System and method for selectively and locally treating a surface of a component, in particular by deposition of a material - Patents.com

Abstract

1. A method for selectively and locally processing a surface of a part, comprising: providing a part having a treatment surface, the surface being defined by a direction P and a direction Q; acquiring three-dimensional shape measurement data from the treatment surface to obtain a set of three-dimensional data F1 associating a height to each point in a plane PQ with respect to the treatment surface; digitally processing the set F1 for the purpose of subtracting the curvature to obtain a re-processed set of three-dimensional data F2; digitally processing the data in set F2 to assign to each point on the surface a first binary value or a second binary value depending on at least one criterion related to the height of the point on the surface; obtaining a set of binary data F3 relating to the treatment surface; and selectively and locally processing the surface using the set of binary data F3, performing the surface treatment only at points on the surface where the binary data has the first or second binary value.

Description

[Technical field]

[0001] The present invention relates to a method for selectively and locally treating the surface of a part through the deposition of a material, more particularly through inkjet printing. More particularly, the invention relates to a surface treatment method comprising a step of selective and local decoration by ink deposition in areas determined during the execution of the method itself according to their relief. This method can be used for the decoration of parts whose surfaces have shapes with regular or irregular reliefs, such as grains, seams, seals, logos, patterns, edges, etc. [Background technology]

[0002] Techniques for treating the surface of parts through the deposition of material are known, for example inkjet printing. These techniques can be used to print images on large-sized surfaces, these surfaces having dimensions, for example, of the order of a few tens of centimetres up to one or two metres. The printing can be carried out by inkjet printheads arranged at the end of the arms of a multi-axis robot.

[0003] Such a system is described in US 2015 / 0042716 (Heidelberger Druckmaschinen AG). Images can be printed by inkjet on curved surfaces such as car bodies. Similar systems are described in US 2014 / 0063096 (Heidelberger Druckmaschinen AG) for printing on car bodies and in US 2013 / 0314460 (Exatex) for printing on car windows. EP 2873496 (ABB Technology AG) proposes a similar system in which an inkjet printhead is connected to a six-axis robot arm by means of piezoelectric actuators capable of performing controlled movements.

[0004] These systems generally include a system for acquiring the overall shape (flat or curved) of the part on the path that will be the path of the inkjet printhead. They are able to print images on this flat or curved surface. However, these systems are not suitable for applications for which they were not designed, namely other applications of selective treatment of the surface in areas resulting from local relief aspects, for example bosses, creases, grooves or other aspects. Such surface aspects can be found, for example, on the surface of natural or artificial leather and can be caused by grains or seams of the leather. Even in the case of parts obtained by molding in the same mold, the position and shape of these local relief aspects cannot be reproduced exactly from one part to another. During the decoration of such surfaces by printing, the lack of reproducibility of the surface relief can lead to inaccurate placement of the image.

[0005] Prior art systems can print images on such surfaces with local aspects by ignoring the local aspects of the surface based on the global shape of the part previously acquired. This printing may be accurate enough if the printed image does not need to be superimposed on the local relief. On the other hand, prior art systems cannot selectively process these local surface aspects. As an example, they cannot selectively deposit ink at the seam lines of a leather surface or selectively color the grain lines (i.e. the recesses between two grains) of a leather surface. The term "leather surface" refers here to the surface aspects and not to a material whose chemical properties are not important for the problem at hand. This leather surface can be an artificial leather surface, such as a plastic material, common in the field of automobile dashboards.

[0006] The problem that the invention seeks to solve is to propose a system for treating flat or curved surfaces, which allows selective treatment of the surface, for example selective decoration, of areas of said surface that are imprinted in relief on said surface (either as depressions or bumps), which system must have as low an offset as possible in the direction parallel to the plane of the substrate, and as low an offset as possible in the direction perpendicular to the plane of the substrate. Summary of the Invention

[0007] A first object of the invention is to provide a method for selectively and locally treating the surface of a component, comprising the steps of: (a) providing a part having a surface to be treated, said surface being defined by a direction P and a direction Q, said surfaces P and Q may have curvature; (b) acquiring three-dimensional shape measurement data from the surface to be processed to obtain a set of three-dimensional data F1 relating a height to each point in a plane PQ with respect to the surface to be processed; (c) digitally processing this set of data F1 for the purpose of subtracting said curvature to obtain a set of reprocessed three-dimensional data F2 relating to the surface being processed; (d) digitally processing this set of data F2 to assign to each point on the surface a first or a second binary value depending on at least one criterion related to the height of said point on the surface, to obtain a set F3 of binary data relating to the surface to be processed; (e) selectively and locally processing said surface using said set of binary data F3, performing said surface processing only at points on said surface where said binary data has said first or said second binary value; Includes.

[0008] Typically, the surface to be treated has contoured surface elements.

[0009] In one embodiment, the three-dimensional shape measurement data is obtained from a series of linear scans with scan lines parallel to the direction P, with two adjacent scan lines spaced at a fixed interval, the fixed interval being preferably less than 100 μm, more preferably less than 90 μm.

[0010] In step (c), at least one digital filtering operation may be performed on the data, for example to eliminate anomalous points.

