EP0366768A1 - Caisse de tete pour machines a papier - Google Patents

Caisse de tete pour machines a papier

Info

Publication number
EP0366768A1
EP0366768A1 EP19890905581 EP89905581A EP0366768A1 EP 0366768 A1 EP0366768 A1 EP 0366768A1 EP 19890905581 EP19890905581 EP 19890905581 EP 89905581 A EP89905581 A EP 89905581A EP 0366768 A1 EP0366768 A1 EP 0366768A1
Authority
EP
European Patent Office
Prior art keywords
headbox
flow
zone
headbox according
pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19890905581
Other languages
German (de)
English (en)
Inventor
Hans Peter Arledter
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JM Voith AG
Original Assignee
JM Voith AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by JM Voith AG filed Critical JM Voith AG
Publication of EP0366768A1 publication Critical patent/EP0366768A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/02—Head boxes of Fourdrinier machines
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/02—Head boxes of Fourdrinier machines
    • D21F1/026—Details of the turbulence section
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/06—Regulating pulp flow

Definitions

  • the invention relates to a headbox for paper machines with at least one tube bundle formed from flow tubes in the flow channel between the distributor tube to be fed and the outlet nozzle.
  • the headbox of a paper machine has the task of distributing the StuffSuspension machine-wide and placing it on the running sieve.
  • the uniformity with regard to speed, thickness and direction of the material jet across the width of the paper machine is decisive for the quality of the paper web.
  • the level of numerous quality features of the paper required for further processing depends on the ratio of the material jet speed to the screen speed (outlet ratio) and on the speed profile (transverse direction) in the flow channel between the distribution pipe and the outlet nozzle. These are primarily the fiber orientation, the distribution of the strength potential of the paper between the machine's longitudinal and transverse directions, the formation, the specific volume and the porosity.
  • a speed difference between jet and sieve of only 2% can, for example, lead to a change in the tear length ratio (RL ⁇ / RL) from 1.9 to 2.7.
  • speed differences of the jet across the width of more than 3% are not uncommon.
  • the defined curl (based on the machine axis) is an important requirement for papers for high-speed copiers and continuous printers.
  • One requirement of the producers of fluting and kraftliner is the uniform distribution of strength in the connection plane of the layers, ie the preferred fiber orientation of the rubberized surfaces is one of the decisive factors for the strength of the bond between the layers.
  • the fiber orientation influences the strength vector in the plane far more than the strength vector out of the plane.
  • Such relationships between fiber orientation and problems in further processing have long been known.
  • the targeted fight fails so far, however, on the complex measurement of the main fiber direction.
  • the main fiber direction is determined by measuring the tear length.
  • the tear length must be determined in three directions.
  • two tear lengths are preferably used, which are directed at an angle of 30 ° to the driver side and the drive side.
  • the angle of the main axis of the tear length ellipse to the machine running direction is then obtained.
  • This method is very complex. The measurement effort is reduced if one is satisfied with the relative tearing length difference of the strips inclined at 60 ° to one another and thus dispenses with the absolute value of the angular deviation.
  • the measurement outlay is still very large for process engineering use.
  • the simplest way to determine the fiber orientation is a recently developed optical measuring method, which can also be used in on-line operation.
  • This optical measuring method opens up new possibilities for headbox cross-profile control with respect to basis weight and fiber orientation, since the measuring data of this method can be used directly to control the paper machine.
  • deviations in the area-related mass in the cross-machine direction are carried out by finely adjusting the lip opening of the material outlet nozzle.
  • a diaphragm protruding into the material flow is displaced by a large number of adjusting spindles, as a result of which a good basis weight cross section should be achieved.
  • the inadequacy of this method is that the parameters required to achieve an optimal basis weight profile suitable aperture position does not necessarily coincide with an optimal fiber orientation profile. To avoid angular deviations of the main fiber direction from the machine running direction, there are substantially higher requirements for the headbox than to avoid sheet weight deviations.
