Method and equipment for applying a coating product to a surface

Abstract

To provide a method and installation for applying a coating product to a surface.SOLUTION: A method for applying a bead of a coating product to a surface by a print head 10 equipped with multiple nozzles 12A, 12B, where the coating is performed by moving the print head along a fixed trajectory T relative to the surface about an axis A10 parallel to central axes A12 of the nozzles. The method includes selecting certain nozzles 12A on the basis of a previous point P' of the trajectory and a direction F1' of the trajectory at the previous point, and activating the nozzles at a point P. The nozzles 12A are arranged in a line L12, or form a part of a nozzle group delimited by the line L12, where a regression line D12 of the line coincides with a line D perpendicular to the direction of the trajectory T or is as close as possible to the line perpendicular to the direction of the trajectory among lines defined with the nozzles.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for applying a bead of a coating product to a surface to be coated. The present invention also relates to equipment for applying such a bead to such a surface. [Background technology]

[0002] In the context of the present invention, a coating product is a product intended to be applied to a surface by forming a layer on the surface. The coating product may be an adhesive or putty, a paint, an ink or a varnish, in particular having a relatively high viscosity.

[0003] In the context of the present invention, a bead refers to a layer applied to a surface having a width strictly smaller than its length and a thickness strictly smaller than its width. For example, the thickness of a bead may be a few millimeters, while its width may be between 5 and 100 millimeters and its length may be greater than 1 meter.

[0004] To enable application to three-dimensional surfaces, the application head is sometimes attached to the wrist of a multi-axis robot. For other applications, the application head is fixed, and the object defining the surface to be coated is moved in front of the head by the multi-axis robot. Often, the bead is generated by extruding or ejecting the coating product through a calibrated slot to create a flat pattern. The relative movement between the application head and the object defining the surface to be coated must be perpendicular to the direction of the slot. Generally, the width of the bead is fixed and depends on the supply pressure of the coating product and the shape of the slot. Changing the orientation of the application head relative to the surface to be coated can result in a change in the bead width. Changing the orientation of the application head relative to the surface to be coated, following the curves of the surface, or adjusting the bead width requires dedicating a specific robot axis for this function or adding an axis to the robot. This increases the complexity of the robot and, as a result, the cost of the equipment for applying the bead.

[0005] This problem has been addressed by using application heads with rotational movement, as considered in WO 2001 / 85352, which requires pneumatic and / or electrical means of driving the instrument, which are relatively complex.

[0006] On the other hand, forming a bead in the form of a rectangular frame by moving the print head in translation without rotation is known from Korean Patent Publication No. 101355906, but it is not fully satisfactory at corners when two nozzles are provided, and causes excessive consumption of coating product when four nozzles are provided in a diamond shape. Furthermore, this tool does not allow for easy application of beads of complex shape, especially on irregular surfaces.

[0007] According to another approach, it is known from US Patent Application Publication No. 2020 / 086562 to arrange the nozzles on the print head so that at least one of the nozzles is not aligned with another nozzle during application, which reduces gaps in the product layer but causes excessive consumption of coating product in the case of bead application.

[0008] On the other hand, EP 1 884 365 A1 teaches applying the coating product by means of a print head that does not need to be rotated according to the shape of the part to be coated, and this approach is not easily adaptable to real part shapes. Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention aims to remedy these drawbacks by proposing a novel method for applying a bead of coating product to the surface to be coated, which makes it possible to apply a bead of uniform or quasi-uniform thickness with a well-defined shape, even if this bead has a complex and / or distorted shape. [Means for solving the problem]

[0010] To this end, the present invention relates to a method for applying a bead of coating product to a surface to be coated by means of a printhead with multiple nozzles, each nozzle being centered on a central axis, and the application of the coating product being carried out by moving the printhead and the surface to be coated relative to each other by moving the printhead relative to each other along a trajectory fixed relative to the surface, without rotating the printhead about an axis parallel to the central axis of the nozzle. The method comprises the steps of selecting a specific nozzle for a point on the trajectory based on the direction of the trajectory at this point and / or based on a previous point on the trajectory already reached by the printhead and the direction of the trajectory at this previous point, and activating the selected nozzle at this point. According to the present invention, the selected nozzles are arranged on a line or form part of a group of nozzles bounded by a line whose regression line coincides with a line perpendicular to the direction of the trajectory or that can be defined for the nozzles of the printhead as close as possible to a line perpendicular to the direction of the trajectory.

[0011] According to the present invention, the selection of nozzles of a particular printhead, whose linear regression line coincides with a line perpendicular to the direction of the trajectory or is defined as close as possible to a line perpendicular to the direction of the trajectory, makes it possible to adapt the number and arrangement of activated print nozzles based on the direction of the trajectory being followed, thus applying the coating product only from the nozzles that are best positioned for this purpose. The selection and activation of nozzles can be varied along the trajectory to dynamically adapt the application of the product based on the trajectory. The amount of coating product applied is therefore optimized according to the shape of the bead to be deposited on the surface being coated.