[0011] In a particular embodiment, said criterion relating to the height of the surface points in step (d) assigns the same binary value to all points situated between a minimum height and a maximum height.

[0012] In another particular embodiment, step (d) is repeated to obtain a data set F3' having a criterion related to the height of the points of the surface different from that used to generate said data set F3, and two processing steps are performed according to step (e), i.e. said processing steps can be of the same or different nature for each set of data sets F3 and F3'.

[0013] In another embodiment, which can be combined with all others, data set F3 is reprocessed to remove isolated points from the surface treatment, to remove adjacent areas from the surface treatment that do not reach a certain surface area, to enlarge adjacent areas of the surface treatment, to round angles of areas of the surface treatment, or to remove holes of a size smaller than a certain number of points in an area of ​​the surface treatment.

[0014] Typically, said surface treatment is the same for all points where said binary value takes on said first or second value.

[0015] The surface treatment may include depositing a material, such as depositing an ink, or removing a material, such as drilling a hole, or chemically modifying the surface, such as providing energy that can crosslink the surface.

[0016] In another method, a first surface operation is performed for points where the binary data takes on the first binary value, and then a second surface operation is performed for points where the binary data takes on the second binary value.

[0017] The part typically comprises: - Automotive cover parts, such as the cover parts of the passenger compartment of a car, especially the cover parts of the dashboard and doors; - Parts made of natural or artificial leather, in particular leather products or furniture parts or parts used in the manufacture of visible parts of leather products or furniture parts; - parts having a textured surface, - Metal or plastic parts being manufactured in contact with the surfaces of the mould, The compound is selected from the group formed by:

[0018] Another object of the invention is the use of the method according to the invention for the decoration of parts having regular or irregular surface relief, said surface relief being able to correspond in particular to grains, seams, seals, edges, markings.

[0019] Yet another object of the invention is an apparatus comprising: A robot comprising at least one gripping arm equipped with a laser profilometer and capable of acquiring 3D shape measurement data, and at least one surface treatment tool. a computer in communication with the robot, the laser profilometer, and the at least one surface treatment tool and configured to control operation of the robot, the laser profilometer, and the at least one surface treatment tool.

[0020] The apparatus is configured and capable of implementing the method for selectively and locally treating a surface of a component according to the invention. Advantageously, the computer is configured to carry out the digital data processing of steps (c) and (d). When the surface treatment is a treatment by deposition of material, the surface treatment tool is advantageously an inkjet printhead.

[0021] A final object of the invention is a computer program comprising program code instructions for carrying out the steps of the method according to the invention when it runs on a computer intended and capable of controlling the operation of the device according to the invention. [Brief description of the drawings]

[0022] Figures 2 to 7 show different embodiments of the present invention and are not intended to limit the scope of the invention. [Figure 1] 1 shows a schematic representation of a measuring head of a surface treatment device according to the invention, the components of which are part of the prior art. [Diagram 2] FIG. 2 shows diagrammatically a surface treatment device according to the invention which makes it possible to carry out the method according to the invention for the selective and local treatment of a surface. [Diagram 3] 3 is a photograph of a cover part of a dashboard of a car, which has three parallel false seams, two of which are treated by printing with the method according to the present invention, each of which has a length of about 4-6 mm and a width of about 1 mm. [Figure 4]FIG. 4 shows four steps of the method according to the invention (applied to a dashboard cover part similar to that shown in FIG. 3): acquisition of the surface relief by a laser beam scanning in a direction perpendicular to the false seam line (direction Q) and then displaced in a direction parallel to said line (direction P) (FIG. 4(a)); the raw surface relief in the direction perpendicular to said seam line (direction Q) (curve (1)) and regression by subtraction of the curve (FIG. 4(b)); reconstruction of a three-dimensional image of the analyzed surface from the series of acquisitions (gray levels representing the height in the direction perpendicular to the plane QP) (FIG. 4(c)); and a binary image (black and white) of important aspects of the surface identified in black ink for selective decoration (FIG. 4(d)). [Diagram 5] Figure 5 shows a curve similar to curve (2) in Figure 4(b) and also shows three pseudo seam lines on the dashboard. Figures 5(a), 5(b) and 5(c) then show three-dimensional data from three different processes aimed at obtaining a binary image of the surface that defines the area to which the surface treatment is applied. [Figure 6] Figure 6 shows an optical microscope photograph of four pseudo-seam lines (these lines are similar to the lines forming the two perimeter lines in Figures 3 and 4(c)) after decoration with grey ink using the method according to the invention. Each of the pseudo-seam lines has a length of about 4 mm. In this example, the ink has been deposited in the areas of high relief. [Figure 7] Figure 7 shows another example of a part whose surface can be selectively and locally treated by deposition of material by inkjet using the method and device according to the invention. Figure 7(a) shows a reconstruction of a three-dimensional image of the surface analyzed by a series of acquisitions (gray levels represent the height in the direction orthogonal to the plane QP). Figure 7(b) shows a binary image of the important aspects of the surface identified for the purpose of selective decoration. The ink is deposited in the areas of depressions (reliefs of the reliefs). [Figure 8]Figure 8 shows yet another example of a part whose surface can be selectively and locally treated by deposition of material by inkjet using the method and device according to the invention. Figure 8(a) shows a reconstruction of a three-dimensional image of the surface analyzed by a series of acquisitions (gray levels represent height in the direction orthogonal to the plane QP). Figure 8(b) shows a binary image of important aspects of the surface identified for the purpose of selective decoration. The ink is deposited in areas of depressions (reliefs) as in Figure 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The inventors have realized that printing images on uneven surfaces with surface features may not be a satisfactory solution to the problem. The term image printing here refers to a method of printing a given image on a surface and possibly resizing it in space according to the local shape. According to the invention, selective surface treatment (surface printing represents a specific case) is performed only in selected areas, depending on the presence of specific surface features, taking into account their height and / or their depth and / or their exact shape.

