulp by passing the paper web 1 over metal rollers heated with steam. Drying can result in uneven shrinkage of the paper web 1 over its width b. If the actuators for basis weight and fiber orientation are in front of the drying section, the shrinkage undesirably changes the places of action of these actuators.
Eine Regelung des Faserorientierungsquerprofils an der Papierbahn 1 erfordert die Kenntnis über die Zuordnung jedes Stellgliedes zu seinem Wirkungsort im fertigen Papier. Diese Zuordnung wird üblicherweise "Mapping" genannt. Durch die traversierende Kamera 11 kann insgesamt ein Bild über die gesamte Breite der Papierbahn 1 erzielt werden. In stocha- stischen Unregelmäßigkeiten auf der Oberseite der Papierbahn 1 ist der Abdruck von regelmäßigen Siebmarkierungen ent¬ halten.Controlling the fiber orientation cross profile on the paper web 1 requires knowledge of the assignment of each actuator to its place of action in the finished paper. This assignment is usually called "mapping". The traversing camera 11 can achieve an overall image across the entire width of the paper web 1. In the form of stochastic irregularities on the upper side of the paper web 1, the impression of regular screen markings is included.
In der Veröffentlichung "Das Papier" (1990), Nr. 10, S. 529 - 537, ist im einzelnen eine Methodik zur Bestimmung des Schrumpfungsquerprofils beschrieben: Eine zweidimensionale schnell Fourier-Transformation (FFT = fast fourier trans- formation) , die auf die Bildpunkte der Papieroberseite ange¬ wendet wird, liefert deutlich die zu den Siebmarkierungen gehörigen Spektrallinien. Eine Rücktransformation dieser Spektrallinien ergibt die unverrauschte Siebstruktur auf der geschrumpften Papierbahn 1. Durch Vergleich mit der bekannten Geometrie der Siebmarkierungen erhält man das Schrumpfungs- querprofil. Das Schrumpfungsprofil kann z.B. dafür verwandt werden, um das Mapping durchzuführen.In the publication "Das Papier" (1990), No. 10, pp. 529-537, a method for determining the cross-sectional shrinkage profile is described in detail: A two-dimensional fast Fourier transformation (FFT = fast fourier transformation) based on If the image points on the top of the paper are used, the spectral lines belonging to the screen markings are clearly provided. A back transformation of these spectral lines results in the noiseless sieve structure on the shrunk paper web 1. By comparison with the known geometry of the sieve markings, the shrinking cross profile is obtained. The shrinkage profile can e.g. used to do the mapping.
Bei bisher verwendeten Stoffauflaufen wird üblicherweise keine unabhängige Regelung von Flächengewichts- und Fase¬ rorientierungsprofil durchgeführt. Man beschränkt sich auf die Regelung des Flächengewichtes als der wichtigeren der beiden Größen. Wegen steigender mechanischer Beanspruchungen beim Verarbeiten und Benutzen von Papier hat sich neuerdings die Forderung sowohl nach einem möglichst gleichmäßigen als auch auf Wunschwerte einstellbaren Faserorientierungsquer- profil verstärkt. Bei den in der eingangs genannten Ver¬ öffentlichung vorhandenen Stellgliedern für die Vorgabe der Faserorientierung wird das Querprofil nicht geregelt, sondern werden die einzelnen Stellglieder ohne direkte Rückkopplung eingestellt. Dafür sind im allgemeinen spezifische Erfah- rungswerte notwendig.In the case of headboxes previously used, no independent regulation of the basis weight and fiber orientation profile is usually carried out. One limits itself to the regulation of the basis weight as the more important one two sizes. Due to increasing mechanical stresses when processing and using paper, the demand for a fiber orientation cross profile that is as uniform as possible and that can be adjusted to desired values has recently increased. In the case of the actuators for specifying the fiber orientation available in the publication mentioned at the beginning, the transverse profile is not regulated, but the individual actuators are set without direct feedback. This generally requires specific experience.
