EP3810429B1 - Facility for printing or coating surfaces of three-dimensional parts - Google Patents

Description

The present invention generally relates to the field of the treatment and coating of surfaces of parts by an automated installation, in particular the printing by projection of patterns on surfaces of complex shapes, in particular three-dimensional, and relates to an installation of printing and/or coating of such surfaces of parts, preferably by implementing printing means of the ink jet type.

The parts concerned may in particular consist of automobile interior trim parts.

In a known manner and as illustrated, for example, by the publications OF 10 2012 212 469 A1 , US 2009/0167817 A1 , EP 2 873 496 A1 , And EP 0 931 649 A1 , to print a part by ink-jet type printing means, the printing head which ejects the coating substance, such as ink, can be moved by a robotic arm relative to a part which remains fixed.

However, the printing means, which most often incorporate a four-color assembly, are generally bulky, and it is then complicated to move them, especially at high speed. This is all the more true when these printing means are, in addition, associated with a module for at least partial drying of the drops of the substance deposited on the surface, placed directly under the printing head. In addition, the printheads may be subject to disturbances or position variations due to the rapid movement of the robotic arm. To limit these disturbances, it is then necessary to limit the speed of movement of the robotic arm, which reduces the rate, as well as industrial efficiency. Furthermore, sudden variations in the orientation of the print head have the effect of impacting the quality of the print. Indeed, inside the print head the air is in a slight depression to prevent the substance from flowing out by gravity. However, sudden variations in orientation have the consequence of modifying the balance between the atmospheric pressure and the pressure inside the printhead, and therefore of disturbing the ejection of the substance. Finally, it is also tricky to embed the printhead substance supply unit on the robotic arm.

To overcome these drawbacks, it has been proposed, in particular by the applicant in its patent applications French n° 17 50260 , no. 17 51064 And no. 18 54024 , the implementation of installations in which the printing head and the drying means are fixed, that is to say immobile and static, and only the part is moved during printing, being mounted on a multi-axis robotic arm.

Also in these installations, the printing means consist of a single quadri-chromic color printing head which, seen from the front, generally has a configuration of the nozzles or ejection orifices of the different colors as shown figure 1 (B=black; Y=yellow; C=cyan; M=magenta).

These orifices are arranged in vertically superimposed lines (Z axis) with alternating projected colors and the spacing "e" between nozzles of the same color, belonging to two successive lines of nozzles of the stack, determines the printing resolution .

However, such a four-color printhead has a certain number of drawbacks, as indicated below.

Thus, it has a large bulk (height) in the Z direction (generally the vertical direction). This characteristic leads to print quality and homogeneity problems due to variations in the speed of movement of the part (attached to the robot arm). Moreover, due to the alternation by color of the rows of nozzles, the relatively large distances separating two successive rows delivering the same color make it difficult for the mutual synchronization of these rows of nozzles of the same color to be mutually synchronized. The resulting print quality on three-dimensional surfaces is therefore not optimal. Finally, the order of succession of the colors is physically imposed by the allocation of the nozzle lines by color and the limited resolution of the quadri-chromic head makes it necessary to carry out several printing passes to obtain a good quality of printing, d resulting in a significant waste of time.

By document US 9,266,354 , there is known a printing installation comprising a plurality of bi-chromatic or monochromatic print heads and drying/cross-linking means mounted in a circular arrangement on a fixed support structure.

The piece to be decorated is, for its part, moved in front of the printing heads and the drying/cross-linking means, by a support device comprising a first unit for moving in translation and second and third rotational displacement units, around pivot axes which are not parallel to each other and one of which coincides with the translation axis of the first unit.

This installation has a complex and relatively bulky structure, with in addition a significant limitation in terms of varieties of shapes of three-dimensional surfaces that can be treated. Finally, it has a multitude of printing and drying positions, corresponding to the different positions of the aforementioned heads and means.

The document JP 2002 084407 A discloses an installation for printing surfaces of three-dimensional parts. The installation comprises a part support, capable of receiving and holding a part to be decorated and mounted on a displacement device, and sensor means, capable of detecting the three-dimensional shape of the part.

The object of the present invention is to overcome at least the main drawbacks stated above.

