EP1925725A1 - Procédé pour détecter une rupture d'une bande fibreuse et une toile de séchage pour la mise en oeuvre du procédé - Google Patents

Procédé pour détecter une rupture d'une bande fibreuse et une toile de séchage pour la mise en oeuvre du procédé Download PDF

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Publication number
EP1925725A1
EP1925725A1 EP07118866A EP07118866A EP1925725A1 EP 1925725 A1 EP1925725 A1 EP 1925725A1 EP 07118866 A EP07118866 A EP 07118866A EP 07118866 A EP07118866 A EP 07118866A EP 1925725 A1 EP1925725 A1 EP 1925725A1
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EP
European Patent Office
Prior art keywords
color pattern
fibrous web
characteristic color
web
drying
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Withdrawn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
EP07118866A
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German (de)
English (en)
Inventor
Armin Bauer Dr.
Robert Kling
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.)
Voith Patent GmbH
Original Assignee
Voith Patent GmbH
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 Voith Patent GmbH filed Critical Voith Patent GmbH
Publication of EP1925725A1 publication Critical patent/EP1925725A1/fr
Withdrawn legal-status Critical Current

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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F7/00—Other details of machines for making continuous webs of paper
    • D21F7/04—Paper-break control devices

Definitions

  • the invention relates to a method for detecting a tear of a fibrous web in a dryer section of a machine for producing the fibrous web, wherein the fibrous web is passed through at least one drying wire through the dryer section, wherein the tear is detected by at least one device for web tear detection and wherein a tee for the fibrous web is activated by the web break detection means.
  • the invention relates to a dryer fabric for a dryer section of a machine for producing a fibrous web, in particular for carrying out the method according to the invention.
  • photocells are not suitable in situations in which the fibrous web on a serving as a web support, such as a forming fabric, a press felt or a dryer fabric, rests.
  • a serving as a web support such as a forming fabric, a press felt or a dryer fabric
  • optical systems for example laser or optical waveguide sensors, are used here, in which a detector and a light or radiation source of the device for web break detection are mounted on the same side of the fibrous web.
  • FIG. 1 is an example of the waveform of an optical device for web tear detection in the occurrence of a web break in a color intensity-time diagram (Ft diagram) outlined.
  • a signal is given to a stripping device.
  • the trigger threshold value S for the signal to the tee device may be 50% of the color intensity F.
  • a disadvantage of color recognition systems is that they become all the more unreliable the smaller the color difference between the fibrous web and the dryer fabric. This is the case, for example, in machines for producing cardboard or packaging papers where brownish paper or board webs rest on red or amber dry sieves. Here it can no longer be clearly differentiated between fibrous web and dryer fabric. This results in either a web tear detection without demolition or a demolition without web tear detection. The former leads to an unnecessary production shutdown and thus to financial losses for the A-lagenbetreiber, the latter carries the risk of damaging the machine in itself.
  • dryer fabrics can become very dirty with increasing service life, whereby the actual color of the dryer fabric is covered by the dirt deposits. In such cases, it has been found that a color detection system also no longer works reliably.
  • the invention is therefore based on the object, a method and a dryer fabric of the types mentioned in such a way that in comparison to the prior art, a more reliable detection of web breaks in particular single-row dryer sections of a machine for producing a fibrous web is made possible.
  • This object is achieved in a method of the type mentioned above in that a drying wire is used with at least one charateristic color pattern, which is reliably detected in the case of demolition of the fibrous web of the device for web tear detection.
  • the Reliability of the detection of the tear of the fibrous web markedly improved, in particular with regard to the conventional method.
  • a further advantage of the method according to the invention is that the at least one color pattern to be detected is substantially larger than the structures of the dryer fabric and thus less susceptible to soiling in the dryer fabric.
  • color refers to light with a specific wavelength or even light from a specific wavelength range, such as the R channel in an RGB sensor. UV and IR radiation are included.
  • the characteristic color pattern of the dryer fabric is formed by a plurality of differently colored and preferably transverse to the running direction of the color strip.
