WO2001075456A1 - A method to measure a movement of an object - Google Patents

A method to measure a movement of an object Download PDF

Info

Publication number
WO2001075456A1
WO2001075456A1 PCT/SE2001/000659 SE0100659W WO0175456A1 WO 2001075456 A1 WO2001075456 A1 WO 2001075456A1 SE 0100659 W SE0100659 W SE 0100659W WO 0175456 A1 WO0175456 A1 WO 0175456A1
Authority
WO
WIPO (PCT)
Prior art keywords
movement
mould
sweeps
sweep
string
Prior art date
Application number
PCT/SE2001/000659
Other languages
French (fr)
Inventor
Thomas Olsson
Original Assignee
Mefos, Stiftelsen För Metallurgisk Forskning
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 Mefos, Stiftelsen För Metallurgisk Forskning filed Critical Mefos, Stiftelsen För Metallurgisk Forskning
Priority to AU2001244944A priority Critical patent/AU2001244944A1/en
Publication of WO2001075456A1 publication Critical patent/WO2001075456A1/en

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
    • G01P3/64—Devices characterised by the determination of the time taken to traverse a fixed distance
    • G01P3/80—Devices characterised by the determination of the time taken to traverse a fixed distance using auto-correlation or cross-correlation detection means
    • G01P3/803—Devices characterised by the determination of the time taken to traverse a fixed distance using auto-correlation or cross-correlation detection means in devices of the type to be classified in G01P3/66
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations
    • 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

  • This invention relates to a method to measure the displacement of an object.
  • the object, the displacement of which is to be measured can for example be the steel string cast in a continuous casting process.
  • an open vertical mould which is oscillated at a frequency that usually is 1-2 Hz.
  • the casting velocity is in the order of 1 m/s and the velocity is usually measured by means of a steel wheel that rolls on the string and has a pulse emitter.
  • the relatively large friction forces between the mould and the string make the oscillation propagate to the string. Sometimes, this oscillation can be observed visually even when casting slabs. Large forces are induced in the cast shell if the friction increases in the mould and the risk of cracking increases. It would be possible to observe such an increased risk as an increased oscillation of the string, but the mechanical measurement cannot register changes in this oscillation.
  • the environment is tough and there is no technique available for measuring the changes in oscillation, which is insensitive to disturbance, long lasting and reliable.
  • This object is fulfilled in accordance with the invention in that in the direction of movement of the object, along the movement or opposite the movement, one sweeps an eddy-current inducer a predetermined distance over a surface of the object with the sweep overlapping the preceding sweep and compares the received signal, that defines the topography of the surface, with the signal in the preceding sweep by means of correlation analysis so as to get the displacement that has occurred between the steps.
  • Figure 1 is a diagram of a device for carrying out the invention.
  • Figure 2 shows a signal from a sweep of an inducer.
  • Figure 3 shows the signal from a preceding sweep.
  • the invention will be described as used for measuring a steel semi, a slab, that is continually cast in a water-cooled mould that is open in both ends.
  • Liquid steel is to the upper end of the mould and the semi that has a solidified shell is continuously vertically drawn out of the mould.
  • the mould is oscillated in its longitudinal direction with a frequency of 1-2 Hz.
  • the semi 11 is shown in figure 1 and its movement is indicated with an arrow.
  • the mould and the arrangement for casting is not illustrated since it is conventional technique of the kind found on international patent class B22D-011/04.
  • Under the mould there is a bow-formed cooling chamber that can be about 10 meter long and it cools the string with water. The string is deviated and it becomes horizontal before it reaches a cutting station.
  • An eddy-current inducer 12 is mounted out of contact with but close to the semi either in the cooling line or after the cooling line.
  • the eddy-current inducer is arranged to sweep a predetermined distance along the semi and back again.
  • the mechanical device for carrying out this movement is not illustrated.
  • the eddy-current inducer 12 is coupled to an electronic box 13 with a control system for the inducer, and the electronic box 13 is coupled to a computer 14, for example an ordinary PC that has a program for the analysis.
  • the inducer 12 and the electronic box 13 are available from commercial companies and is not described.
  • the equipment is conventionally used for crack detection.
  • the inducer 11 When the inducer 11 makes a sweep, it receives a signal that inducer 11 makes a sweep, it receives a signal that represents the surface topography and material properties near the surface, for example inclusions of slag.
  • a signal In figure 1 , an example of a signal is shown that represents the surface topography and material properties. The signal is on the ordinate and the sweep on the abscissa.
  • Figure 3 shows the signal from the preceding sweep.
  • the computer uses common correlation analysis to calculate the distance that the surface, that is the semi 11 , has moved between the two sweeps. Since the time between the sweeps is known, the velocity of the movement can also be calculated. The length of the sweeps and the frequency must be adapted to the intended casting velocity so that there will be a sufficient overlap to provide for an accurate correlation analysis. It is possible to measure in the one direction, either with or opposite to the movement of casting, or to measure in both directions.
  • the sweep frequency is considerably greater than the oscillation frequency of the mould, for example 10 times greater, then possible oscillation superimposed to the oscillation of the mould will also be indicated.
  • Variation in the oscillation of the mould depends on variation in the friction between the mould and the string. Great friction induces forces in the shell of the string, which increases the risk of cracks forming.
  • the eddy- current inducer should be located close to the mould and it can be made robust enough for this environment.
  • the way of measuring is described above with reference to continuous casting, but it can be used also in other processes, for example during the hot rolling of a cast semi.
  • the way of measuring described above is particularly suitable for hard environments.

