WO2002093107A1 - Appareil servant a mesurer l'epaisseur de lignes de coupe - Google Patents

Appareil servant a mesurer l'epaisseur de lignes de coupe Download PDF

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Publication number
WO2002093107A1
WO2002093107A1 PCT/GB2002/002188 GB0202188W WO02093107A1 WO 2002093107 A1 WO2002093107 A1 WO 2002093107A1 GB 0202188 W GB0202188 W GB 0202188W WO 02093107 A1 WO02093107 A1 WO 02093107A1
Authority
WO
WIPO (PCT)
Prior art keywords
measuring means
score line
measuring
conoscope
thickness
Prior art date
Application number
PCT/GB2002/002188
Other languages
English (en)
Inventor
Paul Craddock
Original Assignee
Sencon (Uk) Limited
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 Sencon (Uk) Limited filed Critical Sencon (Uk) Limited
Publication of WO2002093107A1 publication Critical patent/WO2002093107A1/fr

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
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/04—Processes or apparatus for producing holograms
    • G03H1/0493—Special holograms not otherwise provided for, e.g. conoscopic, referenceless holography

Definitions

  • This invention relates to apparatus for measuring residual thickness of metal beneath a score line provided in a metal can end for facilitating opening of the can, such as by a ring pull device or the like.
  • Metal cans such as for food and drink storage, are well known having metal can ends which are scored in order to provide a line of weakness to enable the end of the can, or a portion thereof, to be torn away by a ring pull device, or the like, to gain access to the contents of the can.
  • the provision of a score line locally reduces the thickness of metal of the can end and the residual thickness of metal, known as the score residual, must be accurately controlled. If the residual thickness of metal is too great, the ring pull device is likely to be pulled from the can end without the can being opened. If the residual thickness is too small, leakage of the contents of the can may occur at the score line.
  • United States Patent No. 4 891 529 describes a can top measuring system in which a video camera is used to scan a metal can end, during a manufacturing process, to provide electronic signals representing an image of the can end.
  • a score line residual thickness in the can end is determined by means of a pair of laser range finders located above and below the can end and providing obliquely directed light beams of finite width against opposite major faces of the can end.
  • this system has been found to be unsatisfactory because the laser beams create spurious reflections off the side walls of the score which give rise to interference and erroneous readings.
  • apparatus for measuring residual thickness of metal beneath a score line provided in a metal can end for facilitating opening of the can comprising a carrier means for supporting the can end and first and second measuring means of known distance apart arranged to be on opposite sides of the can end, wherein at least the first measuring means comprises a conoscope adapted to direct a beam of radiation at that surface of the can end provided with the score line at a location of the score line whereby the residual thickness can be determined.
  • the second measuring means may comprise a linear voltage differential transducer, a contacting probe, or laser triangulation distance measuring means.
  • the second measuring means may comprise a conoscope.
  • the first and second measuring means may be arranged to emit substantially coaxial beams of radiation at opposite surfaces of the can end.
  • the carrier means may be provided with an aperture for receiving the can end.
  • the carrier means may be arranged for traversal relative to the first and second measuring means. Such traversal may be in orthogonal directions in a plane of a major face of the can end.
  • the first and second measuring means may be mounted on an arm having a substantial C-shape.
  • the arm may be of aluminium.
  • Such calibration means may comprise a slip gauge which may be in the form of a small sheet of material of known thickness arranged in an aperture in the carrier means and locatable between the first and second measuring means.
  • the score line in the metal can end may be associated with a ring pull device for opening the can.
  • a conoscope is a polarising microscope designed to produce an interferogram of an object.
  • the technique is known as conoscopic holography and is described, for example, in International Patent Publication No. WO 99/42908.
  • an interference pattern is formed between an object beam and a reference beam using a coherent light source, such as a laser.
  • the two beams propagate with the same velocity, but follow separate geometrical paths, creating what is known as a Gabor Zone Lens and an interference pattern.
  • a linear conoscope produces an interferogram of the three-dimensional structure of an object.
