WO2000022574A1 - Verfahren zur kontrolle einer flächigen oder räumlichen verteilung - Google Patents
Verfahren zur kontrolle einer flächigen oder räumlichen verteilung Download PDFInfo
- Publication number
- WO2000022574A1 WO2000022574A1 PCT/EP1999/007244 EP9907244W WO0022574A1 WO 2000022574 A1 WO2000022574 A1 WO 2000022574A1 EP 9907244 W EP9907244 W EP 9907244W WO 0022574 A1 WO0022574 A1 WO 0022574A1
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- WO
- WIPO (PCT)
- Prior art keywords
- image
- picture elements
- brightness values
- spray jet
- particles
- Prior art date
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Classifications
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/40—Analysis of texture
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B12/00—Arrangements for controlling delivery; Arrangements for controlling the spray area
- B05B12/08—Arrangements for controlling delivery; Arrangements for controlling the spray area responsive to condition of liquid or other fluent material to be discharged, of ambient medium or of target ; responsive to condition of spray devices or of supply means, e.g. pipes, pumps or their drive means
- B05B12/082—Arrangements for controlling delivery; Arrangements for controlling the spray area responsive to condition of liquid or other fluent material to be discharged, of ambient medium or of target ; responsive to condition of spray devices or of supply means, e.g. pipes, pumps or their drive means responsive to a condition of the discharged jet or spray, e.g. to jet shape, spray pattern or droplet size
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B12/00—Arrangements for controlling delivery; Arrangements for controlling the spray area
- B05B12/08—Arrangements for controlling delivery; Arrangements for controlling the spray area responsive to condition of liquid or other fluent material to be discharged, of ambient medium or of target ; responsive to condition of spray devices or of supply means, e.g. pipes, pumps or their drive means
- B05B12/084—Arrangements for controlling delivery; Arrangements for controlling the spray area responsive to condition of liquid or other fluent material to be discharged, of ambient medium or of target ; responsive to condition of spray devices or of supply means, e.g. pipes, pumps or their drive means responsive to condition of liquid or other fluent material already sprayed on the target, e.g. coating thickness, weight or pattern
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- 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
- G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/40—Analysis of texture
- G06T7/41—Analysis of texture based on statistical description of texture
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2207/00—Indexing scheme for image analysis or image enhancement
- G06T2207/20—Special algorithmic details
- G06T2207/20021—Dividing image into blocks, subimages or windows
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2207/00—Indexing scheme for image analysis or image enhancement
- G06T2207/30—Subject of image; Context of image processing
- G06T2207/30108—Industrial image inspection
Definitions
- the invention describes a method with which the distribution of structures on a surface or of particles in space can be controlled automatically.
- warning messages can be automatically issued locally or at a remote location and / or corrective measures can be initiated.
- the method is suitable, for example, for automatically checking the success of cleaning, chemical conversion and / or coating of surfaces such as metal or plastic surfaces without the need for human intervention.
- One area of application is, for example, the control of surface conversions or coatings in the steel industry and in vehicle construction.
- the method is also suitable, for example, for controlling the spatial distribution of particles in a spray jet. On the one hand, the opening angle of the spray jet and, on the other hand, the homogeneity of the particle distribution in the spray jet can be controlled automatically.
- US-A-4,878,114 describes a processor-based optical system for assessing the roughness of a planar surface of a product.
- This system includes one adjustable light source for illuminating the surface, a video camera and a device for storing the output of the video signal in digitized form and a processor for analyzing these digitized signals in such a way that a parameter is determined which reflects the roughness of the surface.
- EP-B-255 177 teaches a method for automatically recognizing a contrasting object in a video image stored in digital form. For this purpose, threshold values are defined above the background values above which an image element is considered to belong to a contrasting object. The method is therefore set up to recognize a pattern in a video image. It is not suitable for analyzing the occurrence and the spatial distribution of disturbances in an otherwise largely uniform video image if these disturbances do not describe a coherent object.
- EP-B-428 751 provides a measurement method to assess the quality of paper. Fluctuations in the light transmission of the paper are assessed. It is a method for measuring textures, comprising taking a picture of transmitted light from a light source on a paper area by a camera to display the picture of the transmitted light on a display unit of an image processing computing element, dividing the picture of the transmitted light the display unit into a predetermined size and number of windows, characterized by calculating an average value of the intensity and a primary variance of the intensity of each window from the intensity of each of the pixels in each of the windows, calculating an average value of the primary variance for all Windows and a secondary variance of this first variance for all windows and use of the secondary variance for all windows as a texture factor.
- This method therefore provides a single indicator that describes the uniformity of the transmitted light and thus the homogeneity of the paper structure. This procedure does not recognize individual defects and their position on the paper surface.
- EP-B-159 880 relates to a device for assessing the density and uniformity of a pattern such as letters printed on an article.