Landscapes

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

Abstract

One measures the velocity and the displacement of an object, for example casting velocity and casting length in the continuous casting of a steel string (11) in the tough environment. In the direction of movement of the object (11), along the movement or opposite the movement, one sweeps an eddy-current inducer (12) a predetermined distance over a surface of the object with the sweep overlapping the preceding sweep and compares the received signal, that defines the topography of the surface, with the signal in the preceding sweep by means of correlation analysis so as to get the displacement that has occurred between the steps. One gets also a measurement of the friction in the mould by registering variations in the oscillation superimposed to the string as a result of the oscillation of the mould.

Description

A METHOD TO MEASURE A MOVEMENT OF AN OBJECT
Technical field
This invention relates to a method to measure the displacement of an object. The object, the displacement of which is to be measured, can for example be the steel string cast in a continuous casting process.
Background of the invention and prior art
In the continuous casting of steel, an open vertical mould is used which is oscillated at a frequency that usually is 1-2 Hz. The casting velocity is in the order of 1 m/s and the velocity is usually measured by means of a steel wheel that rolls on the string and has a pulse emitter. The relatively large friction forces between the mould and the string make the oscillation propagate to the string. Sometimes, this oscillation can be observed visually even when casting slabs. Large forces are induced in the cast shell if the friction increases in the mould and the risk of cracking increases. It would be possible to observe such an increased risk as an increased oscillation of the string, but the mechanical measurement cannot register changes in this oscillation. The environment is tough and there is no technique available for measuring the changes in oscillation, which is insensitive to disturbance, long lasting and reliable.
Object of invention and short description of the invention
It is an object of the invention to provide a method of measuring with great accurateness and reliability the displacement of an object also in a tough environment. This object is fulfilled in accordance with the invention in that in the direction of movement of the object, along the movement or opposite the movement, one sweeps an eddy-current inducer a predetermined distance over a surface of the object with the sweep overlapping the preceding sweep and compares the received signal, that defines the topography of the surface, with the signal in the preceding sweep by means of correlation analysis so as to get the displacement that has occurred between the steps. Brief description of the figures and detailed description of the invention
• Figure 1 is a diagram of a device for carrying out the invention.
• Figure 2 shows a signal from a sweep of an inducer.
• Figure 3 shows the signal from a preceding sweep.
The invention will be described as used for measuring a steel semi, a slab, that is continually cast in a water-cooled mould that is open in both ends. Liquid steel is to the upper end of the mould and the semi that has a solidified shell is continuously vertically drawn out of the mould. The mould is oscillated in its longitudinal direction with a frequency of 1-2 Hz. The semi 11 is shown in figure 1 and its movement is indicated with an arrow. The mould and the arrangement for casting is not illustrated since it is conventional technique of the kind found on international patent class B22D-011/04. Under the mould, there is a bow-formed cooling chamber that can be about 10 meter long and it cools the string with water. The string is deviated and it becomes horizontal before it reaches a cutting station. An eddy-current inducer 12 is mounted out of contact with but close to the semi either in the cooling line or after the cooling line. The eddy-current inducer is arranged to sweep a predetermined distance along the semi and back again. The mechanical device for carrying out this movement is not illustrated. Alternatively to having a mechanical movement, one can have an inducer that is mechanically immobile but has a sweeping magnetic field; in both cases, it can be considered that the inducer sweeps. The eddy-current inducer 12 is coupled to an electronic box 13 with a control system for the inducer, and the electronic box 13 is coupled to a computer 14, for example an ordinary PC that has a program for the analysis. The inducer 12 and the electronic box 13 are available from commercial companies and is not described. The equipment is conventionally used for crack detection.