[0024] In the first step of the method according to the invention, a part is provided having a surface to be treated. The surface to be treated of this part may typically be curved along a major axis and / or along a minor axis that may be orthogonal to said major axis. Said major and minor axes may be straight or curved. The surface to be treated is typically a curved section of the part, for example a longitudinal section that is substantially parallel to the length of the part. In another embodiment, the surface to be treated is not curved but is substantially flat.

[0025] The treated surface of the part usually comprises relief elements which may extend according to any geometric arrangement or shape over all or part of the treated surface. These relief elements may be decorative elements.

[0026] By way of example, the relief elements may include bumps or depressions. They may be arranged in narrow, elongated lines or, conversely, may extend over a significant portion of the surface to be treated. By way of example, the relief elements may correspond to false seams, and / or grain in the style of leather, and / or "alligator skin", or any kind of stitching or relief obtained by any method (imprinting, which may be performed by cold or heat, and / or embossing, which may be performed by cold or heat), or natural relief.

[0027] The part is advantageously fixed in a determined orientation in space. Advantageously, it is arranged on a support. If the surface to be treated has a long axis, the part is advantageously oriented so that this long axis is approximately horizontal.

[0028] Alternatively, the part is not fixed but is displaced during the execution of at least one of the following steps of the method. For example, it can be fixed to a movable carriage displaceable according to a path that may be straight or not, and / or that can be tilted in one or more directions, and / or that can rotate about at least one axis. If the part has such a major axis, it can rotate about that major axis, and / or if it has such a minor axis, it can rotate about that minor axis, and / or it can undergo any other type of rotation, tilt or displacement in space.

[0029] In any case, when a large number of parts that are assumed to be identical have to be processed (e.g. from the same production series, e.g. from the same plastic mould), it is important that the supports allow reproducible positioning. If applicable, specific supports should be manufactured for each type of part.

[0030] In a second step, profilometry data are acquired from the surface to be treated. These profilometry data are three-dimensional data reconstructed from a series of two-dimensional linear scans (herein called profilometry lines) using the laser beam. These profilometry lines are parallel to each other and the spacing between two adjacent lines is advantageously constant.

[0031] These shape measurement data must firstly represent the overall three-dimensional shape of the surface to be treated. They must also be able to represent or determine the decorative elements with sufficient three-dimensional resolution. This minimum resolution depends on the shape of the surface to be treated, the nature and shape of the decorative elements, the length and depth scales of the decorative elements and the required accuracy of the surface treatment.

[0032] This second step can be carried out, for example, using the measuring head of a laser scanner fixed to a robot arm and performing one or several scan paths on the surface to be treated. These paths are advantageously parallel to the length direction of the part (here indicated by the letter P). Depending on the dimensions of the area of ​​the surface to be treated, the data acquisition can be carried out in one or several paths. More specifically, each path usually makes it possible to acquire data on an area having a certain width Q in a direction orthogonal to the scan line. Depending on the length of the surface to be treated, the width of the area to be treated must therefore be subdivided into several sub-areas, each of which is subject to at least one scan path. These sub-areas can partially overlap. Usually, the data acquisition is carried out via a succession of individual acquisitions of a linear profile in the direction Q, two successive individual acquisitions being spaced by the same distance in the direction P. The three-dimensional profile is therefore built up from a succession of two-dimensional acquisitions (geometry lines).

[0033] A first pass in the direction P allows the overall shape of the surface to be treated to be determined, while a second pass allows finer resolution data of the surface to be treated to be obtained. At least during this second pass, the distance between the measuring head and the surface advantageously remains constant or barely changes (advantageously at most ±5, preferably at most ±3 mm, more preferably at most ±2 mm) and the direction of the laser beam relative to the surface is also constant. For this reason, in the case of curved parts, it is advantageous to fix the measuring head to a 5- or 6-axis robot arm. If the surface of the part to be treated has a length direction, it is advantageous for the scanning path to be parallel to this length direction. Advantageously, a single scanning path is performed to analyze an area with a given width Q. In an advantageous embodiment, for highly curved parts and / or for lines P and / or Q that are not straight, it is advantageous not to change the height z of the measuring head during the scan in the direction Q and / or to change the height z of the measuring head during the scan in the direction P in order to follow the curvature of the lines P and / or Q. In this case, it is often desirable to restrict the data acquisition area to an area that does not require such adjustments and then define another data acquisition area adjacent to the first one. In other words, it may be preferable to limit the number of independent movements of the robot arm during the measurement head scan. The same applies to the surface treatment tool carried by the robot arm in the fifth step.

