Method and apparatus for applying a coating product to a surface

Abstract

The invention relates to a method for applying a coating material stripe to a surface to be coated using a print head equipped with a plurality of nozzles, each nozzle being centered on a central axis, the coating material being applied by relative movement of the print head along a trajectory fixed relative to the surface to be coated, the print head and the surface to be coated being moved relative to each other without rotating the print head about an axis parallel to the central axis of the nozzles, the method comprising the steps of selecting a number of nozzles for a point on the trajectory based on the trajectory direction at that point and / or based on a previous point on the trajectory already reached by the print head and the trajectory direction at that previous point, and activating the selected nozzles at that point, the selected nozzles being arranged in a row or as part of a group of nozzles defined by a line whose line of return coincides with a line perpendicular to the trajectory direction or as close as possible to a line perpendicular to the trajectory direction in the line defined by the nozzles of the print head.

Description

Technical Field

[0001] The present invention relates to a method for applying a bead of a paint product to a surface to be coated. The present invention also relates to an apparatus for applying a bead of the paint product to such a surface.

[0002] According to the present invention, the coating product is a product for applying to a surface to form a coating thereon. The coating product can be a relatively high viscosity adhesive, especially putty, or a paint, ink or varnish.

[0003] According to the present invention, a coating strip is a coating applied to a surface, the width of which is substantially smaller than the length, and the thickness of which is substantially smaller than the width. For example, the coating strip may be a few millimeters thick, with a width between 5 and 100 millimeters and a length greater than 1 meter. Background Art

[0004] In order to be able to coat three-dimensional surfaces, an application head is sometimes mounted on 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 multi-axis robot. The coating strip is often formed by extruding or spraying the paint through a standardized slot to form a flat shape. The relative movement of the print head and the object defining the surface to be coated must be perpendicular to the direction of the slot. The width of the coating strip of the coating product is generally fixed and depends on the paint feed pressure and the slot geometry. The width of the coating strip of the coating product can be changed by changing the orientation of the print head relative to the surface to be coated. Changing the orientation of the print head relative to the surface to be coated or along a curved part of the surface, or adjusting the width of the coating strip of the coating product, requires a dedicated robot axis to perform this function, or an additional axis to the robot. This increases the complexity of the robot and therefore the cost of the equipment for applying the coating strip of the coating product.

[0005] This problem has been addressed by using a print head with a swirl motion, as described in detail in WO-A-2001 / 85352. The swirl motion requires relatively complex pneumatic and / or electric means of driving the material.

[0006] On the other hand, KR-A-101355906 proposes to form a rectangular frame of coating product by translating the print head without rotation. However, when two nozzles are provided, this is not entirely satisfactory, and when four nozzles are provided in a diamond shape, excessive consumption of coating product occurs. Furthermore, this device does not easily apply coating product strips with complex geometries, particularly on curved surfaces.

[0007] According to another approach, US-A-2020 / 086562 proposes arranging nozzles on a print head such that at least one nozzle is not aligned with another nozzle during coating. This prevents gaps in the coating, but can lead to excessive coating consumption in the case of bead coating of the coating product.

[0008] On the other hand, EP-A-1884365 proposes applying the coating with a print head that does not have to be rotated according to the geometry of the part to be coated. This method is not easy to adapt to the geometry of the actual part.

[0009] The present invention aims to remedy these drawbacks by proposing a new method for applying a coating product strip to a surface to be coated, whereby coating product strips of equal or nearly equal thickness with a well-defined geometry can be applied, even when the coating product strips have complex and / or curved shapes. Summary of the Invention

[0010] To this end, the present invention relates to a method for applying a coating strip of a coating product to a surface to be coated by means of a print head equipped with a plurality of nozzles, each nozzle being centered on a central axis, the coating product being applied by relative movement of the print head along a trajectory fixed relative to the surface to be coated, so that the print head and the surface to be coated move relative to each other without rotating the print head around an axis parallel to the central axis of the nozzles, the method comprising the steps of selecting a number of nozzles for a point on the trajectory based on the direction of the trajectory at that point and / or based on a previous point of the trajectory already reached by the print head and the direction of the trajectory at that previous point, and the method comprising the step of starting the selected nozzles at that point, characterized in that the selected nozzles are arranged in a row or as part of a group of nozzles defined by a line, whose regression line coincides with a line perpendicular to the direction of the trajectory, or is as close as possible to a line perpendicular to the direction of the trajectory in the line defined by the nozzles of the print head.