- the apparatus is characterized by means for computing the density distribution of a plurality of image data in each of a plurality of segments of the pattern by sampling the density of each pixel of the image data; means for checking the density distribution within each segment and for those segments in which the density distribution satisfies a predetermined function, for normalizing the density distribution in each such segment by dividing each value of the density distribution by a value representing the total density in said segment ; and means for quantifying the density and uniformity of the patterns based on the density distributions normalized by the determining and normalizing means, in which the uniformity is defined as the degree of change in a normalized density within the patterns.
- This method is not designed to identify the occurrence and location of local disturbances in the pattern.
- Another group of technical processes such as phosphating, aims to chemically transform a metal surface in order to protect this surface from corrosion, for example. Disruptions to these processes are noticeable as defects in the otherwise uniform coating of the surface. These defects are shown on a picture of the surface by a deviation of their brightness from the average brightness of the surface. The same applies to the coating of surfaces with corrosion-protective coatings such as paints. Faults in the uniform layer of paint, such as bubbles or craters, are also noticeable as spots whose brightness value differs greatly from the average brightness of the surface.
- the determination of the opening angle of the spray jet at the nozzle and the uniform spatial distribution of the particles in the spray jet are important.
- the blockage of individual nozzles of a nozzle head is shown by the fact that the space in front of the individual blocked nozzle is less densely filled with particles than in front of the correctly working nozzles. If spraying is used to obtain product by spray drying or spray solidification, clogged nozzles lead to a reduced space-time yield. However, if the spray is used to apply the particles as evenly as possible on a surface, clogged nozzles lead to an uneven surface coating.
- the spray jet has a certain opening angle.
- the uniformity of a surface during surface treatment processes or the uniform distribution of the particles in a spray jet or its opening angle are generally assessed directly by visual assessment of the surface or the spray jet or by photographic recordings thereof. On the one hand, this requires human intervention. On the other hand, the visual assessment can only be carried out at defined points in time, if the workforce is not to be tied up by the fact that personnel are used exclusively to continuously visually monitor the production result. If the inspection takes place, as is usually the case, only at certain times, there is a risk that defective goods were produced between two inspection times.
- the object of the invention is to continuously monitor automated working or manufacturing processes, in which the quality of the result is shown either as a uniform-looking surface or as a uniform filling of particles, and to output warning messages in the event of faults and / or the causes of the Analyze faults and eliminate them if possible.
- the invention accordingly relates to a method for controlling the distribution of structures on a surface or of particles in space, characterized in that a) at least one two-dimensional image of the distribution is generated optically or electronically, broken down into pixels and the brightness value of each pixel in stores digitized form on a data carrier, b) divides the image or an image section thereof into a preselected number of picture elements arranged in rows, each picture element comprising at least four picture elements c) determines the average brightness value of each picture element by averaging the brightness values of the individual picture elements of this picture element , d) along a first predetermined row of picture elements, the difference between the average brightness values of adjacent picture elements is determined and recorded in a machine-readable manner on a data carrier and / or output as a diagram that a local correlation of the difference values to the position of the associated picture elements on the picture is obtained, and if desired e) repeating step d) with a preselected number of further rows of picture elements which run essentially parallel to the first predetermined row.
- sub-step a) “at least one two-dimensional image” means that one image or more images of the distribution are taken. As a rule, one image is sufficient for the assessment of an essentially flat surface. For the assessment of a spatial distribution or However, if the surface is very curved, it may be advantageous to take several images, the image planes of which form predetermined angles with one another. As a result, the surface or the spatial distribution can be assessed from different viewing directions.
- a video camera is preferably used to generate the image
- the image section can be adjusted by the focal length of the video camera and / or by the distance of the camera from the object to be assessed If very small sections of an object are to be assessed, as may be necessary, for example, to check the conversion treatment of metal surfaces, the video camera can also be used be provided with a microscope device.
- this method presupposes that the surface to be imaged or the spatial area to be recorded is sufficiently well illuminated.
- a device as described in US Pat. No. 4,878,114 can be used for the recording and storage of the image information in digitized form.
- the image or a preselected image section thereof is broken down into a likewise preselected number of image elements arranged in rows.
- the maximum number of picture elements depends on the resolution of the camera used.
- the pixel (pixel) is the smallest possible image section due to the resolution, to which a brightness value (gray value) can be assigned.
- the picture can therefore be broken down into a maximum of as many picture elements as picture elements (pixels) are assigned to it.
- picture elements are advantageously selected which comprise several picture elements.
- the average brightness value (gray value) is determined for each picture element by adding the brightness values of the individual picture elements and dividing the sum of the brightness values by the number of picture elements.
- a picture element is selected at least so large that it comprises at least 4 picture elements, which are preferably arranged in pairs next to one another. Depending on the question, however, a picture element can also comprise considerably more picture elements.
- each row of picture elements contains at least 2 of these picture elements.
- the number of picture elements per row is advantageously chosen to be substantially larger, for example in the range from about 10 to about 200 picture elements, in particular about 15 to about 100 picture elements per row.
- more reliable statements can be obtained if the image or the image section is broken down into several rows, since this allows a larger section from the surface or from the spatial area to be included in the analysis.