  • the color strips of the dryer fabric in this case can have a variety of different colors. This multicolor also contributes to a significant improvement in the reliability of the demolition detection.
  • the characteristic color pattern of the dryer fabric is preferably formed by a plurality of differently colored threads.
  • targeted and relatively inexpensive influence on its subsequent use can be taken already in the production of the dryer.
  • the characteristic color pattern is preferably produced by differently dyed weft threads in a woven dryer fabric.
  • white polytetrafluoroethylene and for the warp threads red polyester can be used.
  • the base color of the dryer fabric may be red, every 30 cm there may be a white color stripe, with a black color stripe next to each fourth white color stripe.
  • a thread thickness of the weft thread is preferably used as the minimum width for the characteristic color pattern.
  • the characteristic color pattern in a spiral wire can preferably be produced by differently colored spirals.
  • Spiral screens which consist of differently colored spirals, are due to the nature of the production of spiral screens without much additional additional effort and thus without considerable additional costs compared to single-color screens produce.
  • a spiral thickness of the spiral is preferably used as the minimum width for the characteristic color pattern.
  • the maximum width of the characteristic color pattern may result from the maximum permissible web length, which still causes no damage to the machine for producing the fibrous web, before the tee device is activated by the web break detection device.
  • a typical value would be, for example, 10 m track length, that is to say the color pattern on the drying screen should repeat every 10 m at the latest. Color strips that are much wider than 10 m would therefore make no sense.
  • the color stripes of the characteristic color pattern may vary in width.
  • a dryer fabric may consist of 90 cm wide red and 10 cm wide white color stripes.
  • the characteristic color pattern can also be produced by a subsequent coloring of the dryer fabric, preferably by means of a thermography. This provides the advantage that the same dryer fabrics, optionally produced in larger quantities to lower unit costs, due to different Colorings can be made useful for different cases.
  • a drying wire with a characteristic color pattern arranged only in regions can also be used.
  • the color strips can therefore only have a certain strip length, that is, they do not necessarily have to extend over the entire width of the dryer fabric. This may provide the advantage of reduced manufacturing costs for the dryer fabric under certain circumstances.
  • the detection of the tear of the fibrous web can be carried out according to the invention by means of various measuring methods: Thus, a point measurement, such as a laser beam, a light beam or the like, a line measurement, such as a line scan camera or the like, and / or a surface measurement, such as a CCD camera or the like. All measurement methods are characterized by high reliability and good usability even in difficult environments.
  • a difference between a non-periodic, in particular stochastic signal of the fibrous web and a periodic signal of the characteristic color pattern can be used. It is therefore necessary to detect the color change of the color stripes or also the periodic signal caused by the color change.
  • the detected outline of the fibrous web is preferably evaluated by means of a Fourier or power spectrum of the signal, at least one triggering threshold being set at a frequency characteristic of the drying wire.
  • the characteristic triggering frequency results from the width of the colored strip and the speed of the fibrous web.
  • the characteristic frequency can be set by the choice of the widths of the color stripes.
  • the object of the invention is achieved in a dryer fabric of the type mentioned in that it is provided with at least one characteristic color pattern, which is reliably detected in the case of demolition of the fibrous web by a demolition detector.
  • FIG. 2 is a side view of a section of a dryer section 2 of a generally designated 1 machine for producing a fibrous web 3 shown.
  • the dryer section 2 within the machine 1 fulfills the function of extracting moisture from a manufactured and / or processed fibrous web 3, ie drying it.
  • each of the dryer fabrics 5 each circulating a group of drying cylinders 4. More specifically, each drying wire 5 in the region of the drying cylinder 4 is wavy up and down, wherein the drying wire 5 is deflected at the wave crest of a drying cylinder 4 and is deflected in the trough by a suction roll of a respective vacuum device 6. After leaving the last drying cylinder 4 of the corresponding group, the drying wire 5 is returned via a plurality of guide rollers 7 back to the first drying cylinder 4 of the group.
  • At least one symbolically indicated device 8 for web tear detection is provided for each group of drying cylinders 4, which will be described later.
  • at least one tee-off device 9 for the fibrous web 3, which is only indicated schematically, is provided, which is activated by the device 8 for web tear detection.