[0034] This second step involves the generation of a first file of three-dimensional data of the surface of the part, called here F1. It is constructed using the data corresponding to the shape measurement lines taken successively on line P and obtained in direction Q.

[0035] In a third step, the profilometry data is digitally processed and analyzed. This processing can include several individual steps. It can include digital filtering. This filtering can be performed on each acquired profilometry line and / or on the 3D profile reconstructed from the profilometry lines.

[0036] In the framework of this filtering, anomalous points can be removed and / or the surface can be smoothed. These two operations can usually be performed using known digital techniques. More specifically, the background is subtracted to overcome the curvature of the part in the direction Z (i.e. orthogonal to the direction of the scan P). This step creates a second file of three-dimensional data of the surface of the part, which we call F2.

[0037] In an embodiment of this third step, first, in a first sub-step, a digital smoothing is performed on each shape measurement line (e.g. by a suitable exponential filter), then the low frequencies are advantageously removed (e.g. by a suitable high-pass filter), and then the profile is corrected (e.g. via linear regression). These different processes can be reordered, but the order shown is preferred.

[0038] Then, in a second sub-step, the 3D profile is processed to remove anomalous points, for example via plane regression (calculating the mean plane), which can include, for example, filtering points by standard deviation and filtering points that are too far from the plane.

[0039] The fourth step has the purpose of identifying or localizing the areas to be treated of the surface to be treated. These areas are defined by specific relief characteristics. Thus, the relief of the surface to be treated determines the areas to which the surface treatment is to be applied. This step is essential for the method according to the invention. Indeed, for example in the case of printing on a surface, the printing method according to the invention does not involve printing a pre-established image on the surface. In the framework of the method according to the invention, the image is not provided (for example in the form of a file), but the areas of the surface to be treated by the surface treatment means selected later are determined during the method itself according to the relief of the surface. In other words (and in the example of surface treatment by inkjet printing), the fine shape of the image to be printed on the surface depends on the surface itself and is not fixed beforehand.

[0040] The purpose of this fourth step is to generate a binary image (file F3) of the surface to be processed, which contains binary information for each point in the plane QP. For each point, said binary information indicates whether a surface processing should be performed or not.

[0041] Typically, the areas to be treated are low relief (i.e., depressions) or high relief (i.e., bosses), or both. Then, minimum and maximum height thresholds are adjusted (the heights correspond to the "gray levels" of the image of the surface), and points that fall between the minimum and maximum thresholds are defined as "black" points (i.e., surface treatment is performed), while points above the maximum and below the minimum threshold are made "white" (i.e., no surface treatment is performed). This threshold determination (e.g., deviation between maximum and minimum thresholds) can be the same for different similar parts of the same series, especially parts from the same mold.

[0042] In a fifth step, the treatment of the surface to be treated is carried out. This treatment usually involves the deposition of a material. This surface treatment is usually carried out via a surface treatment tool fixed to a robotic arm and performing one or more scanning paths over the surface to be treated, preferably along the trajectory used for the acquisition of the geometric measurement data of the part. This tool can be an inkjet printhead capable of depositing an ink. The term "ink" here means any liquid preparation capable of forming a solid deposit on a solid substrate after drying and / or crosslinking. The term therefore includes not only the inks typically used in inkjet printers, but also varnishes (pigmented or non-pigmented, opaque or transparent) and other products.

[0043] This treatment can be carried out in one or several routes and can use one or several inks, for example pigmented inks and a transparent or translucent varnish deposited on top of the pigmented inks, which can have different functions, for example protection against scratches, or modifying optical properties (anti-reflection, aesthetic functions such as changing the brightness or the perceived color), or modifying the feel, or anti-smudge.

[0044] According to an advantageous embodiment, if several inks are used during the fifth step, a different printhead is used for each ink.

[0045] According to another advantageous embodiment, which can be combined with each of the other advantageous embodiments and their alternatives, a printing system (including a robot, a system for determining the area to be printed, and a surface treatment tool) is used, the accuracy of which, i.e. the deviation of the positioning of said treatment (e.g. the deviation of the positioning of the print) with respect to the shape of the area to be treated, does not exceed the value of X. This value of X is advantageously less than 100 μm, more advantageously less than 90 μm. Advantageously, a high-resolution print head is used with a spacing of at least 360 nozzles per inch, such a head can, for example, include a total of 512 nozzles.

[0046] As shown above, according to an essential feature of the invention, the fine shape of the image printed on a surface depends on the surface itself. The method is therefore able to identify the area of ​​the surface to be printed. By way of example, if the part is an element of a car dashboard, which has an artificial or real seam and needs to be colored, the method recognizes the accidental absence of a seam and does not color the missing threads in that length. In this example, it is well shown that the printing method does not involve the printing of a predefined image, but rather the selective surface treatment (here coloring) of an area whose identification is part of the method itself.