When the inducer 11 makes a sweep, it receives a signal that inducer 11 makes a sweep, it receives a signal that represents the surface topography and material properties near the surface, for example inclusions of slag. In figure 1 , an example of a signal is shown that represents the surface topography and material properties. The signal is on the ordinate and the sweep on the abscissa. Figure 3 shows the signal from the preceding sweep. The computer uses common correlation analysis to calculate the distance that the surface, that is the semi 11 , has moved between the two sweeps. Since the time between the sweeps is known, the velocity of the movement can also be calculated. The length of the sweeps and the frequency must be adapted to the intended casting velocity so that there will be a sufficient overlap to provide for an accurate correlation analysis. It is possible to measure in the one direction, either with or opposite to the movement of casting, or to measure in both directions.
If the sweep frequency is considerably greater than the oscillation frequency of the mould, for example 10 times greater, then possible oscillation superimposed to the oscillation of the mould will also be indicated. Variation in the oscillation of the mould depends on variation in the friction between the mould and the string. Great friction induces forces in the shell of the string, which increases the risk of cracks forming. Thus, by the described measuring and a simple computer program, it will be possible to predict the risk of cracking, which is of utmost importance for the quality assurance and which can save large costs in later production steps, in particular in the rolling. In order to get as accurate a measurement of the oscillation as possible, the eddy- current inducer should be located close to the mould and it can be made robust enough for this environment.
The way of measuring is described above with reference to continuous casting, but it can be used also in other processes, for example during the hot rolling of a cast semi. The way of measuring described above is particularly suitable for hard environments.

Claims

Claims
1. A method of measuring a movement of an object (11), characterised in that in the direction of movement of the object (11), along the movement or opposite the movement, one sweeps an eddy-current inducer (12) a predetermined distance over a surface of the object with the sweep overlapping the preceding sweep and compares the received signal, that defines the topography of the surface, with the signal in the preceding sweep by means of correlation analysis so as to get the displacement that has occurred between the steps.
2. A method according to claim 1 , characterised in that one adapts the frequency of the sweeps and the length of the sweeps to the movement of the object (11) so that the sweeps overlap at least 50%.
3. A method according to any one of the preceding claims, characterised in that one measures the displacement of an object (11) that has a movement with superimposed oscillation and sweeps with a frequency that is at least 5 times the oscillation frequency.
4. A method according to any one of the preceding claims, characterised in that one measures the casting velocity during continuous casting of metal in an open ended mould by sweeping the eddy-current inducer (12) over the string (12) that exits the mould.
5. A method according to claim 4, characterised in that one carries out the sweeping over the string (12) inside a cooling chamber below the mould.
PCT/SE2001/000659 2000-03-27 2001-03-26 A method to measure a movement of an object WO2001075456A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001244944A AU2001244944A1 (en) 2000-03-27 2001-03-26 A method to measure a movement of an object

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0001060-3 2000-03-27
SE0001060A SE516072C2 (en) 2000-03-27 2000-03-27 Ways of measuring the movement of an object by means of a whirlpool sensor

Publications (1)

Publication Number Publication Date
WO2001075456A1 true WO2001075456A1 (en) 2001-10-11

Family

ID=20279012

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE2001/000659 WO2001075456A1 (en) 2000-03-27 2001-03-26 A method to measure a movement of an object

