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WO1999044012A1 - Procede et appareil de mesure de l'epaisseur d'une bande continue en mouvement - Google Patents

Procede et appareil de mesure de l'epaisseur d'une bande continue en mouvement Download PDF

Info

Publication number
WO1999044012A1
WO1999044012A1 PCT/FI1999/000148 FI9900148W WO9944012A1 WO 1999044012 A1 WO1999044012 A1 WO 1999044012A1 FI 9900148 W FI9900148 W FI 9900148W WO 9944012 A1 WO9944012 A1 WO 9944012A1
Authority
WO
WIPO (PCT)
Prior art keywords
measuring
web
distance
heads
caliper
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.)
Ceased
Application number
PCT/FI1999/000148
Other languages
English (en)
Inventor
Hannu Moisio
Mauri Ojala
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.)
Valmet Automation Inc
Original Assignee
Valmet Automation 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 Valmet Automation Inc filed Critical Valmet Automation Inc
Priority to AU26262/99A priority Critical patent/AU2626299A/en
Publication of WO1999044012A1 publication Critical patent/WO1999044012A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
    • G01B11/0691—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of objects while moving
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
    • G01B21/02—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness
    • G01B21/08—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness for measuring thickness

Definitions

  • the invention relates to a method of measuring the caliper of a moving web, the method comprising arranging a measuring head on both sides of the web
  • the invention also relates to an apparatus for measuring the caliper of a moving web the apparatus comprising measuring heads arranged on both sides of the web
  • the caliper and other properties of paper and cardboard are typically continuously monitored as the paper is moving Gauges are usually fastened to what is known as a measuring beam, in which the gauges continuously move in a reciprocating manner in the transverse direction of the paper and continuously measure the paper as it moves forward Sensors are arranged as close to the surface of the paper as possible to improve measuring accuracy
  • the contact of the sensors with the irregularities of the surface of the paper may also cause holes to be formed in the paper Conse- quently it is known to use what is known as air bearing, the sensors being provided with a bored hole or holes through which air is blown between the sensor and the paper web Owing to air bearing, the sensor is able to stay clear of the web, and hence e g the irregularities on the surface of the paper do not come
  • US Patent 5,099, 125 discloses a solution for measuring the distance between a radiation source and a radiation sensor arranged on different sides of a web
  • the caliper of the web affecting the distance, is measured in contact with the web, leaving marks on the surface of the paper and causing fouling to the measuring heads
  • each measuring head is provided with an optical distance measuring means for measuring the distance between the measuring head and the surface of the web By subtracting the distances between either measuring head and the web from the distance between the measuring heads allows the caliper of the web to be determined
  • a measuring apparatus comprising a differ- ential coil, comprising at least two coils, and a reference plate, arranged on a first side of the web, and a sensor plate arranged on a second side of the web
  • the voltage generated by the differential coil is proportional to the distance between the reference plate and the sensor plate, whereby the obtained voltage is proportional to the distance between the measuring heads
  • optical distance measuring means are extremely accurate, allowing accurate determination of the caliper of the web
  • the measuring heads can be arranged in the apparatus at a reasonably long distance from the web, where
  • the figure shows an apparatus comprising a first measuring head 1a and a second measuring head 1 b, a web 2 being arranged between them
  • the web 2 is a moving web and can be e g a paper, cardboard or cellulose web the caliper of which is to be measured
  • the web 2 moves in the machine direction in accordance with arrow A
  • the first measuring head 1 a and the second measuring head 1 b are arranged in what is known as a measuring beam 3, in which the measuring heads 1 a and 1 b traverse substantially continuously in a direction transverse with respect to the machine direction
  • the caliper of the web 2 is measured substantially all the time the web 2 moves forward
  • the distance a between the first measuring head 1 a and the second measuring head 1 b is preferably measured by an apparatus comprising a feed coil 4, a differential coil 5 comprising two coils, and a reference plate 6
  • the measuring apparatus further comprises a control device 7 for feeding control current to the feed coil 4
  • the injection frequency of the feed coil is preferably high, i e over 50 kHz, most preferably over 200 kHz
  • the injection frequency is typically about 250 kHz, but may be as high as 500 kHz or more If the injection frequency is high, the number of wire turns of the coils 4 and 5 can be low, resulting in a small and lightweight measuring sensor
  • the feed coil 4 induces to the differential coil circuit a voltage which can be measured by the control device 7 by e g lock-in type of detection
  • the reference plate 6 is arranged on one side of the differential coil 5
  • the gap between the differential coil 5 and the reference plate 6 is substantially con- sta ⁇ t at all times