[0011] According to the present invention, the print head nozzles are selected by a line whose linear regression line coincides with a line perpendicular to the direction of the track, or whose linear regression line is as close as possible to the line perpendicular to the track. This allows the number and arrangement of the activated print nozzles to be adjusted according to the direction of the track to be followed, so that the coating product is applied only from the nozzles optimally arranged for this purpose. The selection and activation of the nozzles can be varied along the track, so that the application of the product is dynamically adjusted according to the track. As a result, the amount of coating product applied is optimized, and the geometry of the coating strip applied to the surface to be coated is also optimized.

[0012] According to an advantageous but non-limiting embodiment of the invention, this method may have one or more of the following features, in any technically permissible combination:

[0013] The nozzles of the print head are arranged in rows and columns; and, during the selecting step, nozzles of a portion of some rows and / or a portion of some columns are selected together for firing.

[0014] The nozzles of the print head are arranged on at least one circular arc; and, during the selecting step, the nozzles of a part of the circular arc are selected together for activation.

[0015] The width of the area coated from the selected and activated nozzle is adjusted according to the distance between this area and adjacent areas coated from other nozzles.

[0016] - The width of the coating area is adjusted by varying the dosing activation frequency of the selected and activated nozzles.

[0017] The width of the area coated from the selected and normally activated nozzles is locally reduced to zero in order not to affect adjacent areas of the coated product.

[0018] - the width of the print head measured perpendicular to the track direction is greater than or equal to the width of the coating strip to be applied, the width of the coating strip also being measured perpendicular to the track direction; and, among the nozzles selected during the selection step, only those nozzles are activated which are arranged facing the route of the coating strip on the surface to be coated.

[0019] - Information on the relative direction and speed of the print head with respect to the surface to be coated is provided to the electronic controller by the controller of the robot allowing the relative movement of the print head and the surface to be coated.

[0020] - Information on the relative direction and speed of the print head with respect to the surface to be coated is provided to the electronic controller by accelerometers or inertial devices mounted on the robot allowing relative movement of the print head and the surface to be coated.

[0021] Secondly, the present invention relates to an apparatus for applying a bead of a paint product to a surface to be coated, the apparatus comprising a print head equipped with a plurality of nozzles, each nozzle being centered on a central axis; a robot that allows the print head and the surface to be coated to move relative to each other, non-rotatably, along a trajectory fixed relative to the surface to be coated, about an axis parallel to the central axis of the nozzle; and a controller for each nozzle. According to the invention, the controller is configured to select and activate some of the nozzles of the print head at a point on the trajectory, based at least on the trajectory direction at that point and / or based on a previous point on the trajectory reached by the print head and the trajectory direction at that previous point.

[0022] The device can implement the method of the present invention and has the same advantages as the method of the present invention.

[0023] Advantageously, the print head nozzles are arranged on at least one circular arc, and preferably the body of the print head has a circular cross-section. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be better understood and its advantages will become apparent from the following description of six embodiments of the method and apparatus according to the principles of the present invention, given as examples with reference to the accompanying drawings, which are as follows:

[0025] Figure 1 is a front schematic diagram of an apparatus of the present invention configured to implement the method of the present invention;

[0026] Figure 2 It is used Figure 1 The schematic diagram of the principle of the device for applying a mastic strip according to the first application method of the present invention;

[0027] Figure 3 Similar to Figure 2 , showing an apparatus and a smearing method according to a second embodiment of the present invention;

[0028] Figure 4 Similar to Figure 2 , showing a coating device and method according to a third embodiment of the present invention;

[0029] Figure 5 is a schematic diagram of a coating apparatus showing a coating strip to be made and a print head prior to implementing the fourth method of the present invention;

[0030] Figure 6 During the implementation of the fourth method of the present invention Figure 5 A diagram of the trajectory of the nozzle relative to the coating strip in the device shown;

[0031] Figure 7 is a schematic diagram of a fifth coating method for forming a coating strip in a fifth apparatus of the present invention; and

[0032] Figure 8 Similar to Figure 7 , which is equivalent to implementing the sixth method of the present invention. DETAILED DESCRIPTION

[0033] Figure 1 and 2 The device 1 shown is used to apply a bead C of adhesive to an object O, in this embodiment a motor vehicle body. More precisely, in this embodiment, the device 1 can produce a bead C of adhesive for fixing a windshield to a surface S of a motor vehicle body.

[0034] As a variant, the object to be coated may be a part of a motor vehicle body, such as a door or a bumper, or more generally any object that can be coated, such as a portion of an aircraft fuselage or the body of a household appliance, these examples being non-limiting.

[0035] As a variant, the product of smearing is paint. In this case, coating strip C can be the contrasting color band on the motor vehicle body.

[0036] The device 1 has a conveyor belt 2, which is used to move along the Figure 1 The object O is transported through the conveying axis X2 which is perpendicular to the plane of the conveying axis.

[0037] The device 1 also has a coating head 10, which is mounted at the end of an arm 22 of a multi-axis robot 20 arranged near the conveyor belt 2.