[0047] The method according to the present invention will now be described with reference to the drawings.

[0048] FIG. 1 shows a schematic representation of a measuring head that can be used in a surface treatment device according to the invention. It is a typical optical scanning profilometry method without mechanical contact with the surface to be analyzed. More precisely, the measuring head 1 comprises a laser source 2 (usually a laser diode) that emits a laser beam, called incident beam 3, that is directed towards the surface 5 to be analyzed. A sensor 6 detects the reflected beam 7. The device typically comprises an optical system 8, which includes at least one lens through which the reflected beam passes. This measuring head takes a line 4 of length Y1 parallel to the direction Y and continues to take one-off measurements spaced apart by a distance ΔY between two adjacent points. This distance is usually constant. For each point in the Y direction, a height in the vertical direction Z is detected and a profile of the height of the surface is obtained on the line scanned in the Y direction. This line is hereafter referred to as the profilometry line. The measuring head or the surface is then displaced by a distance ΔX in a direction designated as X, which is typically perpendicular to Y and typically corresponds to the length direction of the surface, and a profile is obtained on this line as described above. Thus, a file F1 can be obtained for the surface points on the analyzed area, each point being characterized by its three coordinates X, Y, Z. This technique for 3D shape measurement by laser scanning is known to the person skilled in the art and will not be described in detail.

[0049] Figure 2 shows diagrammatically an apparatus 10 according to the invention, which makes it possible to carry out the method according to the invention. The apparatus comprises a robot mounted on a body 17. In this example, it is a robot with five axes, the axes being marked with the letters A1 to A5. The articulated arm 15 of the robot is provided at its end with a gripping arm 16 to which the measuring head 1 can be attached, and a surface treatment tool. The part 12 to be treated rests on a support 11, which allows a reproducible and identical positioning of presumably identical parts of the same series. The surface 4 to be treated of the part 12 faces upwards. Here, it is a curved part. The directions P and Q shown in this figure are explained in relation to figure 3 below. The apparatus 10 is controlled by a programmable computer (not shown).

[0050] The term "computer" as used herein includes in particular computers and programmable (logic) controllers, said computer being intended and capable of controlling the activity of the device 10 according to the invention, and for this purpose it includes in particular a computer program comprising program code instructions for carrying out the steps of the method according to the invention, when said program runs on said computer.

[0051] The surface treatment tool can be integrated into the measuring head or can be housed separately from the box of the measuring head and can then be engaged with the measuring head. In another embodiment not shown, the gripping arm 16 grips the measuring head and the surface treatment tool alternately, knowing that they are deposited in a receiving station when not in use.

[0052] FIG. 3 shows a photograph of a part treated by the method according to the invention, here a cover part for a dashboard of a car. This part is composed of an area of ​​a false seam that runs parallel to the length of the part. More precisely, the artificial seam of the part is composed of two relief surfaces, i.e. a central seam 31 simulating the connection between two parts 30', 30" of the part with parallel edges, and two peripheral seams 32', 32" parallel to said central seam 31. In the peripheral seams, the seam appears at a higher height relative to the plane of the part than in the central seam. The line segment Q represents the scan of the laser beam of the shape measuring instrument 1 at each point selected on the line P corresponding to said central seam 31. This laser beam is shown in FIG. 4(a), which is a photograph of a similar part to that of FIG. 4 (but in darker colors). In the lower part of the image, a ruler calibrated in centimeters is shown, placed on a part of the surface of the part.

[0053] Thus, in a second step of the method according to the invention, it is possible to obtain a three-dimensional data file F1, identify the relief in the plane of the surface to be treated and quantify for each point in this plane the height or depth relative to said plane.

[0054] Figure 4(b) shows the raw form measurement curve (curve (1)) corresponding to line Q obtained at a point on line P and the same form measurement curve after digital correction (curve (2)). This curve (2) represents the change in surface height relative to the base level corresponding to the curved surface of the part. The two peripheral seams 42', 42" and the central seam 41 are identified in the raw curve (1). After digital correction (curve (2)), the two peripheral seams 52', 52" and the central seam 51 appear on a straight plane.

[0055] Fig. 4(c) shows a reconstructed image from a shape measurement performed successively on several parallel line segments Q on a line P of a certain length. This image is obtained after correction of the shape measurement line, i.e. from a shape measurement line like the curve (2) shown in Fig. 4(b). The data has also been filtered. Fig. 4(c) thus shows the data of file F2 at the end of the third step of the method according to the invention, the grey levels representing the height with respect to the base level mentioned above. This shows an artificial seam in the 3D coding.

[0056] If it is desired to process only the peripheral seams of the surface to be treated, in particular through the deposition of material such as inkjet printing, the three-dimensional data of file F2 can be subjected to a digital processing which removes the central seam. This digital processing can include a digital filter which takes into account the height relative to the plane of the surface and / or takes into account the surface morphology. Thus, at the end of the fourth step of the method according to the invention, a file F3 of reprocessed three-dimensional data is obtained, which represents a binary image of the surface to be treated.