- the image or the image section is broken down into as many rows of picture elements as each row has picture elements.
- the image or the image section is broken down into about 10 to about 200, in particular in about 15 to about 100 rows.
- the area or space that you take as a picture correlates with the number and size of the picture elements. As a rule, an area or a spatial section that has a side length between approximately 1 mm and approximately 5 m is advantageously depicted.
- the respective image section can be adjusted by a corresponding distance of the camera from the object, by the focal length of the lens and, if necessary, by using a microscope device. If the method is used, for example, to assess the result of a chemical surface treatment, it can make sense to record and display a surface section in the range of 10 x 10 cm. For the assessment of a coating on a surface or the uniformity of a spray jet, image sections in the range of 30 x 30 cm can be particularly favorable.
- the average brightness value (gray value) of each picture element is determined by adding the brightness values of the individual picture elements of the picture element and dividing the sum obtained by the number of picture elements. This will reduce the background noise. If this is not sufficient, arithmetic filter processes such as e.g. B. Gauss filter or Fourier filter can be used. Gaussian filtering is also carried out, for example, in EP-B-255 177 cited at the beginning. In the context of the method according to the invention, however, such filter processes are only required in exceptional cases.
- arithmetic filter processes such as e.g. B. Gauss filter or Fourier filter can be used. Gaussian filtering is also carried out, for example, in EP-B-255 177 cited at the beginning. In the context of the method according to the invention, however, such filter processes are only required in exceptional cases.
- sub-step d the actual criterion for assessing the uniformity or for recognizing irregularities is generated. Furthermore, the opening angle of a spray jet can be obtained from the results of sub-step d) determine how to explain further below. It is essential to the invention to record or output the difference values between the brightness values of adjacent picture elements in such a way that it can be recognized which location on the surface or in the image shown
- Specks (bright crater-shaped defects) in a crystalline phosphating layer, the occurrence, the number and the spatial distribution of these disturbances can be recognized.
- Line or area-like disturbances such as, for example, uncoated or otherwise coated areas on the surface can be identified by the fact that in each row of picture elements the edge of the disturbed surface is adjacent as a particularly strong difference in the brightness values
- Picture elements usually 2 particularly strong difference values of the brightness values of neighboring picture elements are determined, the beginning and the respectively
- the difference between the brightness values of neighboring picture elements must still be accepted as noise and the threshold value above which the difference is characterized as a disturbance.
- the basic brightness of the image which depends, for example, on the illuminance, plays no role in the method according to the invention, since the absolute brightness disappears when determining the differences in the brightness values of adjacent picture elements.
- one or more light sources can be used for this purpose, the light cone of which runs as parallel as possible to the direction of acquisition. This minimizes shadowing.
- 2 to 4 light sources are preferably used, which are arranged around the camera used for recording.
- correction values or the area on which they lie can be determined, for example, by the method of the minimal square deviation of the individual observed brightness values from a compensation plane, which then represents the area of the correction values. This can have the effect computationally compensated for, that with an oblique illumination part of the picture appears systematically darker than another.
- sub-step e) the sub-step d) is repeated with a preselected number of further rows of picture elements characterized as above, which are essentially parallel to the first given row.
- a parallel course of the rows is preferable if the image section to be analyzed is rectangular and in particular square. As a rule, this will be preferred.
- the viewing direction of the camera is not at least largely perpendicular to the surface to be recorded or to the axis of the spray jet to be recorded, the recorded image contains a perspective distortion.
- each picture element corresponds to the same area of the recorded object or spatial section.
- the rows of picture elements do not necessarily run parallel, but can form a (small) angle with one another, which reflects the perspective distortion of the section of the surface or the spray jet depicted.
- the method according to the invention can be used, for example, to control the distribution of structures on a metal or plastic surface.
- a section from the surface that is as flat as possible which in turn is taken from a viewing direction that is as vertical as possible.
- the evaluation of a curved surface or an oblique viewing direction can be adapted by already considering the perspective view when selecting the individual image elements.
- the size of the individual picture elements is preferably chosen such that each picture element represents an essentially equally large area of the recorded object.
- the method can be used to control a metal or plastic surface, in which the success of cleaning and / or hydrophilization is checked.
- Successful cleaning and / or hydrophilization can be recognized by the fact that the surface is covered with a uniform liquid film after leaving the treatment zone.
- inadequately cleaned and / or hydrophilized areas are noticeable in that the water film breaks up and converges to form drops or pools of water.
- these can in turn be recognized with appropriate lighting by their brightness values which differ from the uniform background.
- the area to be inspected can also be a metal or plastic surface that has been subjected to a chemical treatment (for example cleaning or "conversion treatment” that changes the chemical nature of the surface) or a coating.
- a chemical treatment for example cleaning or "conversion treatment” that changes the chemical nature of the surface
- it can be act a metal surface that has been subjected to a chemical treatment in the form of chromating, a treatment with an acidic solution of simple and / or complex fluorides, a treatment with a solution of transition metal compounds or a layer-forming or non-layer-forming phosphating.