[0038] The device 1 also has an electronic controller 24 capable of controlling the robot 20, and an electronic controller 30 capable of controlling the application head 10 carried by the device.

[0039] The coating head 10 has a plurality of nozzles 12, which are identical to one another and are mounted on one end face of a rigid parallelepiped body 14 of the printing head. For example, the nozzles may be of the type described in DE 10 2009 029 946 A1. Other nozzle types may also be used, depending on the properties of the coating product to be applied, in particular its viscosity.

[0040] The central axis of the printhead 10 is designated A10. The central axis of the printhead passes through the center of the surface of the main body 14. The nozzles 12 are disposed on the main body 14 and face the surface to be coated S when the printhead is activated to apply the coating product. The central axis of the nozzle 12 is designated A12 and is located at the center of the jet of coating product ejected from the nozzle. Each nozzle 12 is centered on its central axis A12. The nozzle central axis A12 is parallel to the central axis A10 of the printhead.

[0041] The electronic controller 30 is configured in particular for controlling the activation of the individual nozzles 12. The electronic control device 30 of the nozzles does not necessarily have to be arranged in the robot 20.

[0042] Information about the relative direction and relative speed of the print head 10 with respect to the surface to be coated S is provided by the controller 24 of the robot 20 to the electronic controller 30 .

[0043] As a variant, the controller 24 and the controller 30 may coincide.

[0044] Especially if Figure 2 As shown, the surface S to be coated is flat and parallel to the plane of the figure. Figure 1 and 2 In the embodiment shown, when producing a coating strip C of a paint product on the surface of a motor vehicle body O, the print head 10 moves along a trajectory T. This trajectory T is parallel to the surface S to be coated and is therefore flat in this embodiment. Figure 2 Oriented in the direction of arrow F1, Figure 2The directions of the trajectories are shown for the different points P. The trajectory T is separated from the surface to be coated S by a distance constituted by the distance used to apply the paint product.

[0045] In practice, the track T extends substantially relative to the center of the strip C to be produced and may be curved. Figure 2 In FIG, the trajectory T includes a curve corresponding to a curved area of ​​the coating strip C. The trajectory T is a curve along which the print head moves to apply the coating strip C. The curve can be straight, such as Figure 2 As shown, or zigzag, that is, three-dimensional.

[0046] In this Figure 2 In FIG. 1 , the print head 10 is shown at four positions along the track T, that is, the print head 10 follows the track T in the direction of arrow F1, located at Figure 2 The first position on the lower left faces the straight edge segment of the coating strip C, the second position is at the entrance of the curve, the third position is at the exit of the curve, and the fourth position faces the straight edge segment of the coating strip C defined after the curve.

[0047] like Figure 2 As shown, there are 25 nozzles 12 on the main body, arranged in an array of five rows and five columns with five nozzles each on a square surface, with the axis A12 of each nozzle being perpendicular to the plane of the figure. Figure 1 In FIG, the nozzle is shown extending from the body 14. However, the nozzle can be fully integrated into the body and flush with the square surface.

[0048] In order to simplify and optimize the axis of the robot 20, the movement of the main body 14 of the print head 10 along the trajectory T is performed by a combination of linear translation and circular translation, that is, the main body 14 is translated along the curved trajectory T, but the main body 14 does not rotate around the central axis A10 of the main body passing through its geometric center 142, or does not rotate around an axis parallel to the axis A10 and passing through another point of the main body 14.

[0049] exist Figure 2 In FIG, the black nozzles 12 represent active nozzles during the movement of the main body 14 along the trajectory T, while the white nozzles represent inactive nozzles. “Active” means that the nozzles eject the coating product as the print head 10 moves. “Inactive” means that the nozzles do not eject the coating product during the movement.

[0050] In order to ensure the correct application of the coating product used to form the coating strip C, the nozzles 12 are selected according to the position of the print head 10 along the trajectory T, that is, according to the point P of the trajectory in which a given point of the print head is located, in this embodiment, its geometric center. In practice, the position of the print head 10 along the trajectory T is determined by determining the position of the center 142 or other significant point of the body 14 along said trajectory.

[0051] The trajectory T is assumed to be such that, at any point P, in particular with respect to the direction defined by the tangent to the trajectory at that point and indicated by the arrow F1, the trajectory is known to the electronic controller 30. At a trajectory point P, the electronic controller 30 can determine a straight line D perpendicular to the trajectory direction, such as Figure 2 The four printhead positions are shown in Figure 1.

[0052] Alternatively, trajectory T need not be known in advance by electronic controller 30, but rather by electronic controller 24 of robot 20. If print head 10 is mounted on robot 20, its direction and speed of movement can be determined using an accelerometer or a central inertial device mounted on the print head. This accelerometer or central inertial device can be used to determine the print head's movement, allowing for local reconstruction of the trajectory T followed by the print head in real time. In this case, a line D perpendicular to the direction of trajectory T can also be determined at each point P on the trajectory.