  • the distributor contour of the distributor pipe can be calculated using the energy equations and empirically determined variables. As a result, a more or less uniform flow over the web width can be achieved for a small operating area of the paper machine. A variation of the throughput amounts leads to clear differences in the distribution of the fiber orientation over the web width.
  • the fiber orientation is also influenced by pressure and temperature-related deviations in parallelism in the flow and nozzle channels, by cross-sectional differences in the tube bundle and in the turbulence tube bundle (deposits, etc.) and by different wall friction across the width and in the peripheral zones.
  • the object of the invention is to provide a headbox in which the disadvantages described above are avoided, so that the fiber orientation is formed uniformly over the entire web width and the headbox can easily be adapted to different operating conditions. Furthermore, it should be possible to various paper types and headbox constructions can dispense with an aperture control and / or the arrangement of a mixing chamber between the distribution pipe and the nozzle chamber. The control and regulation of the headbox should be possible during the paper production process, suitable measuring methods providing the required control variables.
  • the invention is primarily characterized in that the flow cross section of the tube bundle is variable over the width of the headbox in order to control and / or regulate the headbox.
  • the tube bundle is divided zone by zone into zone chambers, the flow cross section of each zone chamber being controllable and / or adjustable.
  • the zone chambers preferably comprise flow tubes made of flexible material, which can be compressed by pressure medium, so as to change the flow cross section.
  • FIG. 1 shows a schematic overview of the arrangement according to the invention.
  • 2 and 3 schematically show sectional views through various embodiments of the tube bundle.
  • 4 to 10 illustrate embodiments of the arrangement according to the invention in various cuts and cracks.
  • the paper machine for the headbox according to the invention is only hinted at. It comprises a rotating screen 1, which is deflected around a roller 2, such as a breast roller 2 or a suction roller 2a.
  • the fiber suspension is applied to the screen 1 via the stock outlet nozzle 3 and fed from the screen for further processing.
  • the Fiber suspension is fed to the headbox via the distribution pipe 4 and reaches the outlet nozzle 3 via the flow channel 5 serve to feed the substance to the discharge nozzle 3 as evenly as possible.
  • the tube bundle is divided zone by zone into zone chambers 7 and each of these zone chambers can be pressurized by pressure medium.
  • Hydraulic cylinders 8 are shown schematically, each of which is connected to the associated zone chamber 7 with a pressure line on the pressure side. The mode of operation is further explained below.
  • the flow cross-section of each individual zone chamber is controlled by the hydraulic cylinders, so that the material outlet can be controlled or regulated over the entire width of the headbox and the paper web formed on the screen 1.
  • a traversing measuring head 9 is arranged which continuously detects a fiber orientation profile of the paper web. This fiber orientation profile and / or basis weight profile serves as a measurement variable for controlling the headbox.
  • the measurement data of the measuring head 9 reach the schematically indicated computer system 11 via the lines 10, the measurement data representing the basis weight and / or the fiber orientation of the paper web formed.
  • Signals reach the computer system via the line 12 and are a function of the outlet pressure prevailing in the outlet nozzle 3.
  • a pressure transmitter is shown schematically at 13 and a converter at 14.
  • measurement data relating to the prevailing pressure in the regulating device come from the zone chambers 7 via the line 15 to the computer system 11 and the computer system returns the calculated setpoint value for each individual zone chamber, which then gives the associated hydraulic cylinder 8 controls.
  • the individual controls related to the individual values are compared with the setpoint, which is normally a straight line with a fiber orientation angle of 0 °.
  • the pressure in the corresponding zone chambers is increased or decreased, which leads to a corresponding change in cross-section of the flow tubes and thus to a decrease or increase in the flow rate of the substance.
  • the criteria for control operation are continuously monitored by the computer system. As already mentioned, this includes the basis weight (atro) of the paper web formed and the total pressure 13 in the headbox.
  • the type of inclusion of the basis weight in the control depends on whether the headbox is provided with or without a separate basis weight control device. In any case, the aim of the regulation is to achieve uniform fiber orientation across the width of the paper machine with an optimal basis weight profile. With the device according to the invention, optimal flow conditions can be set across the entire machine width.