- Such treatment steps are for a corrosion protection treatment - if necessary
- metal surfaces such as surfaces of iron, steel, galvanized or alloy galvanized steel or of aluminum and its alloys are well known metal-producing industry such as the steel industry or in the metal-processing industry such as in vehicle construction or in the household appliance industry routinely used to improve corrosion protection.
- a special field of application for the method according to the invention is the assessment of the quality of a layer-forming phosphating in vehicle construction.
- quality defects are noticeable due to disturbances in the uniformity of the phosphate layer.
- these disturbances can be essentially point-like, for example the so-called “phosphating specks”.
- the disturbances can also be extensive and consist, for example, of unphosphated or less densely phosphated metal sites has a size of 10 x 10 cm. This picture is divided into so many picture elements that the approximately 0.5 up to about 2 mm extended phosphating specks are still recognizable as a single fault.
- the method can be used to control a metal or plastic surface that has been subjected to a coating with crosslinkable organic substances.
- a typical example of this is painting, which can be carried out, for example, in the form of electro-dip painting, but also by immersion in a paint bath or by spraying with the paint.
- Such coatings are usually cured after application by heating, by irradiation with infrared radiation or also photochemically, in which case correspondingly reactive molecules combine with one another and thereby crosslink.
- Lacquer layers of this type can have different faults. This can be, for example, rather punctiform faults such as bubbles or craters in the lacquer layer or also embedded dust or dirt particles which are noticeable as a bulge in the lacquer layer.
- the method according to the invention takes an image of the surface to be checked after the work step to be checked (cleaning, chemical treatment, coating) and to analyze this image.
- the brightness distribution of the image can be shaped primarily by the structure of the metal surface itself.
- this can be the case with hot-dip galvanized steel, where the brightness distribution of the metal surface is strongly influenced by the crystalline structure of the zinc layer.
- the procedure here is to produce a first image of at least approximately the same location on the metal or plastic surface before and a second image after the chemical treatment or coating according to sub-step a), before or after carrying out sub-steps b) and c ) for the second image, the two images are at least approximated mathematically by looking for characteristic locations on the metal or plastic surface that can be seen on both images, at least approximating these characteristic locations on both images and then the brightness values subtracts the pixels or the average brightness values of the picture elements in the first picture from the brightness values of the corresponding picture elements or picture elements in the second picture before performing the sub-steps d) and, if desired, e) with the second picture.
- the two images are covered at least to such an extent that corresponding image elements at least largely overlap on both images.
- deviations of the order of millimeter fractions up to several millimeters are tolerable.
- characteristic points that can be used to computationally overlay the two images For example, corners or edges created by bending or folding are suitable, or also small-area joints such as welding spots.
- the method can be used, for example, for quality control of cleaning processes, chemical conversion processes and coating processes. It can be determined, for example, which area of the difference values of the brightnesses of neighboring picture elements is regarded as the normal area. A range of larger difference values can be defined as a control range. It is tolerable here if the differences in the brightness values of neighboring picture elements per picture may lie up to n times in this control area, where n means a number to be specified> 1. If more than n difference values are found that are in the control area, or if at least one difference value exceeds the control area, one of the following actions can be triggered automatically:
- both measures i) and ii) or i) and iii) can be triggered simultaneously.
- the number of difference values between the brightness values of adjacent picture elements which are in the normal range, which are in the control area and which are outside the control area are continuously recorded on a data carrier.
- the recording is preferably carried out in such a way that the difference values remain assignable to the treated object for which they were found.
- a machine-readable bar code can be used for this.
- the treated object can be, for example, a steel coil or a section thereof or, in the case of vehicle construction, a specific vehicle. This makes it possible to automatically keep and archive records that are required for quality control and quality assurance.
- this remote location can be located at the manufacturer of the chemicals that are used for the surface treatment steps to be checked. In this way, the manufacturer of the treatment chemicals is continuously informed as to whether the corresponding treatment steps for the user of these chemicals take place in accordance with the standards.
- the computer system which carries out the method according to the invention can, according to alternative ii), check at least one cause the treatment or coating agent with which the metal or plastic surface came into contact before sub-step a). This can also be initiated automatically if the control system for the method according to the invention determines that the number of difference values which lie in the control area increases by a predetermined amount.
- measure ii) can be provided to check predetermined parameters of the phosphating bath or treatment baths connected upstream thereof, such as cleaning or activating baths.
- an automatic analysis of parameters to be specified for the phosphating bath, the activation bath or the cleaning baths can be started.
- one or more of the following parameters can be automatically analyzed: alkalinity, surfactant content and / or fat level in the cleaning bath.
- automatically running analysis methods can be initiated, as described for example in German patent applications 198 02 725, 198 14 500 and 198 20 800. In connection with these bath control measures, it can in turn be provided that corrective measures are automatically initiated if the bath parameters deviate from the target values.