[0012] According to advantageous but not essential aspects of the invention, this method may be employed in any technically acceptable combination to incorporate one or more of the following properties: The nozzles of the printhead are arranged in rows or columns, while during the selection process, some of the nozzles in a particular row and / or some of the nozzles in a particular column are selected for activation together. The nozzles of the printhead are arranged in at least one arc of a circle, while during the selection process, nozzles in a portion of the arc of the circle are selected for activation together. The width of the area coated by a selected and activated nozzle is adapted according to the distance between this area and a nearby area coated by another nozzle. The width of the coated area is adapted by varying the operating frequency of the feeders of the selected and activated nozzles. The width of the area coated by a selected, normally activated nozzle is locally reduced to zero so as not to interfere with one or more areas of nearby coated product. The width of the printhead measured perpendicular to the direction of advancement is equal to or greater than the width of the applied bead measured perpendicular to the direction of advancement, while of the nozzles selected during the selection step, only those nozzles positioned opposite the path of the bead on the surface to be coated are activated. Information about the relative direction and speed of the print head with respect to the surface to be coated is provided to an electronic control unit by a robotic control unit which enables relative movement of the print head and the surface to be coated. Information about the relative direction and speed of the print head with respect to the surface to be coated is provided to an electronic control unit by an accelerometer or inertial unit mounted on the robot that allows relative movement of the print head and the surface to be coated.

[0013] According to another aspect, the present invention relates to an apparatus for applying a bead of coating product to a surface to be coated, the apparatus comprising: a print head with a plurality of nozzles, each centered on a central axis; a robot enabling relative movement of the print head and the surface along a trajectory fixed relative to the surface without rotation about an axis parallel to the central axis of the nozzles; and a control unit for each nozzle. According to the present invention, the control unit is configured to select and activate a nozzle of a particular print head at a point on the trajectory based at least on the direction of the trajectory at that point and / or on previous points on the trajectory already reached by the print head and the direction of the trajectory at those previous points.

[0014] This facility makes it possible to carry out the method of the present invention and achieves the same advantages as the method of the present invention.

[0015] Advantageously, the nozzles of the printhead are arranged in at least one arc of a circle, and preferably the body of the printhead has a circular cross section.

[0016] The invention will be better understood, and other advantages of the invention will become more apparent, in light of the following description of six embodiments of methods and apparatus according to the principles of the invention, given by way of example only and made with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic diagram of the principle of an installation according to the invention, seen from the front, configured to carry out the method according to the invention; [Figure 2] 2 is a schematic diagram of the principle of a portion of a mastic bead applied by the installation of FIG. 1 and according to a first application method according to the invention; [Figure 3] 3 is a view similar to FIG. 2 of an installation and application method according to a second embodiment of the invention; [Figure 4] 3 is a view similar to FIG. 2 of an application installation and method according to a third embodiment of the invention; [Figure 5] 1 is a schematic view of an application installation showing the bead to be produced and the application head before the execution of a fourth method according to the invention; [Figure 6] 6 is a diagram of the path of the nozzle relative to the bead in the installation of FIG. 5 during the execution of a fourth method according to the invention; [Figure 7] FIG. 10 is a schematic diagram of a fifth application method carried out to create beads in a fifth installation according to the invention. [Figure 8] 8 is a view similar to FIG. 7 corresponding to an installation for a sixth method according to the invention; DETAILED DESCRIPTION OF THE INVENTION

[0018] The installation I shown in Figures 1 and 2 is provided for applying a bead of adhesive C to an object O, which in this example is the body of a car. More precisely, in this example, the installation I makes it possible to create a bead of adhesive C for fixing a windshield to a surface S of the body of a car.

[0019] In one variation, the object to be coated may be, by way of non-limiting example, a part of an automobile body, such as a door or bumper, or more generally, any object that can be coated, such as a part of an aircraft body or a body of a household appliance.

[0020] In one variation, the applied product may be paint, in which case the bead C may be a strip of contrasting color on the body of the automobile.

[0021] The installation I comprises a conveyor 2 arranged to move an object O along a conveying axis X2 perpendicular to the plane of the drawing in FIG.

[0022] The installation I further comprises an application head 10 mounted at the end of an arm 22 of a multi-axis robot 20 arranged near the conveyor 2 .

[0023] The installation I further comprises an electric control unit 24 capable of controlling the robot 20 and an electric control unit 30 capable of controlling the application head 10 carried by the robot 20 .

[0024] The application head 10 comprises a number of nozzles 12 which are identical to one another and mounted on one face of the rigid parallelepiped body 14 of the printhead. By way of example, the nozzles may be of the type described in German patent application no. 102009029946. Other nozzle types are also conceivable, depending on the nature, in particular the viscosity, of the coating product to be applied.

[0025] The central axis of the printhead 10, designated A10, passes through the center of the surface 14 of the body into which the nozzles 12 open and is oriented toward the surface S to be coated when the printhead is actuated to apply the coating product. The central axis of the nozzles 12, designated A12, is located at the center of the jet of coating product emitted from that nozzle. Each nozzle 12 is centered about its central axis A12. Axis A12 is parallel to axis A10.

[0026] In particular, the electrical control unit 30 is configured to control the operation of the individual nozzles 12. The electrical nozzle control unit 30 does not have to be located in the robot 20.

[0027] Information about the relative direction and relative speed of the print head 10 with respect to the surface S to be coated is provided to an electronic control unit 30 by the control unit 24 of the robot 20 .

[0028] In some variations, the control units 24 and 30 may be identical.

