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
  • G01N21/90—Investigating the presence of flaws or contamination in a container or its contents
  • G01N21/9054—Inspection of sealing surface and container finish

Definitions

• the present invention relates to the field of manufacture of glassware, including control operations of the ring of an article.
• the glass articles are for example bottles or bottles manufactured industrially. In general, these items have defects such as glazes (cracks), broths, lack of material, excess material, etc. whose dimensions and positions can be random.
• the invention relates to a method for detecting a defect in a ring of a glass article, comprising the steps of:
• processing the shooting by analysis means configured to automatically detect an optical signature of the defect.
• Such a process is known to those skilled in the art. It is for example implemented in a number of machines or control devices. There are several types of control machines for detecting defects. These machines are generally specialized and only detect a type of defect.
• a ring is the upper zone of an article, most often provided with a bulge, and configured to cooperate with closure means.
• the defects present in or on this zone may be very small, which makes their detection difficult.
• control devices use detection systems based on video, optical and computer techniques, for example a CCD camera and a computer equipped with image processing and analysis software.
• particular lighting means are also used.
• the problem is indeed to place the defect in lighting conditions such that this defect appears more clearly or with a better contrast.
• the present invention aims to detect mainly glaze defects. Glazes are one of the glass defects that we do not know how to suppress in the manufacture of articles and whose consequence is the weakening of the resistance of the article to an internal or external pressure, and / or a traction, or still a shock, hence a risk of breakage.
• the positioning of the article with reference to the control means must be very precise in order to optimize the lighting conditions.
• the positioning between the article and the control means is a predominant criterion of performance.
• control means are integral with the frame of the convoy means, and include means for shooting.
• the articles are often simply placed on a conveyor provided with guide means which are either immobile, for example rails or slides, or movable, for example belts.
• an article generally has a bottom whose surface is greater than or equal to that of the ring, and the guide means act on the bottom or flanks of the article while the check is made for another area like the ring.
• the glass articles are, by their nature, subject to glass tolerances. These glass tolerances correspond to an axial displacement of the article such that the axis of symmetry of the ring is offset relative to the center of the bottom of the article, that is to say with respect to the longitudinal axis of the article. Article. This offset can reach the millimeter and strongly parasitizes the detection of defects.
• the detection of defects may be impossible because of the geometry of the ring on the one hand, and secondly the random angular position of the article. on the conveyor.
• the rings whose shape has no symmetry of revolution hereinafter referred to as screw rings, may be mentioned.
• the present invention aims to overcome these drawbacks by proposing a method essentially characterized in that it further comprises: a measuring step consisting in measuring the actual position of the ring relative to a reference position,
• the shooting step is performed by shooting means then positioned with reference to the article, and more specifically with reference to the position of the ring of the article.
• the shooting means are mounted movable relative to the article.
• the article is mounted movable relative to the shooting means, and in a third embodiment, the shooting means and the article are both mounted mobile, each of these three modes. embodiment allowing a relative movement between the shooting means and the article, that is to say its ring.
• the shooting means are movable in translation on a horizontal plane, parallel to the plane of the conveyor.
• the shooting means can be further movable on a vertical axis.
• the device according to the invention is advantageously provided with means for retracting the shooting means, in particular when they move along the vertical axis.
• the optical axis of the shooting means passes through the center of the ring, which ensures optimal detection.
• the step of processing the shooting includes a prior step of performing a shooting procedure and an angular registration relative to a reference frame.
• This embodiment is particularly advantageous for articles provided with a screw ring.
• the step of processing the shooting further comprises a masking step to eliminate the optical signature of a natural reflection in the detection of the optical signature of a defect.
• the method according to the invention can be implemented both for the articles of revolution and for the articles of form.
• the invention also relates to a device for detecting a defect in a glass article ring, comprising:
• - Analysis means configured to automatically detect an optical signature of the defect from the shooting.
• control means for transmitting a signal representative of the measured offset
• the device according to the invention is advantageously configured to implement the method according to the invention.