- control method according to the invention By combining the control method according to the invention with an analysis of the upstream treatment baths, which in the case of deviations from the control system is found, which in turn can automatically result in corrective measures for the composition of the treatment baths, it is possible to ensure the success of a surface treatment automatically and continuously without it this requires human intervention. It is advisable to save the results of the control method according to the invention and the analysis and correction measures initiated in the event of a deviation for later evaluation.
- the control system automatically switches off the entire system if the number of difference values between the brightnesses of neighboring picture elements in and / or outside the control area exceeds a predetermined number. It is preferable that the system issues a corresponding message locally and / or at a remote location, so that the operator of the system can intervene manually as quickly as possible and the present fault can be remedied.
- the method according to the invention can furthermore be used to control the distribution of particles in a particle beam by checking at least one image of a particle beam generated by spraying through one or more nozzles. It is advisable to take the image essentially perpendicular to the spray axis in order to avoid major perspective distortions. As explained above, slight perspective distortions can be compensated for by dividing the image into picture elements in such a way that each picture element comprises an equally large section of the spray jet and / or the space surrounding it.
- a fan-like spray jet in particular, it may be sufficient to record a single image of the spray jet that is recorded as perpendicularly as possible to the fan plane.
- a conical spray jet in the case of a conical spray jet, on the other hand, it may be preferable to record several images of the spray jet, which are recorded from different viewing directions. This means that in this case the sub-steps a) to e) of the method according to the invention are repeated one or more times with images whose image planes (and thus their plane normals) form predetermined angles with one another.
- an essentially conical spray jet it may be sufficient to carry out the method according to the invention using two images, the image planes of which are essentially perpendicular to one another.
- This can be, for example, a particle beam, the particles of which consist of droplets of a solution or a suspension which are dried to solid particles in the particle beam. Or it's a droplet Melt that solidifies into solid particles in the particle beam.
- the first case describes a typical spray drying process in which a solution or a suspension of a valuable substance is sprayed into a vacuum and / or into a zone of elevated temperature, the solvent or the suspending agent evaporating. As a result, the valuable materials are obtained in powder form.
- Such processes are used in different industries. Examples include use in the food industry, where food or luxury powder is produced in this way. Examples are powdered milk and coffee. Spray drying processes of this type are also customary, for example, in the detergent industry in order to obtain detergent active ingredients in powder form.
- the method according to the invention allows checking whether the spray device is operating in accordance with the standard, whether the spatial distribution of the spray jet is outside the normal range due to signs of wear on the nozzles or whether inhomogeneities in the spray jet occur due to clogging of individual nozzles of a nozzle collection. It can therefore be checked whether the spraying process runs optimally or whether a reduced throughput is to be feared due to malfunctions.
- the particles of the spray jet can be droplets of a solution, suspension or melt, which are sprayed onto a surface in order to produce a coating on this surface.
- Liquid paints or paint dispersions are an example of this.
- it can also be solid particles with which a surface is coated.
- An example of this is powder coating. In both cases, irregularities in the spray jet lead to an uneven coating of the surface and thus to quality defects.
- Analogous to the measures described above in the control of treatment processes of surfaces can also in the control of Particle distribution can be provided in a spray jet so that a warning message is automatically issued locally or at a remote location if the difference in the brightness values of adjacent picture elements within the particle jet exceeds a predetermined amount. How it can be determined whether picture elements are inside or outside the spray jet is explained below using the example of checking the opening angle of the spray jet. This enables a continuous and automatic control of spraying processes without human intervention.
- the method can be used to control the opening angle of a particle beam, which is obtained by spraying through one or more nozzles.
- This can be important for spray drying or spray solidification processes, for example.
- the spray jet must not fan out too little, since otherwise the drying or solidification takes place only unreliably and there is a risk of particles clumping together.
- the spray jet must not fan out too far, since it must be prevented that sticky or viscous droplets get onto the wall of the spray tower and stick to it.
- the opening angle of the spray jet is in principle predetermined by the arrangement of the nozzles, but can change if the nozzles wear out or become encrusted. Furthermore, the opening angle of the spray jet depends on the correctly set spray pressure.
- a spray jet is used to coat surfaces, such as coating with paint or with underbody protection in motor vehicles, care must also be taken to ensure that the spray jet angle is correct.
- the surface to be coated is only sufficiently uniform and coated with the correct layer thickness if the spray jet opening angle is set correctly.
- the section of the spray jet to be recorded for the determination of the spray jet angle depends primarily on the width of the spray jet. For the production of mass products such as detergents by spray drying, the spray jets have a considerable extent in the range of meters, so that a corresponding section must be included for the determination of the opening angle. An image section with a side length of up to 5 m can be useful for this.
- an image section in the range from a few centimeters to a side length of about one meter is usually sufficient.
- an image section in the range of approximately 10 to approximately 50 cm side length, in particular in the range of approximately 30 ⁇ 30 cm, is suitable, for example.
- the procedure is preferably such that the image is broken down into lines which are perpendicular to the axis of the spray jet.