  • the arrangement of a tube bundle in the flow channel 5 is known per se and serves to supply the stock suspension 3 with the stock suspension as evenly as possible and with high turbulence.
  • the flow cross-section of the tube bundle is variable over the width of the headbox in order to control and / or regulate it.
  • the tube bundle consists of an arrangement of parallel through-flow tubes 16 (shown schematically in section), the arrangement extending over the entire width of the headbox.
  • each individual flow tube 16 can be controlled and regulated by a corresponding control device 17.
  • the flow tubes 16 are located in zone chambers 18, and the flow tubes lying within a zone chamber are controlled by the control devices 17.
  • the flow cross-section of the flow tubes can be controlled in a variety of ways within the scope of the invention.
  • the zone chamber 7 is made of elastic material and the flow tube 19 is also elastic.
  • the zone chamber wall 21 is pressed inwards, so that a pressure medium 22 (gas or liquid) located in the zone chamber in turn compresses the flow tube 19 and thus changes the flow cross section until the pressure prevailing in the flow tube p2 is equal to the pressure pl in the zone chamber.
  • the zone chamber made of elastic material is surrounded by a housing 24 made of rigid material, such as steel.
  • the pipe sockets 25, 26 serve to supply and remove the substance suspension.
  • Fig. 5 shows another embodiment for the control of the flow cross section.
  • the individual tubes 27 of the tube bundle are inserted in an end plate 28.
  • FIG. 5a shows the arrangement with a full flow cross section
  • FIG. 5b shows the arrangement with a reduced cross section.
  • the flow cross-section is reduced by compressing the rubber rings between the end plate 28 and the pressure plate 30.
  • the pressure plate 30 is zoned in several sections to the end plate 28, for example by a split or elastic design, each of these zones can be controlled separately become.
  • the distance to the end plate is achieved by different support (mechanical .. screws, etc.) across the width.
  • 6, 7 show, in mutually associated sections, another embodiment variant with mechanical control of the flow cross section.
  • the tube bundle here consists of three rows of flow tubes 27 lying one above the other and only the bottom row is changed zone by zone to control the flow rate.
  • the change in the flow cross-section takes place by means of pinch strips 31 arranged in zones, which can be adjusted by means of corresponding mechanical drive devices (spindle, electromagnets, hydraulics, etc.).
  • 6 shows the arrangement with a full flow cross section
  • FIG. 7 shows the arrangement with a reduced flow cross section of the lowest flow tube in a section along the line VII-VII.
  • the controlled zones along the width of the headbox are defined by the length of the squeeze strips 31. Zone chambers are not required here.
  • the mechanically acting squeezing device can easily be modified by any person skilled in the art in such a way that not only the bottom row of the flow tubes, but also others
  • Rows or all flow tubes can be changed in their flow cross-section.
  • the flow tubes 27 are arranged between two end plates 32.
  • the lowermost flow tube is interrupted over a section and the interruption is bridged by a flexible hose 33.
  • the squeeze strip 31 presses up, thereby squeezing the hose and reducing the flow cross-section.
  • the counter bearing 34 serves to limit the stroke and supports the hose accordingly.
  • Fig. 8 shows the cross section through a zone chamber made of rigid material, such as sheet steel.
  • this zone chamber either one flow tube 27 can be arranged or in a row several flow tubes, such as this would correspond to Fig. 3.
  • the flow tube 27 is interrupted and the interruption is bridged by the hose 33.
  • a stable zone chamber, which contains the pressure medium 36, is formed by the end plates 32 and the housing 35. Liquid or gas can be used as the pressure medium. If the pressure or the volume of the pressure medium 36 is increased by any means, the flexible hose 33 is compressed and thus narrows the flow cross-section, as indicated by the arrow 37.
  • the pressure in the zone chamber can be increased, for example, by pumping in the pressure medium, by pressing a liquid-displacing object into the pressure medium 36, by heating, etc.
  • the zone chamber consists of a flexible plastic insert, which forms both the wall 37 of the zone chamber and the flow tubes 38.
  • the zone chamber space 39 for receiving the pressure medium remains between the wall 37 and the flow tubes 38.
  • the plastic insert is surrounded on the outside by a rigid housing 40.
  • the flow tubes 41 of the tube bundle are tightly connected to the flow tubes 38.
  • Pressure medium can be pressed into the zone chamber space 39 via the connection 42, the flexible flow tubes 38 being compressed in the manner already described and thus reducing the flow cross-section.

