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WO1996031767A1 - Dispositif de controle automatique de particules magnetiques - Google Patents

Dispositif de controle automatique de particules magnetiques Download PDF

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Publication number
WO1996031767A1
WO1996031767A1 PCT/SE1996/000444 SE9600444W WO9631767A1 WO 1996031767 A1 WO1996031767 A1 WO 1996031767A1 SE 9600444 W SE9600444 W SE 9600444W WO 9631767 A1 WO9631767 A1 WO 9631767A1
Authority
WO
WIPO (PCT)
Prior art keywords
light
sample
ray
path
reflected
Prior art date
Application number
PCT/SE1996/000444
Other languages
English (en)
Inventor
Karl-Gunnar Bergstrand
Original Assignee
Contest Marketing Ab
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 Contest Marketing Ab filed Critical Contest Marketing Ab
Priority to AU52941/96A priority Critical patent/AU5294196A/en
Priority to EP96909458A priority patent/EP0819245A1/fr
Publication of WO1996031767A1 publication Critical patent/WO1996031767A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G01N21/956—Inspecting patterns on the surface of objects
    • G01N21/95623—Inspecting patterns on the surface of objects using a spatial filtering method
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
    • G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
    • G01N27/83—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws by investigating stray magnetic fields
    • G01N27/84—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws by investigating stray magnetic fields by applying magnetic powder or magnetic ink