- a sufficient number of picture elements is selected in each line (in the range from approximately 10 to approximately 200, preferably approximately 15 to approximately 100 picture elements per line) and the differences between the brightness values of adjacent picture elements are formed, starting from an edge of the picture.
- the differences in the brightness values of picture elements that only represent the background are relatively small with suitable lighting.
- the difference in the brightness values of adjacent picture elements one of which mostly contains the image of the background and the other mostly contains the image of the spray jet, will have an unusually high value.
- the differences in the brightness values of neighboring picture elements that only contain the spray jet will again be relatively small (as long as the spray jet is not too inhomogeneous). In the course of forming the difference, you feel your way towards the spray jet from the background and move over the spray jet until you get back into the Area of the background. The last strong difference value between the brightnesses of neighboring picture elements then corresponds with a very high probability to the edge of the spray jet.
- a first high difference value when detecting the one edge of the spray jet, slightly fluctuating difference values in the area of the spray jet and again a particularly high difference value corresponding to the other edge of the spray jet.
- this method presupposes that the image section is chosen so large that in addition to the image of the spray jet, the image of the background is also recorded on both sides. This can be checked automatically by the fact that the image must lead to the pattern of difference values described above.
- the preferred procedure here is to begin by determining the differences in the brightness values of adjacent picture elements in the picture line that is closest to the spray head. Since one knows its extent, it can best be ensured here that the image line contains an image of the spray jet in its central region and an image of the background in both edge regions. One continues the evaluation line by line away from the nozzle head and checks whether the positions of extreme differences between the brightness values of neighboring picture elements shift outwards in each subsequent line. This will be the case as long as an image line comprises background at both ends and spray in its central region. This method is terminated when the extreme differences between the brightness values of adjacent picture elements reach the edge area of a picture line, since there is now a danger that the picture line now only contains a spray jet but no background.
- the opening angle of the spray jet can be determined by laying a straight line through at least 2 significant points, preferably a compensating straight line through several points, in the individual image lines using the points of first large difference values between the brightnesses of adjacent picture elements.
- a second straight line or equalizing line is placed on the individual lines through the points of the last high difference values of the brightnesses of neighboring picture elements.
- the course of the two straight lines in the picture can be represented as a vector.
- the opening angle of the spray jet can be calculated from this by using vector algebra.
- the evaluation unit for the method according to the invention can be specified in which area of the image the first and last high differences between the brightness values of adjacent image elements on selected image lines must lie. If the extreme values of the differences in the brightness values found are located further inside, the opening angle of the spray jet has decreased, if they are further outside, the opening angle has increased.
- the spray jet angle has changed outside of a tolerance range, ie one or more of the following actions can be initiated: i) issuing a warning message; ii) Change of the spray pressure in the direction that the opening angle of the spray jet again in the predetermined angular range brings; iii) changing the viscosity of the composition from which the spray jet is generated in the direction which brings the opening angle of the spray jet back into the predetermined angular range; iv) change in the electrical charge of the particles of the spray jet or of electrical fields in the vicinity of the nozzles in the direction which the
- a warning message can be issued locally or at a remote location. It can be provided that a warning message is issued if the opening angle of the spray jet changes slightly, but no further action is started yet. Only when a predefined threshold of the deviation of the spray jet angle is reached can one of the actions ii) to iv) be triggered automatically. Of course, it can also be provided that the spraying process is stopped completely if the spray jet angle falls below or exceeds a limit value to be specified.
- the control system can be predefined whether the opening angle of the spray jet should take place by changing the spray pressure, by changing the viscosity of the composition to be sprayed (for example by changing the temperature of the composition in the spray head) or by changing electrical charge.
- the control unit can be specified which change in the spray conditions should lead to an increase or decrease in the spray jet angle.
- the control system can also be designed in such a way that it learns itself which measure returns the opening angle of the spray jet to the desired range with the greatest reliability. For this, the control system can determine the possible spray parameters change them one after the other and analyze the effect of this measure on the opening angle of the spray jet by analyzing the image of the spray jet.
- control system issues an alarm message (locally and / or at a remote location) in cases where a change in the spray parameters does not lead to the desired success and at the same time suggests a possible measure. Possible suggested measures can consist, for example, of cleaning or replacing nozzles. In addition, it is preferably provided that the control system switches off the spraying process in such cases.
- This monitoring method for the opening angle of a spray jet can be used, for example, when painting surfaces and in particular when applying underbody protection to vehicles.
- As a measure to correct the opening angle of the spray jet in the case of applying underbody protection, it is particularly appropriate to vary the temperature of the soil protection composition to be applied in the area of the spray head. The resultant change in the viscosity of the soil protection composition has a particularly pronounced effect on the opening angle of the spray jet, so that a correction can easily be made by this measure.
- Figure 1 shows the video image of a steel sheet that has been phosphated with zinc phosphating.
- the phosphate layer was arbitrarily damaged in order to simulate phosphating errors.
- the grid shown represents the division into individual picture elements for which the differences in the average brightness values are to be determined according to the invention.
- the image section has a size of approximately 11 x 8 cm.