• the solution according to the invention makes it possible to dispense with the need to use specific samples of defects to parameterize the device implementing the method.
• the solution according to the invention can be advantageously applied to both flat rings and screw rings, by angular registration.
• the image-taking means comprise a light source and a plurality of output optical fibers, each of which is configured to respectively transmit the image of a given area (Z1, Z2, ... Zi) of the ring at a certain angle.
• the light source is connected to a plurality of input optical fibers, each of which is configured to illuminate the ring at a determined angle of incidence.
• the input fibers and the output fibers are all provided with a color filter and arranged so that the light emitted by an input fiber through a filter of a first color is essentially detected by an output fiber provided with a filter of an identical color of the first.
• the combination of colors used for the filters may be replaced by particular polarization angles.
• the shooting means comprise a light source and a peripheral assembly of at least one mirror, the peripheral assembly being configured to transmit the image of a given zone (ZR) of the corresponding ring. to all or part of the circumference of the ring via an optical return device.
• ZR given zone
• the means for processing the image of a given zone (ZR) of the ring comprise means configured to perform a scrolling of the image and an angular registration thereof relative to a reference reference.
• the analysis means configured to automatically detect an optical signature of the defect comprise masking means for eliminating the optical signature of a natural reflection in detecting the optical signature of a defect.
• the adjustment time of the devices implementing the method according to the invention is greatly reduced.
• the measurement rate is higher than that of the devices setting the article in rotation.
• the solution according to the invention can be implemented in particular for glassware used in the fields of perfumery, cosmetics, wines and spirits and food products.
• FIG. 1 represents a diagram in plan view of the device according to one embodiment of the invention.
• FIG. 2 shows a diagram of an embodiment of the shooting means according to the invention.
• the solution according to the invention makes it possible to detect the defects independently of the shape of the article or its ring.
• a glaze is a microcrack that generates a reflection phenomenon on the air / glass interface thus created.
• the The solution according to the invention consists in optimally positioning lighting means.
• the lighting means are positioned at different angles, that is to say different angles of incidence between an incident light ray and the glaze, in order to multiply the possible detection configurations.
• the detection means are positioned at different angles.
• ART glass articles for example bottles, are arranged vertically on conveying means CONV such as a conveyor.
• the conveyor is a moving belt of which at least a portion is linear and whose direction is illustrated by the double arrow in the X-X direction.
• the conveyor is a carousel.
• ART glassware has a B-ring at the top.
• the ring B of the article of revolution shown in Figure 1 is excessively eccentric.
• DETECT detection means make it possible in particular to control the triggering of the subsequent shooting for the presence check of the defects.
• the detection means are integral with the frame of the conveyor.
• the device comprises measuring means, possibly coupled to the detection means.
• the measuring means are configured to measure the actual position of the ring relative to a reference position, for example by an image from above the article, and a processing by computer means of the image obtained.
• Other means of measurement may be envisaged, for example telemetric means performing lateral measurements.
• the means for measuring the actual position preferably comprise a camera providing an image of the article, and image processing means configured to extract the geometrical coordinates of the article and / or its ring.
• the actual position measurement principle is based on image matching algorithm shape recognition methods.
• a camera takes an image of the article in a view from above.
• the ring image was previously registered as a reference.
• An area corresponding to the region of the image in which the ring may be located is defined as the search area.
• the reference model is superimposed on the image to compute a level of similarity
• the correlation algorithm is to search for a maximum of similarities. The entire search area is scanned. The maximum level of similarity is considered valid if it exceeds a threshold of acceptability.
• a servo device controlling at each article pass the position at which the means of Shooting must be located to provide the best measurement for control communicates with the means of measuring the actual position.
• repositioning means preferably act on the shooting means.
• these repositioning means may act on the article and / or on the conveyor.
• the repositioning means are therefore configured to act on at least one of the elements included in the set: shooting means, article, and conveyor.
• the reference position for the measurement of the possible offset of the ring is defined for example by a reference article or by an absolute position.
• the offset measuring means are integral with the conveyor frame.