Aufgrund des anhand Figur 1 und Figur 2 im einzelnen be¬ schriebenen Meßkopfes 10 mit Kamera 11 ergibt sich bei ge¬ eignet ausgebildeten Stoffauflaufen die Möglichkeit, die genau ermittelten Querprofile unabhängig voneinander zu beeinflussen und auszuregeln. Nunmehr kann man geeignete Stellglieder zur Vorgabe des Faserorientierungsquerprofils, das entsprechend der Figur 1 und 2 gemessen und online durch Mustererkennung ausgewertet wird, verwenden. Das Vorhanden- sein von Stellgliedern und Sensorik ermöglicht somit denOn the basis of the measuring head 10 with camera 11 described in detail with reference to FIG. 1 and FIG. 2, with suitably designed headboxes there is the possibility of influencing and correcting the precisely determined cross profiles independently of one another. Suitable actuators can now be used for specifying the fiber orientation cross profile, which is measured in accordance with FIGS. 1 and 2 and evaluated online by pattern recognition. The presence of actuators and sensors therefore enables this
Aufbau einer Regelungeinrichtung des diesbezüglichen Quer¬ profils für den praxisgerechten Einsatz bei Papiermaschinen.Setup of a control device of the relevant cross-profile for practical use in paper machines.
In Figur 4 besteht ein kompletter Regelkreis 3 für die Faser- Orientierung im einzelnen aus einem Faserorientierungsregler 31, einer Mapping-Einheit 32, einem Stellglied 33, einer Regelstrecke 34 und einer Sensorikeinheit 35. Diese Einheiten sind jeweils nur schematisch ("black boxes") dargestellt, wobei die Signalrückführung zum Vergleichspunkt 30 erfolgt.In FIG. 4, a complete control circuit 3 for fiber orientation consists in detail of a fiber orientation controller 31, a mapping unit 32, an actuator 33, a controlled system 34 and a sensor unit 35. These units are each only schematic ("black boxes") shown, the signal feedback to the comparison point 30.
Durch die fortlaufende Messung der Faserorientierung ist eine Rückkopplung der ermittelten Querprofilsignale und Aufschal¬ tung auf einen Reglervergleichspunkt 30 möglich. Dabei be¬ rücksichtigt gleichermaßen die Mapping-Funktion der Einheit 32 die durch Schrumpfung verursachte Änderung der Zuordnung von Stellglied 33 zur diesbezüglichen Stellgliedwirkung. Insgesamt kann somit die im anderen Zusammenhang bereits vorgeschlagene Beeinflussungsmöglichkeit der Faserorientie¬ rung durch die angegebene quantitative Messung der Faser¬ orientierung zum Aufbau einer Komplettregelung ergänzt werden. Gleichermaßen können auch die anderen signifikanten Eigenschaften bei Papierbahnen, wie Formation, Opazität und Flächengewicht bei Berücksichtigung der Schrumpfung in den Regelvorgang eingebunden werden. Due to the continuous measurement of the fiber orientation, a feedback of the determined cross-profile signals and connection to a controller comparison point 30 is possible. The mapping function of the unit 32 also takes into account the change in the assignment of the actuator 33 to the relevant actuator effect caused by shrinkage. Overall, the possibility of influencing the fiber orientation already suggested in the other context can thus be supplemented by the specified quantitative measurement of the fiber orientation to build up a complete control system. In the same way, the other significant properties of paper webs, such as formation, opacity and basis weight, can be incorporated into the control process, taking shrinkage into account.