[0053] In each case, an axis Z extending from the center of the print head to the surface to be coated S is defined on the path at a point P. This axis Z is perpendicular to Figure 2 The movement of the body 14 of the print head 10 along the trajectory T is performed by translation, which corresponds to a movement without rotation about the Z axis.

[0054] Controller 30 selects a nozzle group from nozzles 12 whose trajectory on smear C is as close as possible to line D. The nozzles of this nozzle group are labeled 12A, and the other nozzles of the print head are labeled 12B. In practice, nozzles 12A are arranged so that a regression line related to the position of nozzles 12A is as close as possible to line D. Here, nozzles 12A are arranged in a row L12.

[0055] exist Figure 2 In the illustrated embodiment, in the first position of the print head, the selected nozzle group 12A corresponds to a row of nozzles 12 formed on the main body 14. Therefore, line L12 is the center line of the row, which is a straight line. In the second position, the selected nozzle group 12A corresponds to a diagonal line of the nozzle array 12. Therefore, line L12 is the center line of the diagonal line, which is also a straight line. In the third position, the selected nozzle group 12A is shown on the surface of the main body 14 as a dotted line L12, which has a regression line D12, which is closest to the line D perpendicular to the trajectory T from the lines that can be formed in the nozzle array 12. In the fourth position, the selected nozzle group 12A corresponds to a column of the nozzle array 12. Therefore, line L12 is the center line of the column, which is also a straight line. Figure 2In the first, second and fourth positions of the print head shown, line L12 coincides with its regression line D12 and with line D. In the third position, dotted line L12 approximates regression line D12 and is parallel to line D, but does not coincide with it.

[0056] In the corresponding Figure 2 In the two straight sections of the coating strip C shown in the first and fourth positions, two selected groups of nozzles 12A are formed by two perpendicular lines of nozzles, ie a row of nozzles 12 in the first configuration and a column of nozzles 12 in the second configuration.

[0057] In this embodiment, all selected nozzles 12A are activated at one point P to apply the paint product. Thus, the nozzles 12A are at Figure 2 The middle is black.

[0058] Thus, the method comprises selecting certain nozzles, namely nozzle 12A, at a point P, after a step of activating these nozzles, in the direction F1 of said point according to trajectory T, which allows the coating product to be applied efficiently and economically with enough nozzles to prevent the occurrence of uncoated areas or "gaps" in the coating bead C, but without overusing the coating product or making the coating bead too thick.

[0059] According to only Figure 2 In one embodiment of the second position of print head 10, nozzle 12A is determined by taking into account a previously reached trajectory point P' and trajectory direction F1' at the previous point P'. This approach allows for the identification of nozzles 12A that were previously active at the previous point P' and nozzles 12A that should be active at point P. This variant embodiment is also applicable to other print head positions along trajectory T and other embodiments described below.

[0060] The variant implementation using the previous point P′ and the previous direction F1 ′ can replace or supplement the basic approach using only the direction F1 at the point P.

[0061] The selection of the nozzle 12A within the array of nozzles 12 can be performed before the production of the coating strip C is performed, once the trajectory T is known. In other words, the step of selecting the nozzle 12A can be performed before using the robot 20 and applying the print head 10.

[0062] In this case, the area of ​​the surface S can also be taken into account when selecting the nozzle 12A. This results in a modification of the linear regression algorithm for calculating the straight line D12 from the line L12, taking into account the influence of the nozzle on the surface S.

[0063] Furthermore, the strips can then be provided with right angles, forming a rectangular array, for example with no overlapping areas at the inner corners due to the 90 degree change of direction.

[0064] Alternatively, the selection and activation steps can follow one another. In particular, the nozzle 12A to be activated can be selected at each advancement step of the robot 20 arm 22 according to the trajectory T stored in the electronic controller 30. Real-time velocity information can be obtained at the robot tool center, along the axes of an orthogonal reference coordinate system relative to the part to be coated. By integrating these velocity values, the change in print head position relative to the part can be calculated. This approach allows for the actual print head position during application of the coating strip C and for possible adjustments to trajectory T based on this actual position.

[0065] The application programmer can choose how to determine which of the nozzles 12 should constitute the nozzle 12A to be activated, and how to approximate the straight line D perpendicular to the trajectory T with a line of nozzles. For this purpose, a regression method (linear or non-linear, polynomial, etc.) can be used, including error calculation (quadratic or non-quadratic, least squares method, etc.).

[0066] In the following and Figure 3 In the illustrated second to fifth embodiments of the present invention, components similar to those of the first embodiment are designated by the same reference numerals.