• the actual position of the ring is transmitted to the shooting means.
• the signal representing the offset between the actual position and the reference position is transmitted for example in the form of instructions to repositioning means, configured to reposition the shooting means precisely with respect to the ring of the article to be checked.
• the measuring means make it possible to measure the difference between the actual position of the ring and a reference position and the value of this difference is transmitted to control means by a signal representative of the measured offset.
• This signal transmission can be wired or wireless.
• the device according to the invention comprises control means CTRL.
• the control means comprise VIEW shooting means.
• the shooting means are repositioned relative to the ring of the article. The repositioning makes it possible to bring the optical axis of the shooting means to pass through the center of the ring, which guarantees optimal illumination and analysis conditions.
• the repositioning of the shooting means is preferably performed by a servo along the Y-axis, perpendicular to the direction of the conveyor.
• a combination of the three repositionings is obviously possible.
• the shooting means are mounted on two lateral rails, integral with the frame of the device.
• the rails make it possible to slide the shooting means in a direction transverse to the direction of the conveyor.
• the displacement, in view of repositioning, is ensured for example by the rotation of a screw under the action of a motor.
• the repositioning stroke is determined by the previous measurement of the offset between the actual position of the ring and its reference position by the means for detecting and measuring the offset.
• the shooting means can also be rotatably mounted around the optical axis.
• control means are integral with the frame of the conveyor.
• the conveyor is essentially linear, and other types of controls can of course be performed on other stations along the conveyor.
• the conveyor comprises a turntable.
• This type of conveyor is advantageously used for articles of revolution.
• the article is loaded on an indexed rotary plate (carousel) comprising several cells and stations.
• the entire plate is driven in a rotational movement to place each cell in a succession of positions corresponding to various operations, one of which corresponds to the control according to the invention.
• each carousel station can be equipped with accessories to perform a given type of control.
• controls uncoupling diameter, sealing, ring surface, ring glaze, body thickness.
• the shooting means take a shot of a sample of the ring.
• the sample can be partial or total.
• the shooting means comprise a light emission transmission system.
• the emission of light is performed by a light source.
• the light source may be single or multiple, for example a set of light-emitting diodes (LEDs).
• the light emission is orientable, for example by a set of input optical fibers connected to the source and each of which is configured to illuminate the ring at a determined angle of incidence. .
• the light receiving means also comprise a set of photoreceptors, for example about twenty, judiciously arranged.
• the photoreceptors are image transfer output optical fibers each making it possible to transfer the image of a given area Z1, Z2,... Zi, fraction of the ring to the article.
• the detection thereof is favored according to the angle of the receivers.
• the relative orientation of the receivers and emitters therefore makes it possible to promote the detection of a given type of glaze.
• the glaze when the article is rotated (about its axis of revolution) for the control operation, the glaze is at a time at such an angle with respect to one of the light sources that a large reflection is generated and a peak of light is easily detected by one of the photoreceptors.
• This embodiment is particularly suitable for articles of revolution.
• the article is not rotated for the control operation.
• a fixed assembly of transmitters and receivers, mounted on a support collects a plurality of partial images which are then processed by computer means to eliminate spurious reflections due to the faces of the ring, for the rings of revolution, and screw threads, for screw rings.
• the detectors are advantageously arranged in places that maintain a high signal-to-noise ratio, which facilitates the automatic detection process of an optical signature of a defect.
• the input fibers and the output fibers are further all provided with a color filter and arranged so that the light emitted by an input fiber through a filter of a first color is essentially detected by an output fiber provided with a filter of an identical color of the first.
• the imaging means comprise an optical head (not shown) provided with diffuse lighting, preferably arranged on the optical axis and configured to illuminate a glass article by above, and optical imaging means using an optical return of the image obtained from the article illuminated by a peripheral mirror MIR having a symmetry of revolution and forming the image on a CAM camera.
• the light emission / reception assembly has a symmetry of revolution.
• the unitary peripheral mirror for obtaining a peripheral image of the ring can be replaced by a circular assembly of faceted mirrors contiguous to each other.