  • a yarn-woven fabric dryer 5 having at least one characteristic color pattern 10 is used, which is reliably detected in the case of demolition of the fibrous web 3 by the device 8 for web tear detection.
  • a dot measurement such as a laser beam, a light beam or the like, a line measurement such as a line camera or the like, and / or an area measurement such as a CCD camera or the like are used. Since these preferred measuring methods are known to the person skilled in the art, their further description is not discussed here.
  • a difference between a non-periodic, in particular stochastic signal of the fibrous web 3 and a periodic signal of the characteristic color pattern 10 is used to detect the tear of the fibrous web 3.
  • the color change of the characteristic color pattern 10 or also the periodic signal caused by the color change of the characteristic color pattern 10 must be detected.
  • the detected outline of the fibrous web 3 is evaluated by means of a Fourier or power spectrum of the signal, at least one triggering threshold value S being set at a frequency f characteristic of the drying wire 5 (cf. FIG. 4 ).
  • the characteristic triggering frequency results from the width of the characteristic color pattern 10 and the speed v (arrow) of the fibrous web 3.
  • FIG. 3 shows an exemplary waveform of a solution according to the invention in a color intensity-time diagram (Ft diagram).
  • a signal is applied to the signal in the FIG. 2 indicated tee 9 of the corresponding group of drying cylinders 4 given.
  • the tripping threshold S for the signal to the tee device for example, at 50% of the color intensity F lie.
  • the FIG. 4 shows a detection of a tear of a fibrous web by a Fourier spectrum, once in the situation before demolition (left) and once in the situation after the demolition (right).
  • the characteristic frequency f of the corresponding color pattern is shown.
  • the characteristic frequency f does not exceed the tripping threshold value S.
  • the characteristic frequency f exceeds the tripping threshold value S at least once, thereby applying a signal to that in the FIG. 2 indicated tee 9 of the corresponding group of drying cylinders 4 is generated.
  • FIG. 5 shows a fragmentary plan view of a formed of threads 11 dryer fabric 5, which has a first embodiment of a characteristic color pattern 10.
  • FIG. 6 shows a fragmentary plan view of a formed from spiral threads 12 dryer fabric 5, which has a second embodiment of a characteristic color pattern 10.
  • each drying wire 5 is provided with at least one characteristic color pattern 10, which is reliably detected in the case of the tear of the fibrous web 3 by a demolition detector of the device 8 for web tear detection (see. FIG. 2 ).
  • the characteristic color pattern 10 each in the FIG. 5 shown dryer fabric 5 consists of several differently colored and preferably transverse to the direction L (arrow) aligned color stripes 13, which in turn preferably consist of several preferably differently colored threads 14.
  • the characteristic color pattern 10 each in the FIG. 5 shown dryer fabric 5 consists of several differently colored and preferably transverse to the direction L (arrow) aligned color stripes 13, which in turn preferably consist of several preferably differently colored threads 14.
  • only one color strip 13 is shown, which consists of seven different colored threads 14 consists.
  • different threads 14 may of course have the same color.
  • the characteristic color pattern 10 in the woven dryer fabric 5 is the FIG. 5 from seven preferably differently colored weft threads 14.
  • the weft threads 14 are made of white polytetrafluoroethylene and the warp threads 15 made of red polyester.
  • the dryer fabric 5 may have the base color red and have a white color strip every 30 cm, with a black color strip next to every fourth white color strip.
  • the characteristic color pattern 10 in a woven dryer fabric 5 has a minimum width Bmin in the range of a thread thickness DF of the weft thread 14.
  • the FIG. 6 the characteristic color pattern 10 by differently colored spirals 16.
  • the characteristic color pattern 10 has a minimum width Bmin in the region of a spiral thickness DS of the spiral 16.
  • the characteristic color pattern 10 has a maximum width Bmax, which results from the maximum permissible web length, which still causes no damage to the machine 1 for producing the fibrous web 3 before the teeper 9 is activated by the web break detection device 8 (see. FIG. 2 ).
  • the color stripes 13 may vary in width.
  • the dryer fabric 5 may consist of 90 cm wide red and 10 cm wide white color stripes 13.
  • the characteristic color pattern 10 may alternatively also consist of a subsequent coloring of the dryer fabric 5, preferably by means of a thermography known to the person skilled in the art, and it may also be present only in regions on the dryer fabric 5.
  • the color stripes 13 can have a certain length, that is, they do not necessarily have to extend over the entire transverse width of the drying wire 5.

