EP0302099A1 - Appareil permettant de mesurer ou de tester la dimension ou le contour en mesurant la distance - Google Patents

Appareil permettant de mesurer ou de tester la dimension ou le contour en mesurant la distance

Info

Publication number
EP0302099A1
EP0302099A1 EP19880901956 EP88901956A EP0302099A1 EP 0302099 A1 EP0302099 A1 EP 0302099A1 EP 19880901956 EP19880901956 EP 19880901956 EP 88901956 A EP88901956 A EP 88901956A EP 0302099 A1 EP0302099 A1 EP 0302099A1
Authority
EP
European Patent Office
Prior art keywords
transducer
test object
distance
transducers
measured
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
EP19880901956
Other languages
German (de)
English (en)
Inventor
Bengt Hjalmar Törnblom
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.)
Individual
Original Assignee
Individual
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 Individual filed Critical Individual
Publication of EP0302099A1 publication Critical patent/EP0302099A1/fr
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
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/12—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring diameters
    • G01B7/125—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring diameters 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
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/28—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring contours or curvatures

Definitions

  • Apparatus for measuring or testing dimension or contour through measuring distance
  • the present invention shall be deemed a device and relates to the field of measuring and/or testing, more particularly in the field of eddy-current technique.
  • the invention shows how test objects can be measured and/or tested, e.g. detected, with respect to a quantity where said quantity may, for instance, be the dimension of a hot-rolled wire during the rolling processing.
  • the present invention based on the use of currents with associated magnetic fields induced in the test object, shows how the problems described here, and other associated problems, can be solved.
  • the lift-signal is instead used, or better lift-off vector, to measure the distance between transducer and test object.
  • Swedish patent applications 8302738-3 and 8400698-0 described, with the aid of impedance diagrams, how the impedance of the transducer is affected by the lift-off distance (LO).
  • the LO-signal is used to control transformation and amplification of the crack signal.
  • several surface transducers are placed e.g. round a rolled wire as shown in Figure 1, and simultaneously measure the distance to the wire (1).
  • Each transducer (2) may be said to correspond to one reference point (RP), as indicated in Figure 2.
  • FIG. 1 of the drawings shows transducers (2) with surface transducer coils (4).
  • the transducers are, for instance, arranged symmetrically around the test object (1), the cross section of the test object being shown.
  • the transducers are connected to an electronics device (3).
  • Figure 3 thus shows the signal (V) which is obtained indirectly from the transducer as a function of LO.
  • the LO function curve will asymtotically approach zero with increasing LO.
  • the signal V in Figure 3 deriving from the transducer, indirectly corresponds to the distance LO in Figure 1.
  • a linear function according to Figure 4 can be obtained, where LO can correspond to the actual LO distance in Figure 2. This linear function is of course easier to utilize than the non-linear exponential function in Figure 3.
  • the function according to Figure 4 need not necessary show the distance LO between transducer and test object but, if preferred, may show the distance LO to a reference position pertaining to the transducer, designated reference point (RP).
  • the reference points of the transducers are marked in Figure 2, as well as their distance LO to the test object (1).
  • the diameter of the test object is designated D.
  • the distance between two diametrically located reference points is designated A.
  • the reference point RP need not be a point in the transducer but may be a fictive, imagined point at a distance LO from the surface of the test object.
  • RP is the point or the like at which the part-function describing the distance to the test object of its surface is equal to zero.
  • This function can be represented by either signals or digital measured values, etc.
  • the reference point always refers to the relevant transducer in so much as it is a function, direct or indirect, of the position of the transducer.
  • the reference point is an imagined aid to facilitate calculating a quantity.
  • Figure 5 is an example of what is meant by reference point since D has been calculated from the distance between the reference points RP 1 and RP 2 .
  • This calculation can of course be performed using either hardware or software, e.g. via programmable electronics such as computers or the like.
  • the compensation may be performed at some other LO if suitable.
  • Computer refers for instance to the type of compensation, including balancing, described in Swedish patent applications 7507857-6, 7613708-2, 7813344-4, 8302738-3 and 8400698-0 and the terminology used is substantially covered by the present invention.
  • the electronics, part (3) in Figure 1 may be conventionally constructed with respect to the eddy-current part.
  • a good example of how the eddy-current part can be designed is revealed in Swedish patent application 8400698-0 in which Figure 3 exactly describes one of many feasible examples of what item 3 in Figure 1 may include.
  • the output signal from the eddy-current part can then be further signal-processed, for instance, via associated analog-digital convertors and computer including the calculation part (4).
  • the distance (A) between the reference points, RP must be as exact and stable as possible.
  • the transducers must often be compensated immediately before the leading end of the wire passes in through the transducer arrangement. All previous functions such as temperature-dependent winding resistors and the like are then eliminated. It is thus advisable to provide a photocell to sense the wire immediately before the transducers and to give this photocell as compensation pulse during which the transducers are rapidly compensated. Thereafter, e.g. after 10 ms, the wire may entire the new transducer arrangement. The performance of the device is thus always at its highest before measurement.
  • the throughput channel of the transducer can be varied automatically, for instance. This may be valuable as it allows the transducer opening to be made temporarily large enough to prevent ribs, etc., at the leading end of the wire from becoming wedged in the transducer.
  • Transit transducers may be used instead of surface transducers, or a combination of surface and transit transducers.
  • the surface transducers in Figure 1 may also be provided with automatic distance setters, e.g. ball-bearing screws and motors, which can set the transducers at predetermined LO-distances to suit the dimension of the wire currently being tested, for instance.
  • automatic distance setters e.g. ball-bearing screws and motors, which can set the transducers at predetermined LO-distances to suit the dimension of the wire currently being tested, for instance.
  • a special calculating function may then be provided for each such distance setter.
  • the computer memory/program is then suitably provided with a library of suitable functions, including correction programs for relevant wire dimensions and so on.
  • LO distance