• the mirror or the set of mirrors are circular and the center of symmetry of these reflection means coincides with the center of symmetry of the ring of the article.
• the image of the ring is sent back to a camera by means of an optical return device, such as a reflecting cone arranged along the optical axis, as represented in FIG.
• the arrows represent the optical path of the source (not shown) to the camera.
• Optical focusing means such as a lens, may be mounted upstream of the camera.
• the illumination and detection means are lateral.
• the device according to the invention comprises a plurality of imaging means and / or a plurality of processing means configured to automatically detect an optical signature of a defect. Several types of faults can thus be detected by a single device.
• the means of shooting that is to say the lighting means and the reflection detection means are preferably mounted movable in translation and are integral with each other.
• a measuring device such as a video camera or an optical sensor, retrieves the images of the article to be checked and communicates them to analysis means.
• This measuring device is preferably disposed close to and can be fixedly mounted.
• the analysis means are configured to automatically detect an optical signature of the defect.
• the disadvantage of optical fibers is that the images produced by all the receivers only make it possible to construct a partial image of the ring of the controlled article. The interpretation of the results is then more difficult.
• the analysis means are further configured to process images from the shooting means when they communicate a complete sample of the ring by a set of mirrors. In this case, the analysis means perform a roll of the image so as to make a flat image of all or part of the ring. Any angular offset due to the random angular position of the article on the conveyor is compensated by an angular registration step. This step is carried out thanks to a reference mark preferably located on the article.
• the analysis means comprise masking means which aim to eliminate the optical signature of a natural reflection and allow the automatic detection of the optical signature of a defect.
• the masking operation does not associate a natural reflection with a defect, whose optical signature is also a reflection.
• the variations of the position of the reflection (natural or defect) in the image of the shooting is in direct relation with the position, in particular the angular position, of the article under the means of shooting.
• the position in particular the angular position, of the article under the means of shooting.
• reflections will appear at a different position.
• the operator is forced to widen the mask, which reduces the possibilities of detection.
• This problem is solved by the second embodiment including a step of unrolling the image.
• This embodiment makes it possible to distinguish between natural reflection and defect irrespective of the angular position of the screw ring, thanks to the angular registration operation with respect to a reference mark.
• the reference mark may for example be the beginning of the thread or a mark on the article (especially on the ring) as the seam.
• the detection of an optical signature of the defect is carried out by means of a masking operation, aimed at detecting the absence of a light signal or the presence of a light signal on a given area of the image obtained. by the shooting means, so as to eliminate the optical signature of a natural reflection in the search for the optical signature of a defect.
• a test is carried out by non-defective articles brought constantly in a given angular position, then by defective articles brought into the same angular position,
• a second step the same test is performed with transverse positions of the articles on the random conveyor, within a limit of plus or minus the diameter of the ring.
• the first time is performed for a maximum of given angular positions.
• the steps of the method according to the invention are sequential: detection of the presence of an article, measurement of the offset of the ring, repositioning of the means of shooting, then shooting and automatic analysis of an optical signature .
• the delay between each phase may be of the order of 250ms.
• the steps can be interleaved, that is to say for example that the detection of a new article can be performed before the optical signature analysis of the previous article on the conveyor is completed.
• any type of article can be treated.
• Articles of revolution can be controlled in a device such as a carousel, and shaped articles on a linear conveyor.
• a device such as a carousel
• flat ring means for shooting comprising a plurality of optical fibers may be used.
• means for shooting comprising a peripheral mirror
• analysis means configured to carry out an unwinding and an angular registration of the image obtained.

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• 2006
  • 2006-05-10 FR FR0604313A patent/FR2901022B1/fr active Active
• 2007
  • 2007-02-19 US US12/299,649 patent/US20090066944A1/en not_active Abandoned
  • 2007-02-19 WO PCT/FR2007/000301 patent/WO2007128888A1/fr active Application Filing
  • 2007-02-19 EP EP07731011A patent/EP2016397A1/de not_active Ceased

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