[0067] The surface S to be coated is still assumed to be planar and parallel to Figure 3 plane, the movement of the print head along its trajectory T is also planar, as defined in the first embodiment, and is carried out by a combination of translations parallel to the surface S to be coated, as defined in the first embodiment, without rotating around the central axis A10 of the print head, or around an axis parallel thereto, or around the axis Z defined in the first embodiment.

[0068] Below, we mainly explain these embodiments and Figure 1 and 2 The difference between the embodiments, while the following reference Figure 3 The method described can be used Figure 1 The device 1 is implemented as long as the device 1 is applicable, especially with respect to the structure 10 of the print head.

[0069] exist Figure 3 In the embodiment shown, the main body 14 of the printhead 10 is cylindrical and has a circular cross-section, and maintains twelve nozzles 12 distributed over a disc-shaped surface. No nozzle is located at the geometric center 142 of the main body 14 of the printhead 10. Figure 3 Five positions of the print head 10 are shown, and straight lines D perpendicular to the direction F1 of the track T are marked at track points P corresponding to the five positions.

[0070] The nozzles 12 are distributed on a circle centered at the geometric center 142 of the main body 14, which is considered to be aligned with a point P of the trajectory T. In this embodiment, the selected nozzles 12A are nozzles located in front of the line D relative to the line D along the trajectory T in the direction of advance of the print head 10. Therefore, in this embodiment, the line L12 passing through the selected nozzle 12A closest to the other unselected nozzles 12B is the diameter of the main body 14 of the print head 10, which overlaps the line D at each point P of the trajectory. The selected nozzles 12A also include the nozzles located on the line L12.

[0071] Line L12 defines a set of nozzles 12A relative to nozzles 12B. Since this line is the diameter of body 14, it coincides with its regression line D12.

[0072] The unselected nozzles 12B are located behind the line L12 and the straight line D along the trajectory T in the feeding direction of the print head.

[0073] In this embodiment, the nozzles 12A selected and activated are distributed on an arc C12, which is positioned in front of the body 14 moving along the trajectory T relative to the line L12, so that the paint product can be applied smoothly over the width of the paint coating line C without being too thick, which would be the case if all print head nozzles 10 were activated along the entire trajectory.

[0074] Since the movement of the main body 14 of the print head 10 along the trajectory T is performed by linear or circular translation, the nozzles 12A selected and activated for applying the coating product to form the coating bead C are Figure 3 Variations are made between the five configurations shown.

[0075] exist Figure 4 In the illustrated embodiment, the body 14 of the print head 10 is also cylindrical and has a circular cross-section and is centered on a geometric center 142 corresponding to one nozzle 12, as in the first embodiment.

[0076] In this embodiment, the nozzles 12 are distributed over the entire surface of the body 14, rather than being arranged in a single circle. In fact, the nozzles are distributed over a disk-like surface in a plurality of concentric circles centered on the center 142.

[0077] Still in this embodiment, based on the movement of the print head 10 in linear and circular translation along the trajectory T, different groups of nozzles 12A are selected according to the direction F1 of the trajectory T. The groups of nozzles 12A are defined relative to the other nozzles 12B by a line L12 which, at each point P of this trajectory T, is perpendicular to a line D in the direction of the trajectory T.

[0078] In this embodiment, the group of selected nozzles 12A corresponds to approximately half of the disk, and the selected nozzles 12A are arranged on an arc of a circle. In the first and fourth positions, in which the print head moves in a straight line, the line L12 is straight and extends along the diameter of the main body 14, overlapping the straight line D at the trajectory point P involved. In the second and third positions, corresponding to a turn and exiting the turn, respectively, the selected nozzles 12A are arranged at the edge, and the unselected nozzles 12B extend along the line L12, which is curved, that is, not straight, but approximates the straight line D perpendicular to the trajectory T. In this embodiment, the line L12 in the second and third positions is a dotted line formed by a series of straight line segments, as in Figure 2 Here, line L12 is selected from a line that can be defined by nozzle 12 on body 14, such as a line whose regression line D12 is as close as possible to line D. First, the programmer can select an approximation method.

[0079] In this embodiment, the print head holds twenty-one nozzles.

[0080] Figure 5 and 6 The present invention shows a case where a coating strip C is produced using a print head 10, the main body 14 of the print head being cylindrical and having a circular cross-section and holding eight nozzles 12 distributed around the periphery of a disc-shaped surface. The geometric center of the main body 14 is marked 142 and moves along a predetermined trajectory T, with its feed direction marked by arrow F1, as in the previous embodiment.

[0081] The geometry of the trajectory T is such that the strip C has a complex shape with a large first turn and a sharper second turn.