  • a relatively large working area e.g.1-10 mm. It is therefore suitable to provide the surface transducers with ferrite cores, for instance, which amplify the magnetic flow between transducer and test object.
  • This problem can also be overcome by correcting the measurement with the aid of the deviation of the wire from a normal position such as P1 in Figure 1.
  • the dimension of the wire is thus also calculated as a function of the position of the test object, e.g. its centering in relation to the transducers, and thus taking this into account.
  • An excellent method of determining the position of the wire is to utilize the transducers as described in Swedish patent 8101284-1. The transducers can then be used to measure both the dimension and the position of the wire on the basis of two different devices/principles. Furthermore, there is nothing to prevent the same transducer also being used for crack detection, for instance, in which case the application will be more complete and sophisticated.
  • a surface crack (5) has been drawn in by way of example in Figure 2.
  • This surface crack disturbs the spread of the eddy currents induced on the surface of the test object, which in turn is understood by the surface transducer coil as a change in impedance.
  • This change in impedance can be described as a vector (refer to Patent application 8302738-3 for instance), the direction of which usually substantially coincides with the distance direction, LO, in the impedance plane of the transducer. This may cause the transducer to believe that the surface of the test object is further away than it really is and the dimension calculation is disturbed by the crack, with the result that it is generally incorrect.
  • vector transformation technique based on the use of several carrier frequencies can be used.
  • Swedish patent application 8700359-6 describes how a transformation device excellent for this purpose can be designed and used.
  • This vector transformation thus enables those variables/parameters which disturb the dimension measurement, for instance, to be separated out, thus avoiding presentation of incorrect dimension values.
  • Another related problem is temperature influence of various kinds on the measurement.
  • the temperature varies after compensation, the inner resistance of the transducer coils, as well as the resistance over-transformed from the metallic transducer casing. These resistance fluctuations cause various types of disturbances.
  • One method of avoiding these is to control the temperature of the coolant to the transducers, another is to correct the measured values on the basis of the temperature fluctuations measured.
  • Undesired measuring effects caused by varying temperatures in the test object can also be suppressed in similar manner.
  • a varying alloy composition in the test object can, for instance, produce similar effects to those obtained from a variation in temperature. This is because both influence the electrical conductivity of the test object. Since the alloy composition is generally known and the temperature of the wire can be measured, the signals required to correct the calculation functions for the quantity are available.
  • the invention is intended for use in measuring the dimension of hot rolled wire and the like where the test object has a temperature above its Curie point.
  • the material is then non-magnetic.
  • the invention is also suitable for measuring/testing cold materials, both magnetic and non-magnetic.
  • the invention can be used to measure quantities such as the level of a steel melt, etc. If the LO distance is calculated directly from the non-linear function in Figure 3, via a mathematicaly model/algorithm, for instance, this can be considered a linearization since a type of function conversion is used based on at least one real or fictive reference point. This therefore also falls within the scope of the invention.
  • the wire diameter for instance, is changed when the final product is changed.
  • Fine adjustment of the functions controlling, for instance by computer program the correction/compensation of e.g. the influence of deviations from the centre, must therefore be performed. It may therefore be advisable to have a small series of "standards" of various diameters, these being placed one by one in the measuring position in the transductor for the computer to store the relevant measured values.
  • the computer then suitably calculates the functions describing the influence of the different variables on the measured result, i.e. quantity, and can then also generate suitable and optimum correction functions.
  • Calibration standards can of course also be automatically inserted into the transducer by mechanical means on suitable occasions.
  • a calibration standard might consist, for instance, of a shaft which is turned in steps so that it has different diameters in axial direction.
  • the shaft material is suitably non-magnetic steel with the same electrical properties as the test object.
  • the transducer arrangement according to Figure 1 can advantageously be secured in a guide tube immediately after the roller stand in a wire rolling mill.
  • the transducers thus move relative to the rolled wire due to the movement of the wire.
  • the invention also includes applications in which the transducers rotate or oscillate around the test object.
  • the invention also includes all imaginable forms of test object. Particularly in rolling mills it may be of great importance to measure the dimension of the rolled wire after each reduction step so that the rolling process and its parameters can be controlled and corrected on the basis of information as to the diameter of the wire.
  • Another interesting application for the invention is measuring flatness, e.g. of steel strip and the like.
  • Figure 7 is provided to give a clearer view of this and should be considered as a comprehensive figure shown in principle the variables normally included in the calculation of a quantity, such as dimension.
  • test object (1) is surrounded by the surface transducer coils of the transducer arrangement (2) connected to the electronics system (3) which is in turn connection to the calculating part (4) in which the quantity (ST) is calculated.
  • the measuring and calculating parts may be included in the same electronic unit.
  • N Lift-off function values e.g. in accordance with Figure 3 M2
  • Transducer position e.g. LO position in other words
  • a Other signals transmitted to the calculating part (4) are, for instance:
  • the quantity is calculated with the aid of these input signals.
  • the calculating unit (4) may suitably include a microcomputer with a hardware-based calculating modules for quick calculation. Combining the invention with the devices described in Swedish patent application 8700472-7 offers the advantage that the electronics part (3) and calculating part (4) can be common for a number of transducers and/or transducer arrangements.
  • test objects may be billets, rods, wire, pipes, sheet-metal, molten metal, etc.
  • the transducer may be eddy-current based surface transducers, Hall-elements, various types of sensors, etc., or combinations thereof.
  • the quantity may be dimension, form, position, profile, temperature, speed, etc., or combinations thereof. "Quantity" is thus a broad concept.
  • Carrier frequency may be the frequency of the relevant eddy current or frequency components included therein.
  • LO may be what is normally termed lift-off. Examples of this are given in Swedish patent applications 8400689-0 and 8400861-4, for instance.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)