Abstract

Une caisse de tête pour machines à papier comprend au moins un faisceau de tubes d'écoulement direct agencés dans le canal d'écoulement entre le tuyau de distribution, qui fournit la pâte à papier, et l'ajutage de décharge. La section transversale d'écoulement direct du faisceau de tubes ou des tubes à écoulement direct (16, 27, 38) peut être modifiée dans le sens de la largeur de la caisse de tête à des fins de réglage et/ou d'ajustement de la caisse de tête.
EP19890905581 1988-05-17 1989-05-12 Caisse de tete pour machines a papier Withdrawn EP0366768A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT1288/88A AT392989B (de) 1988-05-17 1988-05-17 Stoffauflauf fuer papiermaschinen
AT1288/88 1988-05-17

Publications (1)

Publication Number Publication Date
EP0366768A1 true EP0366768A1 (fr) 1990-05-09

Family

ID=3510650

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890905581 Withdrawn EP0366768A1 (fr) 1988-05-17 1989-05-12 Caisse de tete pour machines a papier

Country Status (3)

Country Link
EP (1) EP0366768A1 (fr)
AT (1) AT392989B (fr)
WO (1) WO1989011561A1 (fr)

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03249297A (ja) * 1990-02-26 1991-11-07 Mitsubishi Heavy Ind Ltd 抄紙機ヘッドボックスの流向調整方法
US5196091A (en) * 1991-10-29 1993-03-23 Beloit Technologies, Inc. Headbox apparatus with stock dilution conduits for basis weight control
DE4211290C2 (de) * 1992-04-03 1994-07-07 Voith Gmbh J M Mischeinrichtung mit veränderlichen Rohrquerschnitten zum Mischen von zwei Flüssigkeiten bei konstantem Gemischvolumenstrom zur Versorgung des Stoffauflaufs einer Papiermaschine
DE4213707A1 (de) * 1992-04-25 1993-10-28 Escher Wyss Gmbh Stoffauflaufeinrichtung für eine Papiermaschine
JP3021219B2 (ja) * 1992-10-29 2000-03-15 三菱重工業株式会社 抄紙機ヘッドボックスの端部流量調整装置
DE4237305C2 (de) * 1992-11-05 1994-07-07 Voith Gmbh J M Turbulenzeinsatz mit variabler Geometrie für einen Stoffauflauf einer Papiermaschine
DE4409415C5 (de) * 1994-03-18 2005-02-17 Voith Sulzer Papiermaschinen Gmbh Dosiervorrichtung für einen Stoffauflauf einer Papiermaschine
EP0774540B1 (fr) 1995-11-17 2002-02-27 Voith Paper Patent GmbH Procédé pour régler la longueur de rupture dans le sens transversal d'une bande fibreuse en mouvement
DE19634996C2 (de) 1996-08-30 2000-05-25 Voith Sulzer Papiermasch Gmbh Stoffdichtegeregelter Stoffauflauf mit Papierstoffkonsistenzregelung
DE19634997C2 (de) 1996-08-30 1999-08-05 Voith Sulzer Papiermasch Gmbh Regeleinrichtung mit einer Sensoren-Mehrzahl
DE19733454A1 (de) 1997-08-02 1999-02-04 Voith Sulzer Papiermasch Gmbh Verfahren und Vorrichtung zur Erkennung und Korretur einer Faserorientierungs-Querprofil-Veränderung
US6004431A (en) * 1998-02-24 1999-12-21 Beloit Technologies, Inc. Headbox with active local flow control
FI115647B (fi) * 1998-12-23 2005-06-15 Metso Paper Inc Paperikoneen/kartonkikoneen perälaatikon säätömenetelmä ja paperikoneen/kartonkikoneen perälaatikkorakenne

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3038538A (en) * 1958-05-28 1962-06-12 Kenneth C Logan Paper machine headbox
FR1405258A (fr) * 1964-05-06 1965-07-09 Grenobloise Etude Appl Dispositif à perte de charge variable
GB1562296A (en) * 1975-10-29 1980-03-12 Beloit Corp Paper-making machine stock supply system
DE3514554C3 (de) * 1984-09-19 1998-01-08 Escher Wyss Gmbh Stoffauflauf-Vorrichtung für eine Papiermaschine und Verfahren zu deren Betrieb
CA1303706C (fr) * 1985-01-22 1992-06-16 Gurcan Aral Systeme et procede de controle de formation de materiau en feuilles
FI73766C (fi) * 1985-12-13 1987-11-09 Ahlstroem Oy INLOPPSLAODA FOER PAPPERSMASKIN. SIIRRETTY PAEIVAEMAEAERAE-FOERSKJUTET DATUM PL 14 ç 17.12.85.
AT384633B (de) * 1986-05-12 1987-12-10 Albert Hans Stoffauflauf fuer papiermaschinen

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8911561A1 *

Also Published As

Publication number Publication date
WO1989011561A1 (fr) 1989-11-30
ATA128888A (de) 1990-12-15
AT392989B (de) 1991-07-25

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