[0029] As can be seen in more detail from Figure 2, where the surface S to be coated is flat and parallel to the plane of Figure 2, when it is necessary to create a bead C of coating product on a surface S, for example the surface of an automobile body O in the example of Figures 1 and 2, the print head 10 is moved along a trajectory T. This trajectory T is parallel to the surface S in this example, and therefore flat, and is oriented in Figure 2 in the direction of arrow F1, which arrow F1 represents the direction of the trajectory at different points P. The trajectory T is spaced from the surface S to be coated by a distance that constitutes the distance for applying the coating product.

[0030] In practice, this trajectory T may be curved, extending substantially toward the center of the bead C being produced. For example, in FIG. 2, trajectory T includes a curve that corresponds to the curved region of bead C. trajectory T is the curve along which the print head travels to apply bead C. As shown in FIG. 2, this curve may be flat or distorted, i.e., three-dimensional.

[0031] In this Figure 2, the print head 10 is shown in the direction of arrow F1, which the print head 10 follows in four positions along the trajectory T: a first position opposite the straight section of code C in the lower left corner of Figure 2, a second position at the entrance to the curve, a third position at the exit of the curve, and a fourth position opposite the straight section of code C defined after the curve.

[0032] As shown in Figure 2, there are 25 nozzles 12 in the body, arranged along their respective axes A12 perpendicular to the plane of the figure, in an array of 5 rows and 5 columns of 5 nozzles each on a rectangular surface. In Figure 1, the nozzles are shown protruding from the body 14. However, the nozzles may be entirely incorporated into the body and may be flush with the rectangular surface.

[0033] To simplify and optimize the axes of the robot 20, the movement of the body 14 of the print head 10 along the trajectory T is performed by a combination of linear and circular translations, i.e., translation of the body 14 along the curved trajectory T, without rotation of the body 14 about a central axis A10 of the body 14 that passes through the geometric center 142 of the body 14, or about an axis parallel to axis A10 and passing through another point on the body 14.

[0034] 2, black nozzles 12 represent nozzles that are active during movement of body 14 along trajectory T, while white nozzles represent nozzles that are inactive. "Active" means that the nozzle is ejecting coating product as printhead 10 moves. "Inactive" means that the nozzle is not ejecting coating product during this movement.

[0035] To ensure proper application of the coating product intended to form the bead C, the nozzle 12 is selected based on a position of the print head 10 along the trajectory T, i.e., a point P of the trajectory at which a given point of the print head is located, for example, its geometric center. In practice, the determination of the position of the print head 10 along the trajectory T is made by determining the position of the center 142, or other point of interest of the body 14, along that trajectory.

[0036] The trajectory T is supposed to be known to the electronic control unit 30 at any point P, in particular with respect to the direction of the trajectory T, which is defined as the tangent to the trajectory at that point and represented by the arrow F1. At the trajectory point P, the unit 30 can determine a straight line D perpendicular to the direction of the trajectory, as shown for the positions of the four printheads visible in Figure 2.

[0037] In a variant, the trajectory T does not have to be known in advance by the electronic unit 30, but may be known by the electronic control unit 24 of the robot 20. In the case of a print head 10 attached to the robot 20, the direction and speed of its movement can be determined by attaching an accelerometer or a central inertial unit to the print head. This accelerometer or this central inertial unit makes it possible to know, in real time, the movement of the print head and thus to locally reconstruct the trajectory T followed by the print head. In this case, it is also possible to determine a line D perpendicular to the direction of the trajectory T at each point P of the trajectory.

[0038] In all cases, an axis Z is defined at point P on the path, directed from the center of the print head toward the surface S to be coated. This axis Z is perpendicular to the plane of Figure 2. The movement of the body 14 of the print head 10 along the trajectory T is said to be translational, which corresponds to the fact that this movement is performed without rotation about axis Z.

[0039] Unit 30 selects from among the nozzles 12 a group of nozzles whose path relative to bead C is as close as possible to line D. Nozzles in this group of nozzles are designated 12A, and other nozzles in the printhead are designated 12B. In practice, nozzle 12A is positioned so that the regression line for the position of nozzle 12A is as close as possible to line D. Here, nozzle 12A is positioned in alignment with line L12.

[0040] In the example of FIG. 2, in a first printhead position, the selected group of nozzles 12A corresponds to a row of the nozzle array 12 formed in the body 14. Therefore, line L12 is the average line of this row and is a straight line. In a second position, the selected group of nozzles 12A corresponds to a diagonal of the nozzle array 12. Therefore, line L12 is the average line of this diagonal and is also a straight line. In a third position, the selected group of nozzles 12A describes a broken line L12 on the surface of the body 14, and this broken line L12 has a regression line D12 that is closest to line D perpendicular to trajectory T among the lines that can be described in the nozzle array 12. In a fourth position, the selected group of nozzles 12A corresponds to a column of the nozzle array 12. Therefore, line L12 is the average line of this column and is also a straight line. 2, the line L12 is coincident with the regression line D12 and with the straight line D. In the third position, the line L12 is approximated by a regression line D12 that is parallel to the line D but does not coincide with the line D.

[0041] In the two linear portions of the bead C corresponding to the first and fourth positions shown in Figure 2, two selected groups of nozzles 12A are formed by two perpendicular lines of nozzles, i.e., rows of nozzles 12 in the first configuration and columns of nozzles 12 in the second configuration.