  • a sensor plate 8 is arranged on the side of the differential coil 5 which is opposite with regard to the reference plate 6
  • the structures of the reference plate 6 and the sensor plate 8 are substantially identical
  • the plates are made from a material which efficiently conducts electricity, e g copper
  • the plate can also comprise merely a conductive metal surface pro- quiz- vaporizing When the material effectively conducts electricity, a thin conductive layer is sufficient A thin conductive layer is sufficient because the higher the injection frequency, the smaller is the current penetration depth inside the conducting body Furthermore, owing to a high injection frequency, the plates 6 and 8 can be made thin and consequently their masses can be kept small
  • the feed coil 4, the differential coil 5 and the reference plate 6 are arranged on the first side of the web 2 and the sensor plate 8 on the second side of the web 2
  • the voltage of the differential coil 7, to be detected by the control device 7 is proportional to the distance d between the reference plate 6 and the sensor plate 8
  • the distance e between the reference plate 6 and the surface of the first measuring head 1 a on the side of the web 2 being a known constant results simply in
  • a is the distance between the first measuring head 1 a and the second measuring head 1 b
  • d is the distance between the reference plate 6 and the sensor plate 8
  • e is the distance between the reference plate 6 and the surface of the first measuring head 1 a on the side of the web 2
  • control device 7 produces a voltage U x , which is proportional to the distance a between the first measuring head 1 a and the second measuring head 1 b
  • the apparatus can be calibrated by samples having a known caliper, whereby the voltage readings obtained can be easily converted into caliper readings
  • the distance b between the first measuring head 1a and the web 2 can be determined extremely accurately by means of a first optical distance measuring means 9a
  • TX denotes a transmitter part in the optical distance measuring means
  • RX denotes a receiver part in the optical distance measuring means
  • Optical distance measuring means are known per se to persons skilled in the art, hence their operation and structure will not be described in any greater detail herein
  • the distance c between the second measuring head 1 b and the web 2 is measured similarly by means of a second optical distance measuring means 9b
  • T is the caliper of the web 2
  • a is the distance between the first measuring head 1 a and the second measuring head 1 b
  • b is the distance between the first measuring head 1 a and the web 2
  • c is the distance between the second measuring head 1 b and the web 2.
  • a control unit 10 is used to control the measuring devices and to perform the necessary calculations.
  • a typical value for the distance a between the first measuring head 1a and the second measuring head 1 b is 6 mm.
  • the distance d between the reference plate 6 and the sensor plate 8 can be e.g. about 20 mm. If the web 2 is very thick, said distances can easily be longer.
  • the final result of the cali- per measured is influenced by the roughness of the surface to be measured.
  • the roughness is a relatively stable phenomenon in measurement of the same web, whereby the roughness can be taken into account e.g. by means of samples by comparing with laboratory measurements.
  • the optical distance measuring means for measuring the distance between the measuring heads may be devices located either outside the coil constructions or inside the coil constructions in accordance with the attached figure. Most preferably the optical distance measuring means are positioned inside the coil constructions, since this minimizes the effect of the disalignment of the surfaces of the measuring heads. There may be several sensors measuring the distance between the measuring heads, allowing also the inclination between the surfaces of the measuring heads to be measured and taken into account when determining the caliper of the web to be measured.
  • the feed coil 4 is not necessary, but electric current may also be fed directly to either part of the differential coil 5 In this case said part of the differential coil 5 would serve as the feed coil 4
  • the structure of the differential coil 5 may comprise more than two coils
  • the differential coil 5 is most preferably symmetric whereby the voltage U x produced by the control device 7 is close to zero at least m e g caliper measurements involving thinner qualities

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Length Measuring Devices With Unspecified Measuring Means (AREA)

Abstract

L'invention concerne un procédé et un appareil de mesure de l'épaisseur d'une bande continue en mouvement. Dans cette invention, on mesure la distance (a) entre des têtes de mesure (1a, 1b) placées des deux côtés de la bande continue (2) en mouvement, et on utilise simultanément des dispositifs de mesure (9a, 9b) de la distance optiques pour mesurer les distances (b, c) entre chaque tête de mesure (1a, 1b) et la surface de la bande continue (2). On détermine l'épaisseur (T) de la bande continue (2) en soustrayant les distances (b, c) entre chacune des têtes de mesure (1a, 1b) et la bande continue (2), de la distance (a) entre les têtes de mesure (1a, 1b).
PCT/FI1999/000148 1998-02-26 1999-02-25 Procede et appareil de mesure de l'epaisseur d'une bande continue en mouvement Ceased WO1999044012A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU26262/99A AU2626299A (en) 1998-02-26 1999-02-25 Method and apparatus for measuring caliper of moving web