[0057] FIG. 4(d) shows such a binary image (i.e. black and white) obtained from the three-dimensional data of file F2 by suitable filtering, where the filtering is designed to remove the central seam 31 that is not to be treated by surface treatment. Lines 72', 72" correspond to the seams 32', 32". This binary image corresponds to a file F3 of binary data and indicates for each elementary point whether a surface treatment (usually by projecting drops of ink or varnish) needs to be performed. The points that make up this file F3 are preferably defined in a two-dimensional space.

[0058] As an intermediate conclusion, the height curve obtained with the shape measurement line, as described above (curve (1) in Figure 4(b)), is input into the creation of a file F1, which contains, for each point of the plane QP, the height orthogonal to this plane. After correction of the data and various digital filtering operations, a file F2 is obtained and in this way the surface can be represented with a reconstructed image in which the height is represented by grey levels, as in Figure 4(c).

[0059] The method according to the invention does not directly use this file F2 to carry out a surface treatment through the deposition of material, but rather through the projection of droplets of ink or varnish, so that the file F2 containing the three-dimensional data with height values ​​for each point in the plane QP must be converted into a file F3 which associates to each point in the plane QP not a height but a binary value indicating the presence or absence of a surface treatment at this point.

[0060] This filtering method, which derives the file F3 of binary data and which represents the fourth step of the method according to the invention, will now be described in more detail.

[0061] Figure 5 shows the shape measurement line after digital correction, similar to curve (2) in figure 4(b). The horizontal axis represents the position on the line segment Q (figure 3) and the vertical axis represents the height relative to the plane QP. Two peripheral seams 52', 52" and a central seam 51 are distinguished.

[0062] Here, using Figure 5 (in three options (a), (b) and (c)), a threshold Z is determined to define the area where the surface treatment is applied. max , Z min This thresholding is described here for a single shape measurement line, and while it is possible to proceed line by line as well, in practice it is advantageous to perform this operation using all the 3D data in file F2.

[0063] This transformation can be performed by appropriate filtering, which must be adapted to each type of surface topography.

[0064] By way of example, the principle of such filtering is illustrated in FIG. 5 for the case of false seams. It involves identifying the aspects of the surface to be processed. This can be done via symmetric or asymmetric (or one-sided) clipping. FIGS. 5(a) and 5(b) show two different symmetric clippings that do not have the same objective. The clipping in FIG. 5(a) aims to identify a central seam 51 for the purposes of its selective surface processing, while the clipping in FIG. 5(b) aims to identify two peripheral seams 52', 52" for the purposes of its selective processing. In the example of FIG. 5(a), a threshold Z max and threshold Z min is fixed to select the area of ​​the center seam 51, and the height value (vertical axis) is min and Z max Any point on the horizontal axis between is black, and the height value is Z max Greater than Z min Any point on the smaller horizontal axis is converted to a binary value of "white". In this way a binary data file is constructed, which is referred to herein as file F3. In a fifth step of the method according to the invention, the points on the shape measurement line that are attributed the value "black" (the name of which is of no importance) are subjected to a selective surface treatment, while the "white" points are not subjected to said selective surface treatment.

[0065] Threshold Z max and threshold Z minThe value of can be determined automatically or manually. This can be done especially for the first part of a series of parts that are supposed to be identical (usually produced in the same mould). In fact, in many cases, such a determination of the threshold value of the corrected profile makes it possible to process a series of parts that are supposed to be identical in a stable and reproducible way. It should be noted that in practice the surfaces of parts from the same mould are not perfectly reproducible and that due to these deviations the surface printing of images by the prior art methods does not give satisfactory results.

[0066] As shown in FIG. 5(b), for example, the threshold Z max A threshold Z' smaller than max Therefore, we can obtain a narrower surface treatment area on the horizontal axis. This is shown in Figure 5(c), where the dotted box has a lower threshold Z than the solid box. max Represents the width of the area obtained by

[0067] In the examples of FIGS. 5(b) and 5(c), one may choose to specify the areas of interest 52′, 52″ with narrower widths. max can be used to artificially expand (extend) the processing area, which is defined, for example, by a certain width. As mentioned above, this clipping and selection of the area of ​​interest can be done manually for certain types of parts. This step may require the temporary generation of a file F3 to display the binary image thus obtained. The threshold value Z max and / or Z min can then be modified to obtain satisfactory results. As mentioned above, typically this configuration can be performed on test parts of a series of parts having the same type of surface topography (e.g. dashboard parts from the same mold).

[0068] According to a particular advantageous embodiment of the invention, additional processing is performed on the binary file in order to improve the quality of the surface treatment, in particular the quality of its positioning. By way of example, black areas can be expanded (enlarged) or, conversely, eroded. Isolated black points (considered as noise) or adjacent areas of black points that do not exceed a certain surface area (expressed as a number of pixels) can be removed. It is also possible to round the angles of black areas. It is also possible to remove holes in black areas. These additional processing performed on the binary file are very advantageous for obtaining high quality surface treatments, such as those required by the automotive industry, the leather industry and other product industries with high demands on surface quality.

[0069] Figure 6 shows four enlarged photographs of seams colored by the method according to the invention using grey ink. The parts are identical to those in figures 3 and 4. Note the extraordinary precision of this surface treatment of the selective and localized surfaces.