[0082] like Figure 6 As shown, the solid line represents the path of the selected nozzle 12A, and the dotted line represents the path of the unselected nozzle 12B. The nozzle can be selected according to the feeding direction of the main body 14 along the trajectory T.

[0083] The eight nozzles 12 are marked with different reference numbers, from 121 to 128. Figure 6In FIG, the trajectory T12i of nozzle 12i is labeled i, where i ranges from 1 to 8. On each trajectory T12i, the path of nozzle 12i is shown as a dashed line when nozzle 12i is not selected, thus representing the nozzle 12B type described above, and as a solid line when selected, thus representing the nozzle 12A type described above. For example, trajectory T121 shows nozzle 121 being selected only from the beginning of the terminal straight segment of trajectory T after the second turn. Conversely, trajectory T122 shows nozzle 122 being selected at the beginning of trajectory T until the first turn, then entering the final straight segment after the second turn. Trajectory T123 of nozzle 123 shows it being selected during the first straight segment of trajectory T, for the majority of the first turn, and then being deselected. Trajectory T124 of nozzle 124 shows it being selected at the beginning, until the middle of the segment between the first and second turns of trajectory T, and then being deselected. Trajectory T125 of nozzle 125 shows it being selected until the beginning of the second turn. The trajectory T126 of nozzle 126 shows that it is selected from the start of the first turn until it leaves the second turn. The trajectory T127 of nozzle 127 shows that it is selected from the exit of the first turn until the end of the movement. The trajectory T128 of the eighth nozzle shows that it is selected from the end of the first turn until the end of the movement.

[0084] In this case, the nozzles 12i constituting the nozzles 12A selected for activation at a point P on the trajectory T are understood to be nozzles positioned toward the front of the movement of the print head 10 in a manner comparable to that of the second embodiment, however, the number of nozzles is different and a more elaborate implementation is required due to the more complex geometry of the coating strip C. Thus, in this embodiment, at the beginning of the trajectory, the nozzles 12A selected are nozzles 122 to 125. At the entrance to the first turn, the nozzles 12A selected are nozzles 122 to 126. Between the first and second turns, the nozzles 12A selected are nozzles 125, 126, and 127. At the exit of the second turn, the nozzles 12A selected are nozzles 121, 122, 127, and 128.

[0085] The width of the coating strip C to be applied is designated Lc and is measured perpendicularly to the direction F1 of the track T, assuming that this width is constant. The useful width of the print head, i.e., the installed width of the nozzles 12j on the body 14, is designated L10 and is also measured perpendicularly to the direction of the track T. Here, the width L10 is equal to the diameter of the body.

[0086] Figure 6It is shown that some nozzles 12i can be selected at a point P of the trajectory T because their trajectory T12i is a continuous line when they are not facing the path of the coating strip C to be produced. This is the case, for example, for nozzles 122 and 125 in the first part of the trajectory before the first turn. This is because the width L10 is definitely greater than the width Lc.

[0087] In this case, not all selected nozzles 12A are necessarily intended to be activated. An additional control step can be implemented, in which a check is performed to determine whether a given nozzle 12i belonging to the group of selected nozzles 12A is actually facing the path of the coating strip C on the surface to be coated S, i.e., the area of ​​the surface to be coated S. If this is the case, activation of the nozzle 12i is confirmed and the nozzle is activated. Otherwise, activation is prevented.

[0088] exist Figure 6 In the embodiment shown, nozzles 126, 127 and 128 are selected between the two turns but are not activated because the coating product from these nozzles is beyond the path of the coating bead C on the surface to be coated S. The same applies to nozzles 122, 126 and 127 after the second turn.

[0089] Thus, the present invention makes it possible to use the same print head 1 to apply swathes C of different widths Lc that are less than or equal to the useful print head width L10, since the activation of the selected nozzles 12A takes into account the width Lc of the swathe C at each point P of the trajectory.

[0090] If the width Lc varies along the coating strip C, the above-mentioned related tests are adjusted.

[0091] exist Figure 7 and 8 In the embodiment of FIG. 1 , the main body 14 of the print head 10 holds sixteen nozzles 12j, j being 1 to 16, which are distributed around the periphery of a disk-shaped surface of the main body 14. Figure 7 and 8 In FIG. 1 , the area of ​​the coating strip C applied by the nozzle 12j is marked with Z12j, where j is 1 to 16.

[0092] Figure 7 Shown with the geometric structure of Figure 5 and 6 The coating strip C shown has the same geometric structure and consists of a series of coating strip segments consisting of areas Z12j. This is possible because at each point of the trajectory T, some nozzles 12j are selected to constitute the selective nozzles to be started at that point in the sense of the selective nozzles 12A of the first embodiment.