  • the interference pattern of the interferogram varies linearly with the distance from the centre of the Gabor Zone Lens.
  • a conoscope system may comprise a birefringent crystal inserted between two circular polarizers.
  • Figure 1 is a side view of an embodiment of apparatus according to the present invention for measuring residual thickness of metal beneath a score line provided in a metal can end;
  • Figure 2 is a plan view of carrier means supporting a can end, for use in the apparatus of Figure 1.
  • Apparatus 2 is arranged for measuring residual thickness of metal beneath a score line 4 ( Figure 2) provided in a metal can end 6 for facilitating opening of a can to which the can end 6 would normally be attached.
  • the can end 6 has a ring pull device 8 which is arranged to remove a portion 10 of the can end 6 enclosed by the score line 4.
  • the can end 6 is located in an aperture 12 provided in a plate-like carrier 14.
  • the first measuring means comprises a conoscope which is directed at that side of the can end 6 provided with the score line 4, while the second measuring means may comprise any suitable measuring means such as a linear voltage differential transducer (LVDT) , a contacting probe, in which a measuring member is mounted within a tubular member for relative movement, or a laser triangulation distance measuring sensor.
  • LVDT linear voltage differential transducer
  • the second measuring means may comprise a further conoscope and for convenience the following description refers more specifically to the use of two conoscopes.
  • the conoscopes 18 and 20 are arranged to face each other at a known, fixed distance apart and are coaxial with each other.
  • the conoscopes 18, 20 are of well known form per se and are commercially available from a number of sources. The construction and operation of such a conoscope is described in WO 99/42908.
  • the carrier 14, with the can end 6 accommodated in the aperture 12 therein is arranged for traversal between the conoscopes 18 and 20.
  • Such traversal is suitably in orthogonal directions, as indicated by arrows 26, 28, in a plane of a major face of the can end.
  • the conoscope 18 is arranged to direct a beam 30 of laser radiation towards the carrier 14 and the conoscope 20 is arranged to direct a beam 32 of laser radiation towards the carrier 14.
  • the two beams 30 and 32 are aligned so as to be substantially coaxial.
  • the carrier 14 is positioned such that the score line 4 on the can end 6 is scanned by the conoscope 18 while the underside of the can end 6, directly underlying each location of the score line 4 scanned by the conoscope 18, is scanned by the conoscope 20.
  • the conoscope 18 provides optical interference data relating to the distance of the upper surface of the can end from the conoscope 18, while the conoscope 20 similarly monitors the underside of the can end 6 and provides data relating to the distance of the lower surface from the conoscope 20. From the data acquired by the two conoscopes and because the two instruments are coaxial and of known distance apart, the distance between the upper and lower surfaces of the can end can readily be determined. Thus the surface and thickness profiles for the can end can be determined by moving the can end relative to the axis of the two conoscopes and, when the conoscopes are directed at the score line, the residual thickness of metal of the can end beneath the score line 4 can readily be determined and indicated as desired.
  • the arm arrangement 16 supporting the conoscopes 18 and 20 is made of a metal such as aluminium, changes in ambient temperature will result in expansion and contraction thereof. This means that the supposedly fixed distance between the conoscopes 18 and 20 may vary and introduce a possibility of errors in the determination of the thickness profile of the can end, and thus of the residual thickness of metal beneath the score line 4 in the can end 6. Such errors could be significant, particularly since measurements to an accuracy of about 1 micron are required in the determination of the residual thickness.
  • a slip gauge 34 is provided on the carrier 14 and comprises a small sheet of material of known thickness arranged in an aperture 36 provided in the carrier 14.
  • the carrier 14 is positioned with the slip gauge 34 between the conoscopes 18 and 20 and with the laser beams 30 and 32 directed on opposite sides of the slip gauge 34.
  • the value of thickness of the slip gauge 34 is determined in the same manner as for the thickness of the can end and is compared with the known thickness value and if found to be different, re- calibration of the apparatus is effected.
  • an automatic system may be provided for storage and transfer of can ends to be tested by the apparatus.
  • Such automatic system may be of rotary form.
  • the apparatus of the invention may also be used to measure dimensions of other parts of the can end.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