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI980444 1998-02-26
FI980444A FI980444A0 (fi) 1998-02-26 1998-02-26 Foerfarande och anordning foer maetning av tjockleken hos en roerlig bana

Publications (1)

Publication Number Publication Date
WO1999044012A1 true WO1999044012A1 (fr) 1999-09-02

Family

ID=8551039

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1999/000148 Ceased WO1999044012A1 (fr) 1998-02-26 1999-02-25 Procede et appareil de mesure de l'epaisseur d'une bande continue en mouvement

Country Status (3)

Country Link
AU (1) AU2626299A (fr)
FI (1) FI980444A0 (fr)
WO (1) WO1999044012A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009138053A1 (fr) * 2008-05-16 2009-11-19 Micro-Epsilon Messtechnik Gmbh & Co. Kg Procédé d’étalonnage d’un appareil servant à mesurer l’épaisseur
WO2011000667A1 (fr) 2009-07-02 2011-01-06 Voith Patent Gmbh Procédé de détermination sans contact de l'épaisseur d'une bande de matériau
WO2011000665A1 (fr) * 2009-07-02 2011-01-06 Voith Patent Gmbh Procédé et dispositif destinés à la détermination sans contact de l'épaisseur d'une bande de matériau avec correction du défaut d'alignement
DE10212382B4 (de) * 2001-03-23 2016-01-28 Omron Corp. Versetzungssensor

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4107606A (en) * 1976-12-14 1978-08-15 Measurex Corporation Non-contacting electromagnetic thickness gauge for sheet measurement having improved small distance sensitivity
US4773760A (en) * 1986-05-14 1988-09-27 Tapio Makkonen Procedure and means for measuring the thickness of a film-like or sheet-like web
EP0500367A2 (fr) * 1991-02-20 1992-08-26 Telkor (Proprietary) Limited Agencement de bobines et dispositif de mesure statique
US5581353A (en) * 1995-02-14 1996-12-03 Qualitek Ltd. Laser-based measurement apparatus and method for the on-line measurement of multiple corrugated board characteristics

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4107606A (en) * 1976-12-14 1978-08-15 Measurex Corporation Non-contacting electromagnetic thickness gauge for sheet measurement having improved small distance sensitivity
US4773760A (en) * 1986-05-14 1988-09-27 Tapio Makkonen Procedure and means for measuring the thickness of a film-like or sheet-like web
EP0500367A2 (fr) * 1991-02-20 1992-08-26 Telkor (Proprietary) Limited Agencement de bobines et dispositif de mesure statique
US5581353A (en) * 1995-02-14 1996-12-03 Qualitek Ltd. Laser-based measurement apparatus and method for the on-line measurement of multiple corrugated board characteristics

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10212382B4 (de) * 2001-03-23 2016-01-28 Omron Corp. Versetzungssensor
WO2009138053A1 (fr) * 2008-05-16 2009-11-19 Micro-Epsilon Messtechnik Gmbh & Co. Kg Procédé d’étalonnage d’un appareil servant à mesurer l’épaisseur
DE102009011122B4 (de) * 2008-05-16 2013-04-11 Micro-Epsilon Messtechnik Gmbh & Co. Kg Verfahren zum Kalibrieren einer Dickenmesseinrichtung
US8554503B2 (en) 2008-05-16 2013-10-08 Micro-Epsilon Messetechnik GmbH Method for calibrating a thickness gauge
WO2011000667A1 (fr) 2009-07-02 2011-01-06 Voith Patent Gmbh Procédé de détermination sans contact de l'épaisseur d'une bande de matériau
WO2011000665A1 (fr) * 2009-07-02 2011-01-06 Voith Patent Gmbh Procédé et dispositif destinés à la détermination sans contact de l'épaisseur d'une bande de matériau avec correction du défaut d'alignement
CN102483321A (zh) * 2009-07-02 2012-05-30 沃依特专利有限责任公司 用于无接触地确定料幅厚度的方法
CN102483322A (zh) * 2009-07-02 2012-05-30 沃依特专利有限责任公司 通过修正定向误差无接触地确定料幅厚度的方法和装置
US9046349B2 (en) 2009-07-02 2015-06-02 Voith Patent Gmbh Method and device for contactless determination of the thickness of a web of material, including correction of the alignment error

Also Published As

Publication number Publication date
AU2626299A (en) 1999-09-15
FI980444A0 (fi) 1998-02-26

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