• un support de pièce, apte à recevoir et à maintenir une pièce à décorer ou à revêtir et monté sur un dispositif de déplacement à au moins cinq degrés de liberté, tel que par exemple un bras robot six axes,
• des moyens d'impression par projection d'encre ou analogue, consistant en au moins une tête d'impression,
• des moyens capteurs, aptes à mesurer des paramètres de positionnement et/ou de déplacement de la pièce, en particulier des vitesses de déplacement et/ou des coordonnées de positionnement,
• éventuellement des moyens de séchage et/ou de réticulation, au moins partiel(le), des substances projetées sur la surface de la pièce à décorer,
• des moyens de calcul, de gestion et de commande aptes et destinés à exploiter les signaux délivrés par les moyens capteurs et à commander au moins les moyens d'impression et le dispositif de déplacement,

• les moyens d'impression, les moyens capteurs et les éventuels moyens de séchage étant arrangés côte à côte, de manière superposée, sur une structure support fixe, tel qu'un socle, un montant, un portique ou analogue,
• le dispositif de déplacement et la structure de support étant disposés mutuellement en regard et un repère spatial étant affecté à ladite structure support fixe, avec un premier axe déterminant la distance entre le dispositif de déplacement et ladite structure de support, un deuxième axe correspondant à la direction d'empilement des moyens d'impression, capteurs et éventuellement de séchage et un troisième axe perpendiculaire aux deux axes précédents,
• dans laquelle les moyens d'impression consistent en au moins deux têtes d'impression monochromatiques ou bi-chromatiques mobiles, en rotation et/ou en translation, avec au moins un degré de liberté, lesdites têtes pouvant être déplacées sélectivement, une par une, vers une position spatiale déterminée autorisant l'impression de la surface de la pièce, ce sous le contrôle des moyens de calcul, de gestion et de commande, et en accord avec des données préprogrammées, par exemple un programme d'impression, déterminant également le déplacement de la pièce relativement à la structure support et à la position spatiale déterminée.

To this end, it relates to an installation for printing and/or coating the surfaces of parts, in particular three-dimensional surfaces, this installation essentially comprising:

• a part support, capable of receiving and holding a part to be decorated or coated and mounted on a movement device with at least five degrees of freedom, such as for example a six-axis robot arm,
• means for printing by ink projection or the like, consisting of at least one print head,
• sensor means, capable of measuring positioning and/or displacement parameters of the part, in particular displacement speeds and/or positioning coordinates,
• possibly means for drying and/or cross-linking, at least partially, of the substances projected onto the surface of the part to be decorated,
• calculation, management and control means able and intended to exploit the signals delivered by the sensor means and to control at least the printing means and the displacement device,

• the printing means, the sensor means and any drying means being arranged side by side, in a superimposed manner, on a fixed support structure, such as a base, an upright, a gantry or the like,
• the displacement device and the support structure being mutually arranged facing each other and a spatial reference being assigned to said fixed support structure, with a first axis determining the distance between the moving device and said support structure, a second axis corresponding to the stacking direction of the printing means, sensors and possibly drying and a third axis perpendicular to the two previous axes,
• in which the printing means consist of at least two monochromatic or bi-chromatic printing heads which are movable, in rotation and/or in translation, with at least one degree of freedom, said heads being able to be moved selectively, one by one, towards a determined spatial position authorizing the printing of the surface of the part, this under the control of the calculation, management and control means, and in accordance with preprogrammed data, for example a printing program, also determining the movement of the part relative to the support structure and to the determined spatial position.

• la figure 2 est une vue schématique d'ensemble en élévation latérale d'une installation d'impression selon un mode de réalisation de l'invention ;
• les figures 3A à 3C sont des vues partielles en élévation latérale (3A), en élévation frontale (3B) et de dessus (3C) du détail A de la figure 2, correspondant à la partie de l'installation regroupant les moyens d'impression, capteurs et de séchage, en accord avec une première variante de réalisation de l'invention (déplacement en translation, selon un axe, des têtes d'impression alignées) ;
• les figures 4A et 4B illustrent, avec des vues similaires à celle de la figure 3B, deux séquences consécutives d'impression avec deux têtes monochromatiques de couleurs différentes ;
• les figures 5A à 5C sont des vues partielles en élévation latérale (5A), en élévation frontale (5B) et de dessus (5C) du détail A de la figure 2, en accord avec une seconde variante de réalisation de l'invention (répartition circulaire et déplacement en rotation autour d'un axe des têtes d'impression) ;
• les figures 6A et 6B sont des vues partielles en élévation latérale (6A) et frontale (6B) du détail A de la figure 2, en accord avec une troisième variante de réalisation de l'invention (déplacement en translation, selon deux directions perpendiculaires, des têtes d'impression alignées) ;
• la figure 7 est une vue en perspective et par transparence d'une partie du détail A de la figure 2, montrant les moyens d'impression et leur logement dans la structure support, en accord avec une quatrième variante de réalisation de l'invention (les têtes d'impression étant déplaçables selon trois directions mutuellement orthogonales) ;
• la figure 8 illustre, schématiquement et de manière comparative, respectivement les distances D et d entre rangées de buses de projection d'une même couleur, en relation avec une tête d'impression quadri-chromique selon l'état de la technique et en relation avec une tête d'impression monochromatique selon l'invention ;
• les figures 9A et 9B illustrent schématiquement les écarts entre deux rangées de buses et les écarts résultants en termes de résolution d'impression sur une surface non plane, pour une tête quadri-chromique de l'état de la technique (9A) et pour une tête monochromatique selon l'invention (9B) ;
• la figure 10 illustre schématiquement, au moyen de vues de face des structures supports d'une illustration d'impression, les différences d'encombrement vertical entre une tête quadri-chromique de l'état de la technique (à gauche) et une tête monochromatique, simple ou double (bi-chromatique), selon l'invention (à droite), et,
• la figure 11 illustre schématiquement sous la forme d'une vue d'ensemble partielle un autre mode de réalisation d'une installation d'impression selon l'invention.