- Figure 2 shows the result of the difference determination of the average brightness values of neighboring picture elements along a line lying horizontally in the picture.
- the diagram in the upper half of the picture corresponds to the undamaged phosphated sheet in the upper half of Fig. 1, the diagram in the lower half of the picture Image of the damaged phosphate layer in the lower half of Fig. 1.
- the differences in the brightness values of neighboring picture elements along horizontal lines in Fig. 1 are shown as horizontal lines in Fig. 2.
- the individual horizontal lines of the picture elements in Fig. 1 correspond to the individual lines in Fig. 2.
- Fig. 3 shows the video image of a spray jet for applying underbody protection to a vehicle body in the lower half of the image.
- the video recording was optically filtered in order to make the limits of the spray jet and its inhomogeneities more clearly recognizable.
- the grid shows the selected picture elements, whereby the entire picture section has a size of approximately 16 x 12 cm.
- the upper half of the figure shows the result of the determination of the differences in the average brightness values of adjacent picture elements, each along a horizontal line. Lines on top of each other in the upper half of the picture correspond to the rows of picture elements on top of each other in the lower half of the figure.
- the outer boundary of the spray jet and inhomogeneities within the spray jet can be recognized by particularly large differences in the brightness values of adjacent picture elements.
- the homogeneity of the spray jet can be assessed in this way. It can also be checked whether the opening angle of the spray jet changes over time. In this way, one compares video recordings taken at different times with one another and checks whether the edge of the spray jet on the individual recordings falls into corresponding picture elements.
- the spray jet angle can be determined directly from the representation of the differences in the brightness values of adjacent picture elements in accordance with the upper half of FIG. 3. In this way, the following algorithm can be used: Are the boundary lines of the spray jet described above by the two line equations
- the opening angle alpha of the spray jet results from the formula:
- Fig. 4 shows the application of this method to the spray jet according to Fig. 3.
- the upper part of Fig. 4 shows schematically at which point in the individual lines of Fig. 3 (top) the outermost major differences the brightness values of neighboring picture elements are determined. These correspond to the boundary line of the spray jet. Below that for each of the two boundary lines of the spray jet, the straight line equation is given and the opening angle of the spray jet is calculated from this using vector algebra. In this example it is 47 °.
- Size of the image section each about 11 x 8 cm.
- FIG. 1 Graphical representation of the differences in the brightness values of the neighboring picture elements in Fig. 1.
- the upper and lower halves of the Fig. Correspond to each other. Lines on top of each other in Fig. 2 correspond to rows of image elements on top of each other in Fig. 1.
- Fig. 4 Schematic position of the respective outer significant difference values of neighboring picture elements in Fig. 3, above, which indicate the limitation of the spray jet. below: calculation of the opening angle of the spray jet
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Abstract
Description
Claims
Priority Applications (8)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CA002346781A CA2346781A1 (en) | 1998-10-09 | 1999-09-30 | Method for monitoring a two-dimensional or three-dimensional distribution process |
ROA200100372A RO120508B1 (ro) | 1998-10-09 | 1999-09-30 | Metodă de control al unui proces de distribuţie superficială sau spaţială |
PL99347064A PL347064A1 (en) | 1998-10-09 | 1999-09-30 | Method for monitoring a two-dimensional or three-dimensional distribution process |
SK476-2001A SK4762001A3 (en) | 1998-10-09 | 1999-09-30 | Method for monitoring a two-dimensional or three-dimensional distribution process |
BR9915023-9A BR9915023A (pt) | 1998-10-09 | 1999-09-30 | Processo para o controle de uma distribuição plana ou espacial |
HU0104024A HUP0104024A3 (en) | 1998-10-09 | 1999-09-30 | Method for monitoring a two-dimensional or three-dimensional distribution process |
AU22547/00A AU2254700A (en) | 1998-10-09 | 1999-09-30 | Method for monitoring a two-dimensional or three-dimensional distribution process |