[0093] It can be seen that not all nozzles are used to form the coating strip C. In fact, Figure 7There is no region in φ corresponding to the nozzle 121 or to the nozzle 123 .

[0094] Depend on Figure 7 It can be seen that outside the first turn, there are large gaps between areas Z125 and Z126 on the one hand and between areas Z126 and Z127 on the other hand, while areas Z1213, Z1214, Z1215 and Z1216 overlap on the inside of the second turn.

[0095] In the case of sealing strips, the goal is to have a completely coated surface. In the case of adhesive or soundproofing strips, the goal is to find the amount of coating that can be applied.

[0096] This problem is in implementation Figure 8 This problem is solved in the method shown, in which the width L126 of the zone Z126 is locally increased at the ends of this zone, along the direction of movement of the print head along the trajectory T, in order to avoid the appearance of "gaps" in the coating strip C. To this end, the activation of the nozzles 126 can be modified in the corresponding zones outside the first turn, for example by increasing their activation frequency and / or the opening time of their discharge valves.

[0097] Likewise, the nozzles 1213, 1214 and 1216 are started later from the exit of the second turn so that only the coating product discharged from the nozzle 1215 is applied in this portion of the coating strip C to prevent Figure 7 Visible overlaps can lead to too thick a coating strip C. Therefore, in this portion of the coating strip C, the width L1213, L1215 and L1216 of each zone Z1213, Z1215 or Z1216 is temporarily reduced to zero, taking into account the distance between these zones and the adjacent zone Z1214, by, for example, reducing to zero their activation frequency and / or the opening time of their discharge valves.

[0098] Likewise, the end of zone Z12j can be pre-processed, ie its width can be reduced to zero, for example by reducing its activation frequency and / or the opening time of its outlet valve to zero, so as not to affect adjacent zones.

[0099] According to an embodiment of the present invention that is not shown, a zone Z12j can be gradually transformed from zero width to nominal width by, for example, gradually changing the activation frequency and discharge time of each nozzle.

[0100] In the above embodiments, the coating area width of the selected nozzles is adapted to be adjusted by regulating the output of coating product from each nozzle, as controlled by the activation frequency and / or opening time of the associated discharge valve.

[0101] The nozzle firing frequency may be controlled by a piezoelectric assembly or other comparator device such as a solenoid valve.

[0102] Figure 7 and8 The method also allows for the effective width L10 of the print head 10 to be greater than the width Lc of the coating strip C when certain selected nozzles are not facing the trajectory of the coating strip C on the surface to be coated S. This is particularly the case for nozzles 121 and 128, which are located on the side edges of the portion of the trajectory T of the print head before the first turn.

[0103] Whatever the embodiment, the choice of nozzle 12A starting along the trajectory T, depending on the trajectory direction, allows the coating product to be applied in a manner adapted to the geometry of the coating strip C to be produced, while maintaining a relatively simple method of movement of the print head 10, since a linear or circular translation is used instead of rotating the print head around its central axis or an axis parallel thereto, such as the Z axis.

[0104] In the above embodiment, the selection of the nozzles 12A and their activation are automatically performed in the electronic controller 12 of the nozzles, whether or not this controller is integrated in the robot 20, e.g. Figure 1 The controller 30 of the device 1 is shown to be inside or mounted outside the robot.

[0105] In the case where the surface S to be coated is curved, i.e. not straight, the trajectory T is adjusted and does not need to be straight. In addition, the print head is pivotable during its movement about two transverse axes B10 and C10 defined by the body 14 and perpendicular to the axis A10 and to each other. In this case, even if the movement of the print head in the surface reference coordinate system is not a simple combination of translation, the print head 10 does not rotate about its central axis A10. This allows the surface 14 of the print head on which the nozzles 12 are mounted to be mounted generally parallel to the surface to be coated S so that on curved areas, for example Figure 1 Onto the attachment area of ​​the windshield shown, a coating strip C is deposited.

[0106] According to an embodiment of the invention (not shown), the print head 10 is fixed and the surface to be coated S is moved by a robot facing the nozzle 12 in a linear or circular translational motion. In this case, the print head 10 and the nozzle 12 move along a trajectory T in the reference coordinate system of the surface to be coated S. In this case, if the electronic controller 30 does not know the trajectory T in advance, the robot supporting the part to be coated can be equipped with an accelerometer or a central inertial device, allowing it to reconstruct the trajectory T followed by the print head 10 locally in real time in the reference coordinate system of the surface to be coated S. In this case, because the print head is fixed, the robot is programmed to keep the mid-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.

[0107] The robot for ensuring the relative movement between the print head and the surface to be coated, whether the surface or the print head is fixed during coating, may be of any known type, such as Figure 1 Multi-axis, Scara or reciprocating types as shown.