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EP07118866A 2006-11-27 2007-10-19 Procédé pour détecter une rupture d'une bande fibreuse et une toile de séchage pour la mise en oeuvre du procédé Withdrawn EP1925725A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE102006055823A DE102006055823A1 (de) 2006-11-27 2006-11-27 Verfahren zur Erfassung eines Abrisses einer Faserstoffbahn in einer Trockenpartie einer Maschine zur Herstellung der Faserstoffbahn und Trockensieb zur Durchführung des Verfahrens

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EP1925725A1 true EP1925725A1 (fr) 2008-05-28

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EP07118866A Withdrawn EP1925725A1 (fr) 2006-11-27 2007-10-19 Procédé pour détecter une rupture d'une bande fibreuse et une toile de séchage pour la mise en oeuvre du procédé

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US (1) US20080121362A1 (fr)
EP (1) EP1925725A1 (fr)
DE (1) DE102006055823A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3452811A4 (fr) * 2016-05-06 2020-01-22 Procemex Oy Procédé et système de vision artificielle pour surveiller des processus de fabrication

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7986410B2 (en) * 2008-03-18 2011-07-26 Voith Patent Gmbh Method for detecting a fibrous web tear in a drying section of a machine for producing the fibrous web and apparatus for performing said method

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE9101972U1 (de) * 1991-02-20 1991-05-08 Thomas Josef Heimbach GmbH & Co, 5160 Düren Papiermaschinenbespannung
DE4216653A1 (de) * 1992-05-20 1993-11-25 Voith Gmbh J M Vorrichtung zum Durchtrennen einer Papierbahn in einer Pressenpartie einer Papiermaschine
DE19825368A1 (de) * 1998-06-06 1999-12-09 Heimbach Gmbh Thomas Josef Verfahren zum Einfärben von Teilbereichen einer technischen Textilbahn

Family Cites Families (5)

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Publication number Priority date Publication date Assignee Title
FR1597326A (fr) * 1968-12-30 1970-06-22
US4071899A (en) * 1976-07-09 1978-01-31 Hughes Aircraft Company System and method for the measurement of repetitive patterns
US4837715A (en) * 1987-01-27 1989-06-06 Kimberly-Clark Corporation Method and apparatus for detecting the placement of components on absorbent articles
US5150175A (en) * 1991-03-13 1992-09-22 American Research Corporation Of Virginia Optical imaging system for fabric seam detection
DE19831612A1 (de) * 1998-07-14 2000-01-20 Voith Sulzer Papiermasch Gmbh Meßsystem

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE9101972U1 (de) * 1991-02-20 1991-05-08 Thomas Josef Heimbach GmbH & Co, 5160 Düren Papiermaschinenbespannung
DE4216653A1 (de) * 1992-05-20 1993-11-25 Voith Gmbh J M Vorrichtung zum Durchtrennen einer Papierbahn in einer Pressenpartie einer Papiermaschine
DE19825368A1 (de) * 1998-06-06 1999-12-09 Heimbach Gmbh Thomas Josef Verfahren zum Einfärben von Teilbereichen einer technischen Textilbahn

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3452811A4 (fr) * 2016-05-06 2020-01-22 Procemex Oy Procédé et système de vision artificielle pour surveiller des processus de fabrication
US10884401B2 (en) 2016-05-06 2021-01-05 Procemex Oy Machine vision method and system for monitoring manufacturing processes
EP4019948A1 (fr) * 2016-05-06 2022-06-29 Procemex Oy Procédé et système de vision artificielle pour surveiller des processus de fabrication

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DE102006055823A1 (de) 2008-05-29

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