SI9920079A SI20441A (sl) | 1998-10-09 | 1999-09-30 | Postopek za kontrolo površinske ali prostorske porazdelitve |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19846530.0 | 1998-10-09 | ||
DE19846530A DE19846530A1 (de) | 1998-10-09 | 1998-10-09 | Verfahren zur Kontrolle einer flächigen oder räumlichen Verteilung |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2000022574A1 true WO2000022574A1 (de) | 2000-04-20 |
Family
ID=7883916
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP1999/007244 WO2000022574A1 (de) | 1998-10-09 | 1999-09-30 | Verfahren zur kontrolle einer flächigen oder räumlichen verteilung |
Country Status (15)
Country | Link |
---|---|
CN (1) | CN1322332A (de) |
AR (1) | AR020752A1 (de) |
AU (1) | AU2254700A (de) |
BR (1) | BR9915023A (de) |
CA (1) | CA2346781A1 (de) |
CZ (1) | CZ20011247A3 (de) |
DE (1) | DE19846530A1 (de) |
HU (1) | HUP0104024A3 (de) |
PL (1) | PL347064A1 (de) |
RO (1) | RO120508B1 (de) |
SI (1) | SI20441A (de) |
SK (1) | SK4762001A3 (de) |
TR (1) | TR200100663T2 (de) |
WO (1) | WO2000022574A1 (de) |
ZA (1) | ZA200102839B (de) |
Families Citing this family (8)
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DE102007057018A1 (de) * | 2007-11-23 | 2009-05-28 | Volkswagen Ag | Verfahren und Vorrichtung zur Qualitätskontrolle einer Oberfläche |
WO2014102567A1 (en) * | 2012-12-27 | 2014-07-03 | L'oréal | Method for determining make-up removal efficiency |
DE102016104134A1 (de) * | 2015-11-10 | 2017-05-11 | Polyplan-GmbH Polyurethan-Maschinen | Verfahren und Anordnung zum Aufbringen von flüssigen oder pastösen Stoffen |
IT201600089389A1 (it) * | 2016-09-02 | 2018-03-02 | Sacmi | Impianto, e relativo processo, per la smaltatura di articoli igienico sanitari |
CN107192714B (zh) * | 2017-06-01 | 2020-03-27 | 首钢集团有限公司 | 一种测量浸入式水口堵塞程度的方法及*** |
EP3715779B1 (de) * | 2019-03-29 | 2022-10-19 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Verfahren und vorrichtung zur bestimmung von verformungen an einem objekt |
WO2022107316A1 (ja) * | 2020-11-20 | 2022-05-27 | 昭和電工マテリアルズ株式会社 | 水膜の評価方法及び防曇剤の評価方法 |
CN118010637B (zh) * | 2024-04-09 | 2024-06-07 | 江苏迪莫工业智能科技有限公司 | 一种生产工具用螺母检测***及其检测方法 |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4958374A (en) * | 1988-03-04 | 1990-09-18 | Toshiba Machine Company, Ltd. | Method of checking pattern and apparatus therefor |
-
1998
- 1998-10-09 DE DE19846530A patent/DE19846530A1/de not_active Withdrawn
-
1999
- 1999-09-30 CA CA002346781A patent/CA2346781A1/en not_active Abandoned
- 1999-09-30 BR BR9915023-9A patent/BR9915023A/pt not_active IP Right Cessation
- 1999-09-30 CZ CZ20011247A patent/CZ20011247A3/cs unknown
- 1999-09-30 AU AU22547/00A patent/AU2254700A/en not_active Abandoned
- 1999-09-30 CN CN99811838A patent/CN1322332A/zh active Pending
- 1999-09-30 TR TR2001/00663T patent/TR200100663T2/xx unknown
- 1999-09-30 WO PCT/EP1999/007244 patent/WO2000022574A1/de active Application Filing
- 1999-09-30 HU HU0104024A patent/HUP0104024A3/hu unknown
- 1999-09-30 SK SK476-2001A patent/SK4762001A3/sk unknown
- 1999-09-30 SI SI9920079A patent/SI20441A/sl unknown
- 1999-09-30 RO ROA200100372A patent/RO120508B1/ro unknown
- 1999-09-30 PL PL99347064A patent/PL347064A1/xx unknown
- 1999-10-08 AR ARP990105099A patent/AR020752A1/es unknown
-
2001
- 2001-04-05 ZA ZA200102839A patent/ZA200102839B/en unknown
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4958374A (en) * | 1988-03-04 | 1990-09-18 | Toshiba Machine Company, Ltd. | Method of checking pattern and apparatus therefor |
Non-Patent Citations (2)
Title |
---|
FERNANDEZ C ET AL: "VISION SYSTEM FOR ON-LINE SURFACE INSPECTION IN ALUMINUM CASTING PROCESS", PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON INDUSTRIAL ELECTRONICS,CONTROL, AND INSTRUMENTATION (IECON'93),US,NEW YORK, IEEE, vol. 3, 15 November 1993 (1993-11-15) - 19 November 1993 (1993-11-19), pages 1854-1859, XP000437516 * |
WAHL, F.M.: "Digitale Bildsignalverarbeitung", 1984, SPRINGER-VERLAG, BERLIN, XP002128889 * |
Also Published As
Publication number | Publication date |
---|---|
ZA200102839B (en) | 2002-07-05 |
HUP0104024A3 (en) | 2002-04-29 |
AR020752A1 (es) | 2002-05-29 |
DE19846530A1 (de) | 2000-04-13 |
CZ20011247A3 (cs) | 2001-09-12 |
SI20441A (sl) | 2001-06-30 |
BR9915023A (pt) | 2001-08-14 |
TR200100663T2 (tr) | 2001-08-21 |
SK4762001A3 (en) | 2001-11-06 |
HUP0104024A2 (hu) | 2002-03-28 |
RO120508B1 (ro) | 2006-02-28 |
AU2254700A (en) | 2000-05-01 |
CA2346781A1 (en) | 2000-04-20 |
CN1322332A (zh) | 2001-11-14 |
PL347064A1 (en) | 2002-03-11 |
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