[0070] Figure 7 shows another surface that can be treated by the method according to the invention. Here, it is a PVC surface created by embossing a regular relief of "Y"s in the recesses. Figure 7(a) shows the relief represented as grey levels (representation of file F2) and Figure 7(b) shows a binary image (bitmap) corresponding to file F3 from file F2.

[0071] Figure 8 shows another surface that can be treated by the method according to the invention. Here, it is a surface of the "crocodile skin" type, natural or artificial (for example performed by embossing on a PVC surface). Figure 8(a) shows the relief shown in grey levels (file F2) and Figure 8(b) shows a binary image (bitmap) from file F2.

[0072] In the examples of Figures 7 and 8, the surface treatment (here the deposition of ink) has been performed in areas that are recessed relative to the surroundings, but the same method can be applied to treat areas that are elevated relative to the surroundings, as well as the seams of the part shown in Figure 3.

[0073] Please note that in the example part shown in Figure 3, the lines of the parallel seams 31, 32', 32" are not straight. If the scan width Q is sufficiently larger than necessary to cover the perimeter of the peripheral seams 32', 32" and on both sides, the scan by the measuring head 1 can follow a straight line P. If necessary, the longitudinal width of the part can be divided into several line segments. The measuring head 1 follows the straight line P for each line segment and translates in an orthogonal direction between two adjacent line segments. Alternatively, a continuous adaptation of the position of the measuring head 1 during its scan can be provided. However, this significantly increases the amount of digital data to be processed.

[0074] In series-type production with the processing of identical parts, it is advantageous to proceed with a profilometric scan of the surface for each individual part, in order to obtain optimal resolution and precision. This is because, even within a series of parts considered identical, deviations between two parts have a magnitude sufficient to generate visible deviations after decoration. On the other hand, the digital filtering that converts the file F1 into the file F2 can be defined for a series of parts considered identical, since the local variations between two parts are usually smaller than the difference between the relief of the central seam and the peripheral seam. This presupposes in practice that each part can be placed under the head in a reproducible way. A support adapted to each type of part is therefore necessary.

[0075] The method according to the invention can be applied in many sectors of industry and can be used for the decoration of the covering parts of the passenger compartment of land, sea and air vehicles. It can be used, for example, to decorate the surfaces of the dashboards of automobiles and other visible parts used to cover the interior of the passenger compartment of automobiles. It can be used in the leather, leatherwork and furniture industries to decorate natural or artificial leather surfaces, for the most diverse applications. This decoration can be particularly related to the visible seams of the decorated parts, which can be artificial (for example in the case of parts made of plastic materials made of PVC) or functional (in the case of parts made of natural leather). It can also relate to grained surfaces, such as grained surfaces of leather or "crocodile skin" type, or any type of surface relief obtained by technical methods. More generally, it can relate to all surface aspects that represent a lower part of low relief or an upper part of relief.

[0076] The method according to the invention can be carried out using many alternative means.

[0077] By way of example, the area to be treated can be pre-treated before the deposition of the material. This pre-treatment can be, for example, a corona treatment at atmospheric pressure or a treatment by plasma. It can come from a specific treatment tool that becomes the pre-treatment tool carried by the arm of a robot, said tool being displaced over the area to be pre-treated.

[0078] A first layer of material can be deposited that can be deposited over an area larger than the print area calculated by the software. This material can be a bonding or protective layer. For example, it can be transparent, translucent, and possibly colored or opaque.

[0079] The surface treatments may relate to decoration and / or protection. A first decorative surface treatment may for example be carried out in one or several passes and a second protective surface treatment may be carried out in one or several passes. Said first and second surface treatments may be based on the same file F3 or on different files F3. For example, the second file F3 may be obtained by digital extension of the "black" points of the first file F3. The same description may be applied to the different passes of the decorative and / or protective treatments, which may be strictly superimposed, or the second pass may be provided with extension points, or narrowing points, or with a different threshold Z. max , Z min It is possible to use the file F3 obtained using the following steps: 1. Select the file F3 obtained using the following steps. Each of these options allows you to obtain certain decorative effects, especially when using different inks. For this purpose, or more generally, any other digital transformation of the file F3 is possible.

[0080] Also, after one or more passes of surface treatment via material deposition, a new acquisition of profilometric data can be performed and the method according to the invention can be resumed with the next step, which is particularly useful when significant thicknesses of material are deposited during the decoration of the surface.

[0081] In an alternative to the method according to the invention, in the fourth step, rather than creating a file representing a binary image of the surface, a ternary image or something more complex is created. As an example, the data shown in FIG. 5(a) may be processed using a desired threshold Z min and Z max 5(b), the data is processed to select the peripheral seams 52', 52'', with a desired threshold Z min and Z maxIt is possible to perform two processes on the same file. Thus, a first fixed value is assigned to the points of surface treatment of the central seam, a second fixed value to the points of surface treatment of the peripheral seam and a third fixed value to the points of no surface treatment. In a fifth step of the method, the two different surface treatments can be performed in succession with two separate processing tools or with a single processing tool that can selectively perform the two different processes. Such a tool can be an inkjet printhead that can project two different colors of ink.

