WO1994012724A1 - Appareil detecteur de rupture de feuille - Google Patents

Appareil detecteur de rupture de feuille Download PDF

Info

Publication number
WO1994012724A1
WO1994012724A1 PCT/US1993/009974 US9309974W WO9412724A1 WO 1994012724 A1 WO1994012724 A1 WO 1994012724A1 US 9309974 W US9309974 W US 9309974W WO 9412724 A1 WO9412724 A1 WO 9412724A1
Authority
WO
WIPO (PCT)
Prior art keywords
transducer
vacuum
sheet
sheet break
vacuum level
Prior art date
Application number
PCT/US1993/009974
Other languages
English (en)
Inventor
Jeffrey H. Pulkowski
Original Assignee
Beloit Technologies, Inc.
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 Beloit Technologies, Inc. filed Critical Beloit Technologies, Inc.
Priority to EP93924356A priority Critical patent/EP0660898B1/fr
Priority to DE69304545T priority patent/DE69304545T2/de
Priority to DE0660898T priority patent/DE660898T1/de
Priority to PL93308218A priority patent/PL172455B1/pl
Priority to KR1019950702070A priority patent/KR950704569A/ko
Priority to BR9307486A priority patent/BR9307486A/pt
Publication of WO1994012724A1 publication Critical patent/WO1994012724A1/fr
Priority to FI952548A priority patent/FI952548A0/fi