Cette invention se rapporte à un appareil servant à mesurer l'épaisseur résiduelle de métal sous une ligne de coupe (4) ménagée dans l'extrémité (6) d'une boîte métallique, en vue de faciliter l'ouverture de cette boîte. Cet appareil comprend un moyen de support (14) servant à soutenir l'extrémité de la boîte et des premier et second moyens de mesure (18, 20) placés à une distance connue l'un de l'autre, de façon à être situés sur des côtés opposés de l'extrémité de la boîte. Au moins le premier moyen de mesure (18) comprend un conoscope destiné à diriger un faisceau de rayonnement sur la surface de l'extrémité (6) de la boîte comportant la ligne de coupe (4), en un endroit de la ligne de coupe où l'épaisseur résiduelle peut être déterminée.
PCT/GB2002/002188 2001-05-14 2002-05-13 Appareil servant a mesurer l'epaisseur de lignes de coupe WO2002093107A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0111674A GB0111674D0 (en) 2001-05-14 2001-05-14 Measuring apparatus
GB0111674.8 2001-05-14

Publications (1)

Publication Number Publication Date
WO2002093107A1 true WO2002093107A1 (fr) 2002-11-21

Family

ID=9914546

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2002/002188 WO2002093107A1 (fr) 2001-05-14 2002-05-13 Appareil servant a mesurer l'epaisseur de lignes de coupe

Country Status (2)

Country Link
GB (1) GB0111674D0 (fr)
WO (1) WO2002093107A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4891529A (en) * 1988-08-22 1990-01-02 View Engineering, Inc. System and method for analyzing dimensions of can tops during manufacture
US5485082A (en) * 1990-04-11 1996-01-16 Micro-Epsilon Messtechnik Gmbh & Co. Kg Method of calibrating a thickness measuring device and device for measuring or monitoring the thickness of layers, tapes, foils, and the like
US5883356A (en) * 1996-05-13 1999-03-16 Tip Engineering Group, Inc. Laser scoring process and apparatus
WO2000042383A1 (fr) * 1999-01-12 2000-07-20 Ipec Precision, Inc. Calibre d'epaisseur sans contact
US6134013A (en) * 1997-09-15 2000-10-17 Optimet, Optical Metrology Ltd. Optical ball grid array inspection system
WO2001070445A1 (fr) * 2000-03-17 2001-09-27 Tip Engineering Group, Inc. Procede et appareil permettant de fragiliser une garniture d'automobile destinee a former une ouverture pour le deploiement d'un coussin de securite gonflable

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4891529A (en) * 1988-08-22 1990-01-02 View Engineering, Inc. System and method for analyzing dimensions of can tops during manufacture
US5485082A (en) * 1990-04-11 1996-01-16 Micro-Epsilon Messtechnik Gmbh & Co. Kg Method of calibrating a thickness measuring device and device for measuring or monitoring the thickness of layers, tapes, foils, and the like
US5883356A (en) * 1996-05-13 1999-03-16 Tip Engineering Group, Inc. Laser scoring process and apparatus
US6134013A (en) * 1997-09-15 2000-10-17 Optimet, Optical Metrology Ltd. Optical ball grid array inspection system
WO2000042383A1 (fr) * 1999-01-12 2000-07-20 Ipec Precision, Inc. Calibre d'epaisseur sans contact
WO2001070445A1 (fr) * 2000-03-17 2001-09-27 Tip Engineering Group, Inc. Procede et appareil permettant de fragiliser une garniture d'automobile destinee a former une ouverture pour le deploiement d'un coussin de securite gonflable

Also Published As

Publication number Publication date
GB0111674D0 (en) 2001-07-04

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