[0042] In this embodiment, all selected nozzles 12A are activated to apply the coating product at point P. Thus, nozzles 12A are black in FIG.

[0043] Therefore, the method of selecting a particular nozzle, i.e., nozzle 12A at point P, based on the direction F1 of the trajectory T at point P, after the step of activating these nozzles, allows the coating product to be applied efficiently and economically with the nozzles used, sufficient to avoid "gaps" or uncoated areas in the bead C, but without using too much coating product or making the bead too thick.

[0044] According to one embodiment, shown only for the second position of printhead 10 in Figure 2, the nozzle 12A is determined by taking into account a point P' on the trajectory previously reached by printhead 10 and the direction F1' of the trajectory at this previous point P'. This approach makes it possible to know which nozzle 12A was activated at the previous point P' and which nozzle 12A should be activated at point P. This variant is applicable to other printhead positions along the trajectory T, and to other embodiments described below.

[0045] The variant using the previous point P' and direction F1' can be performed instead of or in addition to the basic approach using only the direction F1 at point P.

[0046] Selection of nozzle 12A among array 12 of nozzles can be done as soon as trajectory T is known, prior to creating bead C. In other words, the process of selecting nozzle 12A can be done prior to using robot 20 and application head 10.

[0047] In this case, it is then also possible to take the surface area S into account when selecting the nozzle 12A. This results in a modification of the linear regression algorithm that calculates the straight line D12 from the line L12, taking into account the effect of the nozzle on the surface S.

[0048] Furthermore, it is then possible to provide beads with right angles created by rectangular arrays, without overlap at the interior angles due to, for example, 90 degree changes of direction.

[0049] In one variant, the selection and activation steps follow each other in real time. In particular, the selection of the activated nozzle 12A can be performed at each travel step of the arm 22 of the robot 20 based on the trajectory T stored in the electronic control unit 30. Real-time velocity information relative to the robot tool center according to the axes of the Cartesian reference system relative to the part being coated is available. By integrating these velocity values, changes in the position of the print head relative to the part can be estimated. This approach makes it possible to take into account the actual print head position during application of the bead C and to allow for possible adjustments of the trajectory T based on this actual position.

[0050] The application programmer can choose how to determine which nozzles in the nozzle array 12 should constitute the activated nozzles 12A, depending on how the line of nozzles approximates a straight line D perpendicular to the trajectory T. To do this, a regression method (linear or non-linear, polynomial, etc.) including an error calculation (quadratic or not, least squares, etc.) can be used.

[0051] In the second to fifth embodiments of the present invention shown in FIG. 3 onwards, elements similar to those in the first embodiment have the same reference numerals.

[0052] The surface S to be coated is again assumed to be flat and parallel to the plane of Figure 3 et seq., and movement of the print head along its trajectory T, defined in the first embodiment, which is also flat, is performed by a combination of translations parallel to this surface S, without rotations about the central axis A10 of the print head as defined in the first embodiment, an axis parallel to the central axis A10, or about axis Z, defined in the first embodiment.

[0053] In the following, we will mainly explain what distinguishes these embodiments from the embodiments of Figures 1 and 2, and will make clear that the methods described with reference to Figures 3 onwards can be carried out with the installation I of Figure 1, especially if the latter is applied to the printhead structure 10.

[0054] In the embodiment shown in Figure 3, the body 14 of the printhead 10 is cylindrical and circular in cross section, with twelve nozzles 12 distributed over a disk-shaped surface. No nozzles are located at the geometric center 142 of the body 14 of the printhead 10. Figure 3 shows five positions of the application head 10, for which straight lines D perpendicular to the direction F1 of the trajectory T are marked at points P of the trajectory, corresponding to these five positions.

[0055] The nozzles 12 are distributed in a circle centered on the geometric center 142 of the body 14, which is considered to be aligned with point P of the trajectory T. In this example, the selected nozzles 12A are those nozzles located ahead of line D, relative to line D, in the direction of travel of the printhead 10 along the trajectory T. Thus, in this example, a line L12 passing through the selected nozzles 12A closest to other non-selected nozzles 12B is a diameter of the body 14 of the printhead 10, and this diameter overlaps line D at each point P of the trajectory. The selected nozzles 12A also include those nozzles located on line L12.

[0056] Line L12 defines the pairing of nozzle 12A with respect to nozzle 12B. Because line L12 is the diameter of body 14, line L12 coincides with its regression line D12.

[0057] The unselected nozzles 12B are behind line L12 and line D in the direction of printhead travel along trajectory T.

[0058] In this embodiment, the selected and activated nozzles 12A are distributed in an arc of a circle C12 located in front of the body 14 being moved along the trajectory T relative to the line L12, which allows for uniform application of the coating product across the width of the bead T without excessive thickness that would occur if all the printhead nozzles 10 were activated along the entire trajectory.

[0059] As the movement of the body 14 of the print head 10 along the trajectory T is effected by linear or circular translation, the nozzles 12A selected and activated for application of a coating product intended to form a bead C vary among the five configurations shown in FIG. 3.

[0060] In the embodiment shown in FIG. 4, the body 14 of the printhead 10 is again cylindrical and circular in cross section, and, as in the first embodiment, is centered about a geometric center 142 corresponding to the nozzle 12.