Links

Classifications

    • 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

  • PATENT APPLICATION TITLE A SHEET BREAK DETECTOR APPARATUS
  • the present invention relates to a sheet break detector apparatus for detecting a sheet break in a dryer section of a paper machine. More particularly, the present invention relates to a sheet break detector for particular application to a dryer section having no open draws therein.
  • Bel-Champ is a common law trademark of Beloit Corporation.
  • the Bel-ChampTM single tier drying section has provided a means for drying alternate sides of a web of paper without subjecting the paper to the long open draws typically incorporated into a conventional two-tier, double felted dryer section.
  • the excellent runnabiiity of the Bel-ChampTM also contributes to the increased likelihood that the web will wrap one of the dryers.
  • the geometry of the Bel-ChampTM dryer section makes it difficult to remove the wrapped paper from the dryer if the wound layers around the drying cylinder become excessively thick.
  • a reliable sheet break detector would sense the absence of a web and would initiate a dropping of the sheet upstream relative to the dryer section, thereby preventing excessive wrapping of a dryer cylinder.
  • the Bel-ChampTM concept does not include any open draws. Therefore, the employment of a conventional sheet break detector is not possible.
  • a prior art break detection method includes an optical sensor to determine if a web is present.
  • a light emitter is located on one side of the web and a receiver on the other. When a web is running between the emitter and receiver, the passage of light is obstructed, indicating the presence of the web.
  • an optical sensor includes an emitter and a receiver.
  • the emitter and receiver are located on the same side of the web.
  • Such configuration utilizes reflected light rather than transmitted light in order to detect the presence of a web.
  • the sensor is of a type that can detect a color difference. Therefore, in order for the aforementioned method to be effective, a colored felt must be used. The sensor senses the color difference between a felt and a sheet of paper so that in the event of a sheet break, such color difference is sensed by the sensor.
  • optical sensors are sensitive to dust and the build-up of dirt on the light sensitive lenses thereof. Such build-up of dust and dirt restricts the passage of light, thus indicating the presence of a web even when the web is absent due to a web breakage. When such a false indication occurs, there can be a significant amount of paper wrapped up on a dryer before a sheet break is discovered. Cleaning the wrapped paper from the dryer cylinder leads to excessive downtime of the dryer section.
  • Vacuum sensors are not as sensitive to dust and dirt as optical transducer type counterparts.
  • the present invention provides a vacuum transducer for detecting a sheet break which is insensitive to operational changes in the normal adjustments in vacuum levels of the vacuum rolls, while reliably detecting a sheet break.
  • Another object of the present invention is the provision of a vacuum sheet break detecting apparatus which overcomes the aforementioned problems of the prior art arrangements and which makes a considerable contribution to the art of detecting a sheet break in a dryer section.
  • the present invention relates to a sheet break detector apparatus and method for detecting a sheet break in a dryer section of a paper machine.
  • the apparatus includes a vacuum transducer which is sensitive to the vacuum level within a vacuum roll of the dryer section.
  • the transducer detects only a sudden change in the vacuum level within the vacuum roll resulting from a sheet break, rather than a relatively gradual change in the vacuum level resulting from an operator augmented vacuum level change.
  • the apparatus also includes means connected to the transducer and responsive to the transducer for redirecting the sheet to a broke chute or pit upstream relative to the transducer when the transducer detects the sudden change in vacuum level.
  • the arrangement is such that excessive wind-up of the broken sheet around a dryer of the dryer section is inhibited.
  • the transducer is a piezoelectric pressure transducer which senses the vacuum level within a center shaft of the vacuum roll.
  • the transducer senses the vacuum level within a duct which connects the vacuum roll to a source of partial vacuum.
  • the transducer is such that during normal operation of the dryer section, when the unbroken sheet extends through the dryer section, a first output from the transducer is zero, and when a sheet break occurs, an output signal is generated which is proportional to the change in vacuum level within the vacuum roll as a result of the sheet break.
  • Figure 1 is a side-elevational view of a portion of a Bel-ChampTM type dryer section showing the location of the transducer;
  • Figure 2 is a similar view to that shown in Figure 1 , but shows how the web is directed to a broke chute or pit in the event of a downstream web breakage;
  • FIG. 3 is a schematic representation of a sheet break detector apparatus including a vacuum transducer according to the present invention
  • Figure 4 is a schematic representation of the sheet detector apparatus according to a further embodiment of the present invention in which the transducer detects the vacuum level within a duct;
  • Figure 5 is a graph showing the transducer response to a steady state condition
  • Figure 6 is a graph showing the transducer response to a sheet break.
  • Figure 7 is a graph showing the transducer response to an operator augmented damper adjustment.
  • FIG. 1 is a side-elevational view of a portion of a Bel-ChampTM type dryer section including a sheet break detector apparatus, generally designated 10 according to the present invention, for detecting a sheet break in the dryer section, generally designated 12.
  • the apparatus 10 includes a vacuum transducer 14 which is sensitive to the vacuum level within a vacuum roll 16 of the dryer section 12.
  • the transducer 14 detects only a sudden change in the vacuum within the vacuum roll 16 resulting from a sheet break rather than a relatively gradual change in vacuum resulting from an operator augmented vacuum level change.
  • Figure 2 is a view similar to that shown in Figure 1 , but showing the operation of the apparatus 10 in the event of a web breakage. More particularly, means 18 are connected to the transducer 14 and responsive to the transducer 14 for redirecting the sheet W to a broke pit 22 disposed upstream relative to the transducer 14 when the transducer 14 detects a sudden change in vacuum level. The' arrangement is such that excessive wind-up of the broken web W around a dryer 24 of the dryer section 12 is inhibited.
  • the broken web W is shown as wrapping around dryer cylinder 24 and the trailing end of the downstream broken web passing the vacuum roll 16 in order to extend around drying cylinder 26.
  • the means 18 may include a transverse web cutting device for cutting the web as it extends around a vacuum transfer roll 28. Additionally, the means 18 may include an arrangement for cutting off the vacuum to the vacuum roll 28 such that the moving web will fall to the broke pit 22 rather than extending around the vacuum roll 28 for transfer into the downstream dryer group, which includes drying cylinders 24 and 26 and vacuum roll 16.
  • the present invention is directed particularly to the transducer 14, which senses the sudden change in vacuum level, and it will be understood by those skilled in the art that such transducer may be used for triggering a visual or audible alarm so that an operator may manually direct the web to the broke pit.
  • the aforementioned transducer 14 may generate a signal for cutting the web upstream of the entire dryer group or, for in any other manner, interrupting the movement of the web along the dryer section.
  • the transducer 14 is a piezoelectric pressure transducer.
  • Figure 3 is a schematic representation showing the transducer 14 for sensing the vacuum level existing within a center shaft 30 of the vacuum roll 16.
  • FIG 4 is a similar view to that shown in Figure 3, but shows an alternative embodiment of the present invention in which a transducer 14A senses the vacuum level within a duct 32 which connects the vacuum roll 16A to a source of partial vacuum 34.
  • the transducer 14 is arranged in such a manner that during normal operation of the dryer section 12, when the unbroken web W extends through the dryer section 12, the output from the transducer is zero.
  • the change in vacuum is sensed by the transducer and an output signal is generated which is proportional to the change in vacuum level within the vacuum roll 16 as a result of the sheet break.
  • Figure 5 is a graph 36 showing the response of the piezoelectric transducer 14 to a steady state condition with the graph 36 representing the pressure against a number of time constants.
  • Figure 6 shows four graphs 38,40,42 and 44 indicating the transducer output for various time constants in response to a sheet break.
  • Figure 7 shows graphs 46,48 and 50 indicating the response of the transducer 14 to routine damper adjustments of the vacuum roll for various time constants.
  • Figure 7 shows the graphs for the pressure relative to the time of adjustment.
  • the output from the transducer 14 decays to zero when a new steady state condition exists, as shown particularly in the graph 44 shown in Figure 6, following the sheet break.
  • the difference in the output signal between a fast and a relatively slow change makes it possible to detect the difference between a sheet break and damper movement.
  • the time constant is within the range 1 millisecond to 3 seconds.
  • the time constant is defined as the period required for the output to reach e ' ⁇ or .368, of its original value.
  • Figure 5 shows the graph 36 of this curve.
  • the objective is to configure the transducer system such that it has a time constant on the order of milliseconds.
  • the vacuum change occurring during a sheet break happens fast enough to be fully sensed by the transducer, as shown in the graph depicted in Figure 6.
  • the much slower change in vacuum that occurs when an operator adjusts a vacuum damper is competing with the constantly decaying output of the transducer. Given a sufficiently short time constant, the sensor will exhibit only a slight ripple in its output, as shown in Figure 7.
  • the means may include a cross-machine web cutter such that the web is directed to the broke chute 22.
  • the means may include an audible or visible alarm for directing an operator to the presence of a sheet break.
  • the present invention provides a reliable means for detecting a sheet break that is particularly advantageous for detecting a sheet break within a dryer section having no open draws.