Country Status (3)

Country Link
AU (1) AU2001244944A1 (en)
SE (1) SE516072C2 (en)
WO (1) WO2001075456A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012107006A1 (en) * 2011-02-09 2012-08-16 Balluff Gmbh Method for detecting the torsion angle of a shaft and/or of a torque occurring on the shaft and implementation of the method

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4767986A (en) * 1985-11-25 1988-08-30 Toernblom Bengt H Oscillating transducers for monitoring the surface of elongated objects
DE4014756A1 (en) * 1990-05-08 1991-11-21 Cenith Systems Gmbh & Co Kg Movement detection device for object or material e.g. of metal - has eddy current generator and correlator of structure noise signal

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4767986A (en) * 1985-11-25 1988-08-30 Toernblom Bengt H Oscillating transducers for monitoring the surface of elongated objects
DE4014756A1 (en) * 1990-05-08 1991-11-21 Cenith Systems Gmbh & Co Kg Movement detection device for object or material e.g. of metal - has eddy current generator and correlator of structure noise signal

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012107006A1 (en) * 2011-02-09 2012-08-16 Balluff Gmbh Method for detecting the torsion angle of a shaft and/or of a torque occurring on the shaft and implementation of the method

Also Published As

Publication number Publication date
SE0001060D0 (en) 2000-03-27
AU2001244944A1 (en) 2001-10-15
SE0001060L (en) 2001-09-28
SE516072C2 (en) 2001-11-12

Similar Documents

Publication Publication Date Title
JP3386051B2 (en) Method for estimating flow pattern of molten steel in continuous casting, temperature measuring device for mold copper plate, method for determining surface defects of continuous cast slab, method for detecting molten steel flow, method for evaluating non-uniformity of heat removal in mold, method for controlling molten steel flow, Quality control method in continuous casting, continuous casting method of steel, estimation method of molten steel flow velocity
US4534405A (en) Method and an arrangement for inspecting the surface of steel stock having a temperature above the Curie point
US5781008A (en) Instantaneous slag thickness measuring device
JPS61502012A (en) Method for detecting and recording defects in hot semi-finished steel products
JP4105839B2 (en) In-mold casting abnormality detection method in continuous casting
EP0554895B1 (en) Method and apparatus for detecting thickness of and penetrant metal in refractories lined in a vessel for molten metal
JP3230513B2 (en) Method of estimating molten steel flow velocity in continuous casting mold, quality control method in continuous casting of steel, and continuous casting method of steel
WO2001075456A1 (en) A method to measure a movement of an object
JP4842195B2 (en) Slab surface temperature measuring device and slab surface temperature measuring method
Jenkins et al. Investigation of Strand surface defects using Mold instrumentation and Modelling
Ozgu Continuous caster instrumentation: State-of-the-art review
JP3757830B2 (en) Manufacturing method of continuous cast slab
Mazza et al. The mold temperature mapping with ultrasonic contactless technology is the key for the real-time initial solidification process control tools
JP4483538B2 (en) Method and device for detecting solidification completion position of continuous cast slab and method for producing continuous cast slab
JP3537625B2 (en) Method and apparatus for measuring solidified shell thickness in continuous casting
JPH04284956A (en) Method for continuously casting steel
JPH04262841A (en) Instrument and method for measuring flow speed on surface of molten steel in continuous casting mold
JP4453558B2 (en) Quality judgment method for continuous cast slabs
JPH07268428A (en) Structure for side wall part of furnace bottom in blast furnace and method for measuring remaining thickness of furnace bottom brick
JPH0263652A (en) Method of determining molten metal pond in double belt type continuous casting device
KR20010045770A (en) Soft reduction method of continuous casting slab
JP4296946B2 (en) Method and device for detecting solidification completion position of continuous cast slab
KR100761575B1 (en) Detection of roller damage and/or misalignment in continuous casting of metals
JP4414609B2 (en) Method and apparatus for detecting drift in molten steel in continuous casting of steel
JP3252770B2 (en) Detecting method and control method of molten metal level in continuous casting

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CR CU CZ DE DK DM DZ EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG US UZ VN YU ZA ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: JP