Definitions

  • the invention relates to a device for automatic testing of magnetic powder and including a device for automatic inspection of test samples to which magnetic powder has been applied.
  • Magnetic powder testing is a known method for examining whether fissures are present in test samples; in particular, fissures may occur in cast, hammered or rolled blanks and workpieces . Necessary is only that the sample is of ferromagnetic material. The sample is exposed to a magnetic field which is suitable for the test conditions, after which a fine iron powder is applied on its surface. If any fissure is present in the surface or close thereto, the powder is attracted by the magnetic field which forms lines of force at the edges of the fissure, which attract the powder. In order to discover the magnetic powder lines more easily, it is common to treat the powder with a substance which makes the powder fluorescent when illuminated with ultraviolet light.
  • a significant difficulty during automatic inspection in magnetic powder testing is to avoid incorrect indications due to varying surface properties of the sample. For example, smooth portions may occur as well as sections having a rough surface. In certain samples, smooth and machined surfaces, for example in the form of polishing marks after removal of cast material may occur. Such distinctions create a varying character of the reflected light. However, this should not lead to any detection of errors since discrimination of the samples due to varying surface properties should not occur. Such discrimination should only occur when fissures and fissure-like formations are present.
  • the object of the invention is to provide a device for automatic magnetic powder testing, including inspection of the workpiece, by means of which testing can be performed automatically, even for samples having a complicated shape.
  • the device scanning of the surfaces of the sample by means of a concentrated ray of light is utilized.
  • the light which is reflected from the surface of the sample is picked up in the same path as the path of the light ray inciding on the surface.
  • parallax errors can be avoided.
  • a light indication will be obtained.
  • the indication corresponds in a totally adequate manner to the state of the illuminated section, thus irrespective of whether any magnetic powder is applied to the surface or not.
  • An object of the invention is also to obtain as high safety as possible in the automatic inspection and to detect only fissures and similar formations as errors in the sample, whereas surface differences which are not supposed to give rise to any special treatment of the sample are not detected.
  • the device according to the invention is shown schematically as a central cross-section in the drawing.
  • the device comprises a support 1 for test samples 2.
  • the support is provided with means (not shown) for holding the samples which are intended to be treated in the device.
  • the support forms part of an arrangement with several stations and is moved together with the sample between these stations.
  • the shown station is the one in which the invention is applied, i.e. the inspection station.
  • This station comprises a light-proof cover 3 in which the support 1 can be inserted.
  • the inside of the cover 3 is provided with a black surface.
  • the cover is provided with a jacket 4 and a base 5.
  • a central hole 6 is formed in the base, around which hole a tubular support 7 is arranged.
  • a mirror 8 is arranged at an angle of 45°, which mirror faces a mirror 9 on the jacket 4 adjacent to the base 5.
  • the latter mirror is also arranged at an angle of 45°.
  • Another mirror 10 is mounted on the inside of the jacket at a distance from the base 5.
  • This mirror is also arranged at an angle of 45° and the mirrors are so arranged that a ray of light passing through the opening 6 towards the mirror 8 is directed towards the mirror 9, and from said mirror 9 and the mirror 10 towards the sample 2 which is centrally positioned inside the jacket 4.
  • the path which the ray of light follows is indicated by a chain line 12.
  • a light source 16 is arranged in the path 12 outside the mirror 14, which light source is arranged so as to transmit a concentrated ray of light in the direction of the path 12 and through the opening 15 of the mirror 14.
  • the mirrors 8, 9 and 10 Due to reflection in the mirrors 8, 9 and 10, this ray of light follows the path 12 and thus incides upon the sample 2.
  • the mirrors may be arranged at angles other than 45°, but must provide a light path from the light source to the sample.
  • the light source 16 should emit ultraviolet light.
  • an ultraviolet laser is used, since its monochromatic and coherent light cluster is very suitable for this purpose.
  • the mirror 14 Due to the fact that the mirror 14 is inclined in relation to the light path 12, it may direct the flow of light which is scattered outside che opening 15 at an angle in relation to the path 12.
  • a photoelectric unit 18 is arranged so as to face this flow of light which is deflected in this manner. The flow of light is indicated with a dotted line.
  • the light opening 15 is accurately adapted as regards it shape and size so as to provide a more concentrated cluster of light, of the kind which is obtained by direct reflection of the ray of light along the path 12 from surfaces on the sample which are so smooth that they provide direct reflection, which does not reach outside the edges of the light opening.
  • the light which is reflected from the collections of magnetic powder due to their contents of fluorescent material generates a more scattered light, which to some extent reaches outside the edges of the light opening 15 which is adapted as regards its size. In this manner, direct, reflected and concentrated light from the ray of light reflected by the mirror 14 and further to the photoelectric unit 18 can be avoided. Where magnetic powder collections occur and the light is reflected in a scattered manner, it will be reflected by the mirror 14 from its reflecting surface outside the edges of the light opening 15.
  • the cover 3 is arranged in a support portion 20 via its tubular bearing piece 7.
  • the support portion 20 is arranged with a drive device which is adapted to provide rotation of the cover 3.
  • the support is also arranged on a guide and can be provided with a reciprocating movement parallel to the longitudinal axis of the sample 2 by means of another drive device.
  • each point along this helix is represented by a predetermined angular position as regards the rotational movement of the cover and a predetermined coordinate as regards the longitudinal movement of the cover.
  • the light source 16 is connected to a current supply.
  • the photoelectric unit 18 is connected to a detection device which detects when light incides towards the unit 18.
  • the detection device is also adapted to detect the instantaneous angular position as regards the rotation of the cover and its instantaneous length coordinate, by means of sensors which are connected to the detection device.
  • the arrangement of which the above- described and shown apparatus forms a part consists of a number of stations between which the samples are moved.
  • the main stations for performing the operating steps of the magnetic powder testing are: a station for magnetization of the respective ferromagnetic samples, a station for applying ferromagnetic powder to which is added a component which is fluorescent in ultraviolet light, a station for rinsing the sample so as to discard magnetic powder which is not held due to the the magnetic force, after which a station with the above-mentioned inspection apparatus is arranged.
  • Service stations for example for initial cleaning and final washing of magnetic powder, may also be present.
  • a loading and removal station for the samples preferably provided with robots must be provided.
  • the sample is scanned by means of the light spot from the light source 16. This is accomplished by the rotational and longitudinal movement of the cover.
  • the photoelectric element 18 does not react. This is partly due to the fact that it has limited sensitivity for ultraviolet light and partly due to the fact that the light from the light spot on the clean surface of the sample is not scattered so that any substantial portion reflected light reaches the mirror 14 outside the opening 15.
  • a collection of magnetic powder occurs on the surface, its fluorescent component converts the ultraviolet light to visible light and also provides a light scattering.
  • the detection device will detect that a fault is present. As mentioned above, the detection device may at the same time be arranged to detect the position on the surface of the sample where the light spot is located. By combining these two detections, a value indicating the position on the sample where a fault occurs can be stored.
  • the detection device is adapted to control the removal station so that defective samples are sorted out. In cases of complete rejection, there is no reason to detect the position of the fault on the sample. However, in other cases there may be reason to post-examine the sample so as to determine if it can be adjusted so as to eliminate faults which occur, for example by removing the material where the fissure occurs or by suitable repairing. In this regard, it is important to obtain a protocol as to where the error is located. This the apparatus can thus be adapted for by means of said positional detection. Furthermore, the detection device can be arranged for selection of incoming detected data.
  • the detection device may be adapted to distinguish the shape of magnetic powder collections so that, for example, point-shaped collections do not lead to any error indication, whereas longish collections, which are typical for fissure formations, leads to an error indication.
  • the path of the ray of light which is directed towards the sample is the same as the path which the reflected light follows from the sample until this light is deflected towards the photoelectric unit.
  • This is accomplished by means of the mirror 14 which, due to its opening 15, is centered on said path but at the same time directed with the mirror's surface so as to deflect light outside the hole, with an angle in relation to the path, so as to convey it to the photoelectric unit.
  • Such a deflection can also be obtained by optical means other than an inclined mirror provided with a light opening.
  • a prism may for example be used in this application, as well as in other situations where the light is to be reflected.
  • the light opening may be a hole through the mirror or the prism, or a non-reflecting area, such as an area without any mirror coating.
  • the essential principle of the invention is not the choice of technical components but instead the fact that the light which is reflected from the sample follows the same path as the light which forms the light spot on the surface of the sample. Due to this arrangement, it can be assured that neither parallax errors between the illumination and the light detection nor shadow formations occur. In all positions where the ray of light may reach the surface of the sample so as to form a light spot, the thus illuminated area may also provide an indication to the light-sensitive detection unit.
  • the drawing shows the sample 2 with two flanges and a groove therebetween. If detection of the outgoing flow of light should occur at a certain angle in relation to the light flow of the illumination, the light spot between the flanges could be shadowed in certain positions of the light spot. In this manner, an error may remain unnoticed. It is particularly important to avoid this situation when using samples having a complicated shape, for example samples including holes or protruding portions.