[0061] In this embodiment, the nozzles 12 are distributed over the entire surface of the body 14 and are not arranged in a single circle. In fact, the nozzles are distributed over the disk-shaped surface in multiple concentric circles centered on a center 142.

[0062] Again in this example, based on movement of the printhead 10 in linear and circular translation along the trajectory T, different groups of nozzles 12A are selected based on the direction F1 of the trajectory T. The groups of nozzles 12A are defined relative to other nozzles 12B by a line L12 that takes into account a line D perpendicular to the direction of the trajectory T at each point P of this trajectory T.

[0063] In this example, the group of selected nozzles 12A roughly corresponds to a half disk, with the selected nozzles 12A arranged on an arc of a circle. In the first and fourth positions, where the printhead moves in a straight line, line L12 is straight and extends along the diameter of the body 14, overlapping line D at point P of the considered trajectory. In the second and third positions, corresponding to the beginning and exit of the bend, respectively, the selected nozzles 12A located at the boundary with the unselected nozzles 12B extend along line L12, which is curved (i.e., not straight) but close to line D perpendicular to trajectory T. In this example, line L12 in the second and third positions is a broken line formed by a series of straight line segments, as in the third position in FIG. 2 . Here, line L12 is selected from among the lines that can be defined by the nozzles 12 on the body 14, as the line whose regression line D12 is as close as possible to line D. As in the first embodiment, the programmer can select the approximation method.

[0064] In this embodiment, the printhead has 21 nozzles.

[0065] 5 and 6 show the production of bead C by a printhead 10 whose body 14 is cylindrical and circular in cross section and has eight nozzles 12 distributed around the outer edge of its disk-shaped surface. As in the previous embodiment, the geometric center of body 14 is designated 142, and this geometric center is moved along a predetermined trajectory T whose direction of advance is marked by arrow F1.

[0066] The shape of the track T is such that the cord C has a complex shape having a first relatively gentle bend and a second relatively sharp bend.

[0067] As can be seen in FIG. 6 (where the solid lines represent the path of the selected nozzle and the dashed lines represent the path of the unselected nozzle 12B), the nozzle can be selected based on the direction of travel of the body 14 along the trajectory T.

[0068] The eight nozzles 12 are marked with distinct reference numerals 121 through 128. In FIG. 6, the trajectories T12i of nozzles 12i are marked (i=1 through 8). For each trajectory T12i, the path of nozzle 12i is represented by dashed lines when nozzle 12i is not selected, i.e., type 12B, in the sense of the preceding description, and by solid lines when nozzle 12i is selected, i.e., type 12A, in the sense of the preceding description. For example, trajectory T121 indicates that nozzle 121 is selected only from the beginning of the final straight section of trajectory T after the second bend. In contrast, trajectory T122 indicates that nozzle 122 is selected at the beginning of trajectory T, up to the beginning of the first bend, and then in the final straight section after the second bend. Trajectory T123 of nozzle 123 indicates that nozzle 123 is selected in the first straight section of trajectory T for the main part of the first bend and then deselected. Trajectory T124 for nozzle 124 indicates that nozzle 124 is selected at the beginning and until halfway through the portion of trajectory T between the first and second bends, and then deselected. Trajectory T125 for nozzle 125 indicates that nozzle 125 is selected until the beginning of the second bend. Trajectory T126 for nozzle 126 indicates that nozzle 126 is selected from the beginning of the first bend to the exit from the second bend. Trajectory T127 for nozzle 127 indicates that nozzle 127 is selected from the exit of the first bend to the end of the move. Trajectory T128 for the eighth nozzle indicates that the eighth nozzle is selected from the end of the first bend to the end of the move.

[0069] In this case, in a manner corresponding to that envisaged for the second embodiment, but with a more complex implementation and a different number of nozzles due to the relatively complex shape of bead C, nozzles 12i constituting the nozzles 12A selected to be activated at point P of trajectory T are understood to be nozzles located towards the front of the movement of printhead 10. Thus, in this example, at the beginning of the trajectory, the selected nozzles 12A are nozzles 122-125. At the beginning of the first bend, the selected nozzles 12A are nozzles 122-126. Between the first and second bends, the selected nozzles 12A are nozzles 125, 126, and 127. At the exit of the second bend, the selected nozzles 12A are nozzles 121, 122, 127, and 128.

[0070] The width of the applied bead C is L C is denoted as L10, measured perpendicular to the direction F1 of the trajectory T, and this width is assumed to be constant. The useful printhead width, i.e., the width of the attachment of the nozzle 12j to the body 14, is denoted as L10, also measured perpendicular to the direction of the trajectory T, where width L10 is equal to the diameter of the body.

[0071] 6 shows that a particular nozzle 12i can be selected at point P of the trajectory T when it is not facing the path of the bead C being produced, since the trajectory T12i of that nozzle 12i is in a continuous line. This is the case, for example, for nozzles 122 and 125 in the first part of the trajectory, before the first bend. This is because width L10 is strictly greater than width LC.

[0072] In this case, it is not necessarily required that all selected nozzles 12A be activated. A further control step can be provided to verify that a given nozzle 12i that is part of the selected nozzles 12A is actually facing the path of the bead C on the surface S to be coated, i.e., on the area S of the surface to be coated that is intended to be coated by the bead C. In this case, the activation of the nozzle 12i in question is verified and the nozzle is activated; otherwise, its activation is stopped.