[0082] In another alternative of the method according to the invention, the shape measurement data are calculated from the images recorded by an optical camera replacing the measuring head 1, which images are analyzed to obtain a binary image of the surface. The surface treatment may also include at least one step of deforming the surface by means not involving the deposition of material, or it may be entirely composed of steps not involving the deposition of material. By way of example, said steps of deforming the surface by means not involving the deposition of material may be the impact of the surface by particles, the irradiation of the surface by a light beam, the local addition of heat, the drilling of holes by a laser beam. These steps of transformation may in particular have the purpose of a chemical transformation of the surface layer of the material (for example by crosslinking or photochemical or thermal hardening) or of its physical transformation (for example by local fusion).

Claims

1. 1. A method for selectively and locally treating a surface of a component, comprising: (a) providing a part having a surface to be treated, said surface being defined by a direction P and a direction Q, said surfaces P and Q may have a curvature; (b) acquiring three-dimensional shape measurement data from the surface to be processed to obtain a set F1 of three-dimensional data relating to each point in a plane PQ with respect to the surface to be processed with a height; (c) digitally processing this set of data F1 for the purpose of subtracting said curvature to obtain a set of reprocessed three-dimensional data F2 relating to the surface to be processed; (d) digitally processing this set of data F2 to assign to each point on the surface a first or a second binary value depending on at least one criterion related to the height of said point on the surface, to obtain a set F3 of binary data relating to the surface to be processed; (e) selectively and locally processing said surface using said set of binary data F3, performing said surface processing only at points on said surface where said binary data has said first or said second binary value; Including, In said step (c), at least one data filtering operation is performed.

2. The method of claim 1, further comprising performing at least one data filtering operation to remove outliers.

3. The method according to claim 1 or 2, further comprising reprocessing said data set F3 to remove outliers from the surface treatment.

4. 4. The method according to claim 1, further comprising reprocessing said data set F3 to remove adjacent areas from the surface treatment that do not reach a particular surface area.

5. 5. The method according to claim 1, further comprising reprocessing said data set F3 to expand the adjacent area of ​​the surface treatment.

6. 6. The method according to claim 1, further comprising reprocessing said data set F3 in order to round angles of areas of surface treatment.

7. 3. The method according to claim 1 or 2, further comprising reprocessing said data set F3 to remove holes of a size smaller than a certain number of points within the area of ​​the surface treatment.

8. 8. The method according to claim 1, wherein the surface to be treated has contoured surface elements.

9. 9. The method according to claim 1, wherein the three-dimensional shape measurement data is obtained from a series of linear scans with scan lines parallel to the direction P, with two adjacent scan lines spaced apart by a regular interval, the regular interval being preferably less than 100 μm, more preferably less than 90 μm.

10. 10. The method of claim 1, wherein the surface treatment is the same for all points where the binary value takes on the first or second value.

11. 11. The method of claim 1, further comprising: performing a first surface operation on points where the binary data takes on the first binary value; and then performing a second surface operation on points where the binary data takes on the second binary value.

12. - repeating step (d) to obtain a data set F3' having a criterion related to the height of the points of the surface different from that used to generate the data set F3, and A method according to any one of claims 1 to 11, characterized in that according to step (e) two treatments are carried out, i.e. said treatments can be of the same or different nature for each of the data sets F3 and F3'.

13. 13. The method of any one of claims 1 to 12, wherein the surface treatment comprises depositing a material, such as depositing an ink, or removing a material, such as drilling a hole, or chemically modifying the surface, such as providing energy capable of cross-linking the surface.

14. The part comprises: Automotive cover parts such as the cover parts of the passenger compartment of a car, in particular the cover parts of the dashboard and the doors; - Parts made of natural or artificial leather, in particular leather products or furniture parts or parts used in the manufacture of the visible parts of leather products or furniture parts, - parts having a textured surface, - metal or plastic parts being manufactured in contact with the surfaces of the mould, 14. The method according to any one of claims 1 to 13, wherein the compound is selected from the group formed by

15. 15. The method according to any one of claims 1 to 14, for decorating parts having regular or irregular surface relief, said surface relief being capable of corresponding in particular to grains, seams, seals, edges, engravings.

16. A robot including at least one gripping arm equipped with a laser shape measuring device and capable of acquiring three-dimensional shape measurement data, and at least one surface treatment tool; a computer in communication with the robot, the laser profilometer, and the at least one surface treatment tool and configured to control operation of the robot, the laser profilometer, and the at least one surface treatment tool; An apparatus comprising: An apparatus configured and capable of carrying out a method for selectively and locally treating a surface of a component according to any one of claims 1 to 15.

17. 17. The apparatus of claim 16, wherein the computer is configured to perform the digital data processing of steps (c) and (d).

18. 18. Apparatus according to claim 16 or 17, characterized in that the surface treatment tool is an inkjet printhead or a laser type light emitter.

19. A computer program comprising program code instructions for carrying out the steps of the method according to any one of claims 1 to 14, running on a computer intended and capable of controlling the activity of an apparatus according to any one of claims 16 to 18.

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