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  • Chemical & Material Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Health & Medical Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Pathology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
  • Measuring Magnetic Variables (AREA)

Abstract

La présente invention concerne un testeur automatique de particules magnétiques destiné à tester des échantillons (2) sur lesquels on applique, après leur magnétisation, une poudre ferromagnétique. En cas de fissures, la poudre s'accumule autour des bords de ces fissures. Le testeur comporte une source lumineuse (16) dirigeant le trajet de lumière (12) vers l'échantillon de façon à produire un point lumineux sur sa surface, ce point lumineux se déplaçant en fonction d'une procédure de balayage. Un photodétecteur (18) détecte la lumière réfléchie lorsque le point lumineux arrive sur la surface de l'échantillon. La lumière réfléchie suit le même trajet que le rayon de lumière envoyé sur l'échantillon. En fonction de son ouverture, un photoréflecteur (14) à diaphragme variable (15) laisse passer la lumière concentrée réfléchie directement par la surface de l'échantillon, alors que la lumière diffuse imputable à l'incidence du rayon sur une accumulation de poudre magnétique est dispersée hors du diaphragme et atteint le photodétecteur après déflexion sur le photoréflecteur.
PCT/SE1996/000444 1995-04-05 1996-04-04 Dispositif de controle automatique de particules magnetiques WO1996031767A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU52941/96A AU5294196A (en) 1995-04-05 1996-04-04 Apparatus for automatic magnetic particle inspection
EP96909458A EP0819245A1 (fr) 1995-04-05 1996-04-04 Dispositif de controle automatique de particules magnetiques

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9501243-1 1995-04-05
SE9501243A SE9501243L (sv) 1995-04-05 1995-04-05 Apparat för automatisk magnetpulverprovning

Publications (1)

Publication Number Publication Date
WO1996031767A1 true WO1996031767A1 (fr) 1996-10-10

Family

ID=20397840

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1996/000444 WO1996031767A1 (fr) 1995-04-05 1996-04-04 Dispositif de controle automatique de particules magnetiques

Country Status (4)

Country Link
EP (1) EP0819245A1 (fr)
AU (1) AU5294196A (fr)
SE (1) SE9501243L (fr)
WO (1) WO1996031767A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8575923B1 (en) 2011-01-07 2013-11-05 OilPatch Technology Method and apparatus for special end area inspection
WO2024022835A1 (fr) * 2022-07-27 2024-02-01 Carl Zeiss Smt Gmbh Procédé, dispositif et procédé mis en œuvre par ordinateur pour inspecter un composant, en particulier un composant d'un système de lithographie, et système de lithographie

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0063760A1 (fr) * 1981-04-18 1982-11-03 Feldmühle Aktiengesellschaft Méthode et dispositif pour tester les surfaces intérieures de réservoirs ronds
GB2184321A (en) * 1985-12-17 1987-06-17 Medical Res Council Confocal scanning microscope
US5003831A (en) * 1989-03-10 1991-04-02 Isotopenforschung Dr. Sauerwein Gmbh Process for monitoring a device for automatically detecting and evaluating surface cracks
US5166813A (en) * 1988-05-31 1992-11-24 Nygene Corporation Optical evaluation using a hologram barrier filter
DE4311543A1 (de) * 1993-04-07 1994-10-13 Bayerische Motoren Werke Ag Vorrichtung zur Ermittlung der Konzentration einer Prüfflüssigkeit

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0063760A1 (fr) * 1981-04-18 1982-11-03 Feldmühle Aktiengesellschaft Méthode et dispositif pour tester les surfaces intérieures de réservoirs ronds
GB2184321A (en) * 1985-12-17 1987-06-17 Medical Res Council Confocal scanning microscope
US5166813A (en) * 1988-05-31 1992-11-24 Nygene Corporation Optical evaluation using a hologram barrier filter
US5003831A (en) * 1989-03-10 1991-04-02 Isotopenforschung Dr. Sauerwein Gmbh Process for monitoring a device for automatically detecting and evaluating surface cracks
DE4311543A1 (de) * 1993-04-07 1994-10-13 Bayerische Motoren Werke Ag Vorrichtung zur Ermittlung der Konzentration einer Prüfflüssigkeit

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8575923B1 (en) 2011-01-07 2013-11-05 OilPatch Technology Method and apparatus for special end area inspection
WO2024022835A1 (fr) * 2022-07-27 2024-02-01 Carl Zeiss Smt Gmbh Procédé, dispositif et procédé mis en œuvre par ordinateur pour inspecter un composant, en particulier un composant d'un système de lithographie, et système de lithographie

Also Published As

Publication number Publication date
EP0819245A1 (fr) 1998-01-21
SE9501243D0 (sv) 1995-04-05
AU5294196A (en) 1996-10-23
SE9501243L (sv) 1996-10-06

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