Claims
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI972576A FI972576A7 (en) | 1994-12-19 | 1995-12-14 | Method for collecting data relating to cross-sectional profiles of specified properties of paper webs and for influencing these properties, and apparatus relating to the method |
| DE59505937T DE59505937D1 (en) | 1994-12-19 | 1995-12-14 | METHOD FOR DETECTING AND INFLUENCING THE CROSS-PROFILES OF CERTAIN PROPERTIES OF PAPER FILMS AND RELATED ARRANGEMENT |
| EP95940956A EP0799348B1 (en) | 1994-12-19 | 1995-12-14 | Process and device for detecting and influencing transversally given properties of paper webs |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4445260 | 1994-12-19 | ||
| DEP4445260.8 | 1994-12-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1996019615A1 true WO1996019615A1 (en) | 1996-06-27 |
Family
ID=6536248
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/DE1995/001791 WO1996019615A1 (en) | 1994-12-19 | 1995-12-14 | Process and device for detecting and influencing transversally given properties of paper webs |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0799348B1 (en) |
| AT (1) | ATE180026T1 (en) |
| DE (1) | DE59505937D1 (en) |
| FI (1) | FI972576A7 (en) |
| WO (1) | WO1996019615A1 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998028490A1 (en) * | 1996-12-20 | 1998-07-02 | Siemens Aktiengesellschaft | Method and device for conducting a process in the production of paper |
| EP0826821A3 (en) * | 1996-08-30 | 1999-06-16 | Voith Sulzer Papiermaschinen Gesellschaft mbH | Control device having a plurality of sensors |
| WO1999056112A1 (en) * | 1998-04-23 | 1999-11-04 | Isover Saint-Gobain | Method for determining the orientation of fibre structure in a mineral wool mat |
| GB2342457A (en) * | 1998-10-07 | 2000-04-12 | John Clark | A quality control sampling system with barcode reader and video camera |
| EP0995834A1 (en) * | 1998-09-24 | 2000-04-26 | Voith Sulzer Papiertechnik Patent GmbH | Method and device for improving the cross-machine shrinkage profile in a paper machine |
| WO2003072874A1 (en) * | 2002-02-21 | 2003-09-04 | Abb Ltd. | On-line fiber orientation closed-loop control |
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-
1995
- 1995-12-14 AT AT95940956T patent/ATE180026T1/en active
- 1995-12-14 DE DE59505937T patent/DE59505937D1/en not_active Expired - Lifetime
- 1995-12-14 EP EP95940956A patent/EP0799348B1/en not_active Expired - Lifetime
- 1995-12-14 WO PCT/DE1995/001791 patent/WO1996019615A1/en active IP Right Grant
- 1995-12-14 FI FI972576A patent/FI972576A7/en not_active Application Discontinuation
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| WO1988005099A1 (en) * | 1986-12-30 | 1988-07-14 | Niemi, Ulla, Riitta, Anneli | Method and apparatus for control of dry line on the wire of a fourdrinier paper machine |
| DE3827084C1 (en) * | 1988-08-10 | 1989-11-16 | Sulzer-Escher Wyss Gmbh, 7980 Ravensburg, De | |
| EP0401188A2 (en) * | 1989-06-01 | 1990-12-05 | Valmet Paper Machinery Inc. | Control system for a paper or board machine |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0826821A3 (en) * | 1996-08-30 | 1999-06-16 | Voith Sulzer Papiermaschinen Gesellschaft mbH | Control device having a plurality of sensors |
| US6179964B1 (en) | 1996-08-30 | 2001-01-30 | Voith Sulzer Papiermaschinen Gmbh | Method and control device for paper web profile control with plurality of sensors |
| WO1998028490A1 (en) * | 1996-12-20 | 1998-07-02 | Siemens Aktiengesellschaft | Method and device for conducting a process in the production of paper |
| WO1999056112A1 (en) * | 1998-04-23 | 1999-11-04 | Isover Saint-Gobain | Method for determining the orientation of fibre structure in a mineral wool mat |
| EP0995834A1 (en) * | 1998-09-24 | 2000-04-26 | Voith Sulzer Papiertechnik Patent GmbH | Method and device for improving the cross-machine shrinkage profile in a paper machine |
| US6303001B1 (en) | 1998-09-24 | 2001-10-16 | Voith Sulzer Papiertechnik Patent Gmbh | Process for improving the shrinkage cross direction profile and paper having an improved cross |
| EP1323862A1 (en) * | 1998-09-24 | 2003-07-02 | Voith Paper Patent GmbH | Method for regulating the cross-machine shrinkage profile in a paper machine |
| GB2342457A (en) * | 1998-10-07 | 2000-04-12 | John Clark | A quality control sampling system with barcode reader and video camera |
| WO2003072874A1 (en) * | 2002-02-21 | 2003-09-04 | Abb Ltd. | On-line fiber orientation closed-loop control |
Also Published As
| Publication number | Publication date |
|---|---|
| FI972576L (en) | 1997-06-17 |
| EP0799348B1 (en) | 1999-05-12 |
| ATE180026T1 (en) | 1999-05-15 |
| FI972576A0 (en) | 1997-06-17 |
| DE59505937D1 (en) | 1999-06-17 |
| FI972576A7 (en) | 1997-06-17 |
| EP0799348A1 (en) | 1997-10-08 |
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