[0073] 6, nozzles 126, 127 and 128 are selected between two bends but are not activated, because the coating product that would come out of these nozzles would fall outside the path of the bead C on the surface S to be coated. The same applies to nozzles 122, 126 and 127 after the second bend.

[0074] Thus, because the actuation of the selected nozzle 12A takes into account the width LC of the bead C at each point P of the trajectory, the present invention allows the same printhead 10 to be used to apply beads C of different widths LC, which are less than or equal to the useful printhead width L10.

[0075] Width L C If varies along the bead C, the checks considered above apply.

[0076] 7 and 8, the body 14 of the printhead 10 has 16 nozzles 12j (j is 1 to 16) distributed around the outer edge of the disk-shaped surface of the body 14. In FIGS. 7 and 8, the area of ​​the bead C applied by a nozzle 12j is marked by the symbol Z12j (j is 1 to 16).

[0077] Figure 7 shows that a bead C having the same shape as that shown in Figures 5 and 6 is produced by a succession of bead portions constituted by regions Z12j, which is possible thanks to the selection of a particular nozzle 12j at each point of the trajectory T, which constitutes a selected nozzle in the sense of the selected nozzle 12A of the first embodiment and is activated at that point.

[0078] It can be seen that not all nozzles are used to form bead C. In this Figure 7, there is in fact no area corresponding to nozzle 121 or nozzle 123.

[0079] In this Figure 7, it can be seen that relatively large gaps exist on the outside of the first bend between regions Z125 and Z126 on the one hand, and between regions Z126 and Z127 on the other hand, while regions Z1213, Z1214, Z1215 and Z1216 overlap on the inside of the second bend.

[0080] In the case of a sealant bead, the objective is to have a completely coated surface. In the case of an adhesive or acoustic bead, a suitable volume is required.

[0081] This problem is addressed in the implementation of the method shown in Figure 8, in which the width L126 of region Z126 is locally increased at the end of this region, in the direction of movement of the print head along trajectory T, in order to avoid a "gap" in bead C. To this end, the actuation of nozzle 126 can be modified in the corresponding region outside the first bend, for example by increasing its actuation frequency and / or the opening time of its discharge valve.

[0082] Similarly, the initiation of nozzles 1213, 1214 and 1216 is delayed at the exit from the second bend to apply only the coating product coming from nozzle 1215 in this portion of bead C, avoiding the overlap seen in Figure 7, which may result in a too thick bead C. Therefore, in this portion of bead C, the widths L1213, L1215 and L1216 of the respective zones Z1213, Z1215 or Z1216 are temporarily set to zero, for example by reducing their operating frequency and / or the duration of opening of their discharge valves to zero, to constitute the distance between these zones and the nearby zone Z1214.

[0083] Similarly, the end of region Z12j, i.e. its width reduced to 0, can be addressed so as not to interfere with one or more nearby regions, for example by reducing its operating frequency and / or the duration of the opening of its discharge valve to 0.

[0084] According to one embodiment of the invention not shown, the transition from zero width to the nominal width of the region Z12j may be gradual, for example by gradually changing the operating frequency and the duration of the discharge of each nozzle.

[0085] In the examples discussed above, the width of the coating area of ​​the selected nozzles is adapted by adjusting the discharge amount of coating product coming out of each nozzle, which is controlled by the operating frequency and / or the duration of the opening of the associated discharge valve.

[0086] The operating frequency of the nozzle can be controlled by a piezoelectric component or other equivalent means, for example a solenoid valve.

[0087] 7 and 8, by deactivating certain selected nozzles when they are not facing the path of bead C on the surface S to be coated, it is further taken into account that the useful width L10 of printhead 10 is greater than the width LC of bead C. This is particularly the case for nozzles 121 and 128 located at the side edges of the printhead in the portion of trajectory T before the first bend.

[0088] Regardless of the embodiment, selecting the nozzles 12A to be activated along the trajectory T based on the direction of the trajectory makes it possible to adapt the application of the coating product to the shape of the bead C to be created, while maintaining a relatively simple mode of movement of the application head 10 through the use of linear or circular translation, without rotating the print head about the central axis of the print head or about an axis parallel to the central axis of the print head, for example about the Z axis.

[0089] In the embodiment discussed above, the selection of the nozzles 12A and their activation is performed automatically in an electric nozzle control unit 12, which is either integrated into the robot 20, for example unit 30 of installation I in FIG. 1, or is external to the robot.

[0090] In the case where the surface S to be coated is curved, i.e., not flat, the trajectory T can be adapted and need not be flat. Additionally, the printhead can rotate during movement about and between two transverse axes B10 and C10 defined by the body 14 and perpendicular to axis A10. Even in this case, the printhead 10 does not rotate about its central axis A10, even though the movement of the printhead in the reference frame of the surface is not a simple combination of translations. This allows the surface of the printhead 14, on which the nozzle 12 is typically mounted, to remain parallel to the surface S to be coated in order to deposit a bead C in a curved area, such as the windshield mounting area seen in FIG. 1 .