[0108] According to another embodiment of the invention, not shown, the nozzles 12 or some of them are arranged in an arc of a circle, while the body 14 does not have a circular cross section.

[0109] The accompanying drawings illustrate printheads of the present invention having 8, 12, 16, 21, or 25 nozzles. Other nozzle counts may be employed regardless of the distribution structure on the body 14. However, a nozzle distribution in one or more circular arcs is particularly advantageous, as illustrated in the second through sixth embodiments.

[0110] The present invention shows nozzles 12 distributed in rows and columns or in an arc, however, other distributions may be used provided that the selected nozzles lie in a line or are part of a group of nozzles defined by a line of their linear regression lines as defined above.

[0111] The above-described embodiments and implementations can be combined with one another to form new embodiments of the invention within the scope of the appended claims.

Claims

1. A method for applying a stripe (C) of a coating product to a surface (S) to be coated using a print head (10) equipped with a plurality of nozzles (12), each nozzle being centered on a central axis (A12), the coating product being applied by relative movement of the print head along a trajectory (T) fixed relative to the surface to be coated, the print head and the surface to be coated being moved relative to each other without rotating the print head about an axis (A10) parallel to the central axis (A12) of the nozzles, the method comprising the step of selecting a number of nozzles (12A) for a point (P) of the trajectory (T) based on the number of nozzles (12A) at that point (P) and / or based on a previous point (P') of the track reached by the print head and the direction of the track (F1') at the previous point, and the method comprises the step of activating selected nozzles at this point (P), the selected nozzles (12A) being arranged in a row (L12) or part of a nozzle group defined by a line (L12), the line of return (D12) of which coincides with a line (D) perpendicular to the direction of the track (T) or as close as possible to a line perpendicular to the direction of the track in the line defined by the nozzles (12) of the print head (10), characterized in that The width (L126, L1213, L1215, L1216) of the area (Z126, Z1213, Z1215, Z1216) coated from the selected and activated nozzle (126, 1213, 1215, 1216) is adjusted according to the distance between the area and the adjacent area (Z125, Z127, Z1214) coated from other nozzles (125, 127, 1214).

2. The method according to claim 1, characterized in that The nozzles (12) of the print head (10) are arranged in rows and columns; and, during the selection step, nozzles (12A) of a portion of some rows and / or a portion of some columns are selected together for firing.

3. The method according to claim 1, characterized in that The nozzles (12) of the print head (10) are arranged on at least one circular arc; and, during the selecting step, the nozzles (12A) of a portion of the circular arc are selected together for firing.

4. The method according to claim 1, wherein The width (L126) of the coating zone (Z126) is adjusted by varying the feed activation frequency of the nozzles (126) that are selected and activated.

5. The method according to claim 1, wherein The width (L1213, L1215, L1216) of the area coated from the selected and normally activated nozzles (1213, 1215, 1216) is locally reduced to zero so as not to affect the adjacent coated product area (Z1214).

6. The method according to any one of the preceding claims, characterized in that The width (L10) of the print head, measured perpendicularly to the track direction (F1), is greater than or equal to the width (Lc) of the coating strip (C) to be applied, the width of the coating strip also being measured perpendicularly to the track direction; and, among the nozzles (12A) selected during the selection step, only those nozzles are activated which are arranged facing the path of the coating strip on the surface (S) to be coated.

7. The method according to any one of claims 1 to 5, characterized in that Information on the relative direction and speed of the print head (10) with respect to the surface (S) to be coated is provided to the electronic controller (30) by a controller (24) of a robot (20) that allows relative movement of the print head and the surface to be coated.

8. The method according to any one of claims 1 to 5, characterized in that Information on the relative direction and speed of the print head (10) relative to the surface (S) to be coated is provided to the electronic controller (30) by an accelerometer or inertial device mounted on a robot that allows relative movement of the print head and the surface to be coated.

9. Apparatus (I) for applying a bead (C) of a paint product to a surface (S) to be coated, the apparatus comprising: - a print head (10) equipped with a plurality of nozzles (12), each nozzle being centered on a central axis (A12); - a robot (20) allowing the 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 controller (30) for each nozzle, It is characterized by: The controller (30) is configured to select and activate some nozzles (12A) of the print head at a point (P) of a trajectory (T), wherein the width (L126, L1213, L1215, L1216) of the area (Z126, Z1213, Z1215, Z1216) coated from the selected and activated nozzles (126, 1213, 1215, 1216) can be adjusted according to the distance between the area and the adjacent area (Z125, Z127, Z1214) coated from other nozzles (125, 127, 1214).

10. The device according to claim 9, characterized in that The nozzles (12) of the print head (10) are arranged on at least one circular arc.

11. The device according to claim 10, characterized in that The body (14) of the print head has a circular cross-section.

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