Abstract

Dispositif permettant de tester et/ou de mesurer quantitativement des objets soumis à essai tels qu'un fil-machine (1), par exemple la dimension, la forme, etc. L'invention illustre comment la grandeur peut être calculée via une procédure inverse de mesure de distance. En mesurant la distance entre la surface de l'objet soumis à essai, ou une partie de celui-ci, et des points de référence (RP), souvent fictifs, appartenant à/servant de référence au transducteur de courant parasite, une grandeur telle que le diamètre (D) peut être calculée/mesurée, étant donné que la distance (A), entre par exemple, des points de référence situés diamètralement, ou analogue, est connue. En combinant l'invention avec un dispositif détecteur de fissure, on peut, par exemple, utiliser le même agencement transducteur pour détecter les fissures et la dimension.
EP19880901956 1987-02-18 1988-02-11 Appareil permettant de mesurer ou de tester la dimension ou le contour en mesurant la distance Ceased EP0302099A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8700659 1987-02-18
SE8700659A SE456606B (sv) 1987-02-18 1987-02-18 Anordning for metning och/eller provning av dimension och/eller form via avstandsmetning

Publications (1)

Publication Number Publication Date
EP0302099A1 true EP0302099A1 (fr) 1989-02-08

Family

ID=20367571

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19880901956 Ceased EP0302099A1 (fr) 1987-02-18 1988-02-11 Appareil permettant de mesurer ou de tester la dimension ou le contour en mesurant la distance

Country Status (3)

Country Link
EP (1) EP0302099A1 (fr)
SE (1) SE456606B (fr)
WO (1) WO1988006268A1 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DK76293D0 (da) * 1993-06-25 1993-06-25 Brueel & Kjaer As Forskydningstransducer
JP4079127B2 (ja) 2004-07-01 2008-04-23 セイコーエプソン株式会社 検査装置及び液滴吐出検査方法
ITUB20153029A1 (it) * 2015-08-10 2017-02-10 Danieli Automation Spa Metodo per la misura a caldo, durante la laminazione, di una dimensione di profili metallici
ITUB20153041A1 (it) * 2015-08-10 2017-02-10 Danieli Automation Spa Dispositivo per la misura a caldo, durante la laminazione, di una dimensione di profili metallici
RU2686520C1 (ru) * 2018-07-26 2019-04-29 Федеральное государственное автономное образовательное учреждение высшего образования "Национальный исследовательский Томский политехнический университет" Способ вихретокового контроля внутреннего диаметра металлических труб
CN113984887B (zh) * 2021-10-29 2024-02-09 中国航发北京航空材料研究院 一种利用涡流自动检测系统在线获取盘件轮廓的方法

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1475517A (en) * 1974-06-27 1977-06-01 British Steel Corp Detection of surface defects in elongate metallic members
US4160204A (en) * 1974-11-11 1979-07-03 Kaman Sciences Corporation Non-contact distance measurement system
JPS5612502A (en) * 1979-07-12 1981-02-06 Nippon Kokan Kk <Nkk> Feedback amplification type vortex flow range finder

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8806268A1 *

Also Published As

Publication number Publication date
SE8700659D0 (sv) 1987-02-18
SE8700659L (sv) 1988-08-19
SE456606B (sv) 1988-10-17
WO1988006268A1 (fr) 1988-08-25

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