Landscapes

  • Paper (AREA)
  • Controlling Rewinding, Feeding, Winding, Or Abnormalities Of Webs (AREA)
  • Controlling Sheets Or Webs (AREA)

Abstract

L'invention concerne un appareil détecteur de rupture de feuille (10) conçu pour détecter la rupture d'une feuille dans la section sécheur (12) d'une machine à fabriquer le papier. L'appareil (10) comporte un transmetteur à vide (14) qui est sensible au niveau de vide dans un tambour à vide (16) du sécheur (12). Le transmetteur (14) détecte seulement une variation brusque du niveau de vide dans le tambour à vide (16) provoquée par la rupture de la feuille, plutôt qu'une variation relativement graduelle du niveau de vide provoquée par l'action d'un opérateur. Un dispositif de guidage est relié au transmetteur (14) et en réponse à celui-ci, il redirige la feuille vers une chute de réception (22) située en amont du transmetteur (14), lorsque celui-ci détecte la variation brusque du niveau de vide. L'appareil est conçu de façon à empêcher un enroulement excessif de la feuille déchirée (W) autour du sécheur (24) de la section de séchage (12).
PCT/US1993/009974 1992-11-25 1993-10-19 Appareil detecteur de rupture de feuille WO1994012724A1 (fr)

Priority Applications (7)

Application Number Priority Date Filing Date Title
EP93924356A EP0660898B1 (fr) 1992-11-25 1993-10-19 Appareil detecteur de rupture de feuille
DE69304545T DE69304545T2 (de) 1992-11-25 1993-10-19 Vorrichtung zur bruchdetektion einer bahn
DE0660898T DE660898T1 (de) 1992-11-25 1993-10-19 Vorrichtung zur bruchdetektion einer bahn.
PL93308218A PL172455B1 (pl) 1992-11-25 1993-10-19 Urzadzenie do wykrywania zerwania wstegi papieruw sekcji suszarek maszyny papierniczej PL PL PL PL PL PL PL
KR1019950702070A KR950704569A (ko) 1992-11-25 1993-10-19 시이트 파괴 감지 장치(a sheet break detector apparatus)
BR9307486A BR9307486A (pt) 1992-11-25 1993-10-19 Aparelho detector de ruptura de folha
FI952548A FI952548A0 (fi) 1992-11-25 1995-05-24 Rainan katkeamisen ilmaisulaite

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US98157992A 1992-11-25 1992-11-25
US07/981,579 1992-11-25

Publications (1)

Publication Number Publication Date
WO1994012724A1 true WO1994012724A1 (fr) 1994-06-09

Family

ID=25528481

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1993/009974 WO1994012724A1 (fr) 1992-11-25 1993-10-19 Appareil detecteur de rupture de feuille

Country Status (13)