[0091] According to one variant of the invention not shown, the print head 10 is fixed and the surface S to be coated is moved by the robot in linear or circular translational movements opposite the nozzle 12. In this case, in the reference system of the surface S, the print head 10 and the nozzle 12 move along a trajectory T. Again, if the electronic unit 30 does not know the trajectory T in advance, the robot supporting the part to be coated may be equipped with an accelerometer or central inertial unit making it possible to locally reconstruct, in real time, the trajectory T followed by the print head 10 in the reference system of the surface S to be coated. Again, when the print head is fixed, the robot is programmed to keep the mean plane of the surface to be coated as parallel as possible to the plane of the nozzle defined by the surface of the body 14 on which the nozzle is mounted.

[0092] Regardless of whether it is the surface or the print head that is fixed during application, the robot used to ensure the relative movement between the print head and the surface to be coated may be of any known type, such as the multi-axis one shown in FIG. 1, a horizontal articulated robot (Scara) or a reciprocator type.

[0093] According to another variant of the invention, not shown, the nozzles 12 or some of them are arranged in the arc of a circle, while the body 14 is not circular in cross section.

[0094] The present invention is shown in the figures where the printhead has 8, 12, 16, 21 or 25 nozzles. The present invention is applicable to other numbers of nozzles in any distribution pattern on the body 14. However, as will be apparent from the presentation of the second through sixth embodiments, a distribution of the nozzles in one or more circular arcs is particularly advantageous.

[0095] Although the invention is presented in the context of nozzles 12 being distributed in rows and columns or in the arc of a circle, other distributions are envisaged, provided that the nozzles selected are in a row or are part of a group bounded by a line whose linear regression line is defined as described above.

[0096] The above-discussed embodiments and variations can be combined with one another in the scope of the appended claims to create new embodiments of the present invention. The following embodiments can be given as examples of the present invention. (Appendix 1) A method for applying a bead of coating product (C) to a surface to be coated (S) by means of a printhead (10) comprising a plurality of nozzles (12), each nozzle being centered on a central axis (A12), and the application of the coating product being effected by moving the printhead and the surface to be coated relative to one another by relative printhead movement along a trajectory (T) fixed relative to the surface to be coated, without rotating the printhead about an axis (A10) parallel to the central axis (A12) of the nozzle, the method comprising: positioning a particular nozzle (12A) relative to a point (P) of the trajectory (T) at the trajectory at this point; a selection step of selecting a nozzle (12A) based on the direction (F1) of the trajectory (T) and / or based on a previous point (P') of the trajectory already reached by the print head and the direction (F1') of the trajectory at this previous point, and an activation step of activating the selected nozzle (12A) at this point (P), characterized in that the selected nozzle (12A) is located on a line (L12) or is part of a group of nozzles bounded by the line (L12), and the regression line (D12) of the line (L12) coincides with a line (D) perpendicular to the direction of the trajectory (T) or is as close as possible to a line perpendicular to the direction of the trajectory among the lines that can be defined by the nozzles (12) of the print head (10). (Appendix 2) 2. The method of claim 1, wherein the nozzles (12) of the print head (10) are arranged in rows and columns, and during the selection step, some of the nozzles (12A) in a particular row and / or some of the nozzles (12A) in a particular column are selected for activation together. (Appendix 3) 2. The method of claim 1, wherein the nozzles (12) of the print head (10) are arranged in at least one arc of a circle, and during the selection step, nozzles (12A) of a portion of the arc of the circle are selected for operation together. (Appendix 4) 4. The method according to any one of claims 1 to 3, characterized in that the width (L126, L1213, L1215, L1216) of the area (Z126, Z1213, Z1215, Z1216) of the coating emerging from the selected and activated nozzle (126, 1213, 1215, 1216) is adapted based on the distance between this area and a nearby area (Z125, Z127, Z1214) from another nozzle (125, 127, 1214). (Appendix 5) 5. The method according to claim 4, characterized in that the width (L126) of the coating zone (Z126) is adapted by varying the operating frequency of the feeder of the selected and activated nozzle (126). (Appendix 6) A method as described in Appendix 4 or 5, characterized in that the width (L1213, L1215, L1216) of the coating area by a selected and normally activated nozzle (1213, 1215, 1216) is locally reduced to 0 so as not to interfere with one or more nearby coating product areas (Z1214). (Appendix 7) The width of the print head (L10), measured perpendicular to the direction of the trajectory (F1), is compared to the width of the applied bead (C), measured perpendicular to the direction of the trajectory (L C ) or more, and among the nozzles (12A) selected during the selection step, only the nozzles (12A) positioned opposite the path of the bead on the surface (S) to be coated are activated. (Appendix 8) 8. The method according to any one of claims 1 to 7, characterized in that information about the relative direction and speed of the print head (10) with respect to the surface (S) to be coated is provided to the electronic control unit (30) by a control unit (24) of a robot (20) enabling the relative movement of the print head and the surface to be coated. (Appendix 9) 8. The method according to any one of claims 1 to 7, characterized in that information about the relative direction and speed of the print head (10) with respect to the surface (S) to be coated is provided to the electronic control unit (30) by an accelerometer or inertial unit integrated into a robot enabling the relative movement of the print head and the surface to be coated. (Appendix 10) An installation (I) for applying a bead of coating product (C) to a surface (S) to be coated, comprising: a printhead (10) having a plurality of nozzles (12) each centered on a central axis (A12); a robot (20) that allows relative movement of the print head and the surface to be coated along a trajectory (T) fixed relative to the surface to be coated, without rotation about an axis (A10) parallel to the central axis (A12) of the nozzle; A control unit (30) for each nozzle wherein the control unit (30) is configured to select and activate a particular nozzle (12A) of the print head at a point (P) of the trajectory (T) based at least on the direction (F1) of the trajectory at this point and / or based on a previous point (P') of the trajectory already reached by the print head and the direction (F1') of the trajectory at this previous point. (Appendix 11) 11. The apparatus of claim 10, wherein the nozzles (12) of the print head (10) are arranged in at least one arc of a circle. (Appendix 12) 12. The apparatus according to claim 11, wherein the body (14) of the print head has a circular cross section.