Country Link
EP (1) EP0660898B1 (fr)
JP (1) JP2562799B2 (fr)
KR (1) KR950704569A (fr)
CN (1) CN1035076C (fr)
BR (1) BR9307486A (fr)
CA (1) CA2150021C (fr)
DE (2) DE69304545T2 (fr)
FI (1) FI952548A0 (fr)
MX (1) MX9307387A (fr)
MY (1) MY110025A (fr)
PL (1) PL172455B1 (fr)
TW (1) TW229270B (fr)
WO (1) WO1994012724A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6340412B1 (en) * 1998-04-27 2002-01-22 Fotocomp Oy Method for determining the detaching angle and/or the detaching profile of a paper web
EP1186702A2 (fr) * 2000-08-28 2002-03-13 Voith Paper Patent GmbH Procédé pour le contrôle de la rupture d' une bande

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004046795A1 (de) 2004-09-27 2006-04-06 Voith Paper Patent Gmbh Einrichtung und Verfahren zur Überwachung des Überführens einer Materialbahn und speziell der Verbreiterung der Breite eines Überführstreifens auf einen Abriss des Überführstreifens oder der Materialbahn
DE102007000679A1 (de) 2007-11-09 2009-05-14 Voith Patent Gmbh Verfahren und Vorrichtung zum Erfassen eines Risses und/oder eines Elastizitätsmoduls einer Materialbahn
ES2731276T3 (es) 2016-08-29 2019-11-14 Siemens Ag Procedimiento para el funcionamiento de una máquina para la fabricación y/o el tratamiento de una banda de material
CN107164987B (zh) * 2017-07-14 2019-02-19 河南卷烟工业烟草薄片有限公司 一种大缸损纸及纸屑收集装置
JP6902270B2 (ja) * 2017-10-02 2021-07-14 デュプロ精工株式会社 帯状物形成装置
CN110877839B (zh) * 2018-09-06 2022-03-25 西门子（中国）有限公司 断纸的处理方法及设备
EP3699356A1 (fr) * 2019-02-25 2020-08-26 Siemens Aktiengesellschaft Procédé et dispositif de détection d'une déchirure d'un bande de fibre, installation industrielle ainsi que produit programme informatique
CN110906972B (zh) * 2019-10-28 2021-06-18 浙江大学山东工业技术研究院 一种纸张监测自动防断系统

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1725108A (en) * 1926-03-10 1929-08-20 Alvin W Smith Method and apparatus for making paper
US1838603A (en) * 1929-07-11 1931-12-29 Sr George S Witham Paper making machine
GB947294A (en) * 1961-05-23 1964-01-22 Dominion Eng Works Ltd Improvements in or relating to papermaking machines

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1725108A (en) * 1926-03-10 1929-08-20 Alvin W Smith Method and apparatus for making paper
US1838603A (en) * 1929-07-11 1931-12-29 Sr George S Witham Paper making machine
GB947294A (en) * 1961-05-23 1964-01-22 Dominion Eng Works Ltd Improvements in or relating to papermaking machines

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6340412B1 (en) * 1998-04-27 2002-01-22 Fotocomp Oy Method for determining the detaching angle and/or the detaching profile of a paper web
EP1186702A2 (fr) * 2000-08-28 2002-03-13 Voith Paper Patent GmbH Procédé pour le contrôle de la rupture d' une bande
EP1186702A3 (fr) * 2000-08-28 2003-08-13 Voith Paper Patent GmbH Procédé pour le contrôle de la rupture d' une bande

Also Published As

Publication number Publication date
FI952548A (fi) 1995-05-24
DE660898T1 (de) 1996-01-18
CA2150021C (fr) 1998-09-01
TW229270B (fr) 1994-09-01
JP2562799B2 (ja) 1996-12-11
PL172455B1 (pl) 1997-09-30
CN1088647A (zh) 1994-06-29
EP0660898A1 (fr) 1995-07-05
DE69304545D1 (de) 1996-10-10
DE69304545T2 (de) 1997-02-06
FI952548A0 (fi) 1995-05-24
BR9307486A (pt) 1999-08-24
KR950704569A (ko) 1995-11-20
PL308218A1 (en) 1995-07-24
CA2150021A1 (fr) 1994-06-09
MY110025A (en) 1997-11-29
EP0660898B1 (fr) 1996-09-04
MX9307387A (es) 1994-06-30
JPH07507604A (ja) 1995-08-24
CN1035076C (zh) 1997-06-04

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