Claims

1. A method for applying a bead of coating product (C) to a surface to be coated (S) by means of a print head (10) comprising a plurality of nozzles (12), each nozzle being centered on a central axis (A12), and the application of the coating product being performed by moving the print head and the surface to be coated relative to each other by relative movement of the print head along a trajectory (T) fixed relative to the surface to be coated, without rotating the print head about an axis (A10) parallel to the central axis (A12) of the nozzle, the method comprising: a selection step of selecting a particular nozzle (12A) for a point (P) of the trajectory (T) based on the direction (F1) of the trajectory at this point and / or based on a previous point (P') on the trajectory already reached by the print head and the direction (F1') of the trajectory at this previous point; and an actuation step of actuating the nozzles selected in (P), wherein the selected nozzles (12A) are arranged on a line (L12) or are part of a group of nozzles bounded by the line (L12), and the regression line (D12) of the line (L12) coincides with a line (D) perpendicular to the direction of the trajectory (T), or can be aligned with a line perpendicular to the direction of the trajectory among the lines that can be defined by the nozzles (12) of the print head (10). and the width (L126, L1213, L1215, L1216) of the area (Z126, Z1213, Z1215, Z1216) for the coating coming out of the selected and activated nozzle (126, 1213, 1215, 1216) is adapted based on the distance between this area and a nearby area (Z125, Z127, Z1214) by another nozzle (125, 127, 1214).

2. 2. The method of claim 1, wherein the nozzles (12) of the printhead (10) are arranged in rows and columns, and during the selection step, some of the nozzles (12A) in a particular row and / or some of the nozzles in a particular column are selected for activation together.

3. 2. The method of claim 1, wherein the nozzles (12) of the printhead (10) are arranged in at least one arc of a circle, and during the selecting step, the nozzles (12A) of a portion of the arc of the circle are selected for operation together.

4. 4. A method according to claim 3, characterized in that the width (L126) of the coating zone (Z126) is adapted by varying the operating frequency of the feeder of the selected and activated nozzle (126).

5. 5. The method according to claim 1, wherein the width (L1213, L1215, L1216) of the coating area by a selected and normally activated nozzle (1213, 1215, 1216) is locally reduced to zero so as not to interfere with one or more nearby coating product areas (Z1214).

6. The width (L10) of the print head measured perpendicular to the direction of the trajectory (F1) is the width (L) of the applied bead (C) measured perpendicular to the direction of the trajectory. C 6. The method according to claim 1, wherein the number of nozzles (12A) selected during the selection step is equal to or greater than 100, and wherein only the nozzles (12A) positioned opposite the path of the bead on the surface (S) to be coated are activated.

7. 7. A method according to any one of claims 1 to 6, characterized in that information about the relative direction and speed of the print head (10) with respect to the surface (S) to be coated is provided to the electronic control unit (30) by a control unit (24) of a robot (20) enabling the relative movement of the print head and the surface to be coated.

8. 7. A method according to any one of claims 1 to 6, characterized in that information about the relative direction and speed of the print head (10) with respect to the surface (S) to be coated is provided to the electronic control unit (30) by an accelerometer or an inertial unit integrated in a robot enabling the relative movement of the print head and the surface to be coated.

9. 1. An installation (I) for applying a bead of coating product (C) to a surface (S) to be coated, comprising: a printhead (10) comprising a plurality of nozzles (12) each centered on a central axis (A12); a robot (20) that allows relative movement of the print head and the surface to be coated along a trajectory (T) fixed relative to the surface to be coated, without rotation about an axis (A10) parallel to the central axis (A12) of the nozzle; A control unit (30) for each nozzle 1. An installation comprising: a control unit (30) configured to select and activate a specific nozzle (12A) of the print head at a point (P) of the trajectory (T) based on at least the direction (F1) of the trajectory at this point and / or based on a previous point (P') of the trajectory already reached by the print head and the direction (F1') of the trajectory at this previous point, wherein the width (L126, L1213, L1215, L1216) of a region (Z126, Z1213, Z1215, Z1216) of the coating emerging from the selected and activated nozzle (126, 1213, 1215, 1216) is adapted based on the distance between this region and a nearby region (Z125, Z127, Z1214) of another nozzle (125, 127, 1214).

10. 10. The installation according to claim 9, characterized in that the nozzles (12) of the printhead (10) are arranged in at least one arc of a circle.

11. 11. The installation according to claim 10, characterized in that the body (14) of the printhead has a circular cross section.

Images