The invention will be better understood, thanks to the description below, which relates to preferred embodiments, given by way of non-limiting examples, and explained with reference to the appended diagrammatic drawings, in which:

• there picture 2 is a schematic assembly view in side elevation of a printing installation according to one embodiment of the invention;
• THE figures 3A to 3C are partial side elevation (3A), front elevation (3B) and top (3C) views of detail A of the picture 2 , corresponding to the part of the installation grouping together the printing, sensor and drying means, in accordance with a first variant embodiment of the invention (movement in translation, along an axis, of the aligned printing heads);
• THE figures 4A and 4B illustrate, with views similar to that of the Figure 3B , two consecutive printing sequences with two monochromatic heads of different colors;
• THE figures 5A to 5C are partial side elevation (5A), front elevation (5B) and top (5C) views of detail A of the figure 2 , in accordance with a second alternative embodiment of the invention (circular distribution and displacement in rotation about an axis of the printheads);
• THE figures 6A and 6B are partial side (6A) and front (6B) elevation views of detail A of the figure 2 , in accordance with a third alternative embodiment of the invention (movement in translation, in two perpendicular directions, of the aligned printing heads);
• there figure 7 is a perspective and transparent view of part of detail A of the figure 2 , showing the printing means and their housing in the support structure, in accordance with a fourth variant embodiment of the invention (the printing heads being movable in three mutually orthogonal directions);
• there figure 8 illustrates, schematically and in a comparative manner, respectively the distances D and d between rows of projection nozzles of the same color, in relation to a four-color printing head according to the state of the art and in relation to a head monochromatic printing according to the invention;
• THE figures 9A and 9B schematically illustrate the differences between two rows of nozzles and the resulting differences in terms of printing resolution on a non-flat surface, for a four-color head of the state of the art (9A) and for a monochromatic head according to invention (9B);
• there figure 10 schematically illustrates, by means of front views of the support structures of a print illustration, the differences in vertical size between a four-color head of the state of the art (on the left) and a monochromatic head, simple or double (bi-chromatic), according to the invention (on the right), and,
• there figure 11 schematically illustrates in the form of a partial overview another embodiment of a printing installation according to the invention.

• un support de pièce 3, apte à recevoir et à maintenir une pièce 2 à décorer ou à revêtir et monté sur un dispositif de déplacement 4 à au moins cinq degrés de liberté, tel que par exemple un bras robot six axes,
• des moyens 5 d'impression par projection d'encre ou analogue, consistant en au moins une tête d'impression 6 ou 7,
• des moyens capteurs 8, aptes à mesurer des paramètres de positionnement et/ou de déplacement de la pièce 2, en particulier des vitesses de déplacement et/ou des coordonnées de positionnement,
• éventuellement des moyens 9 de séchage et/ou de réticulation, au moins partiel(le), des substances projetées sur la surface 2' de la pièce 2 à décorer,
• des moyens 10 de calcul, de gestion et de commande aptes et destinés à exploiter les signaux délivrés par les moyens capteurs 8 et à commander au moins les moyens d'impression 7 et le dispositif de déplacement 4.

THE figure 2 And 11 show an installation 1 for printing and/or coating surfaces 2' of parts 2, in particular non-planar or three-dimensional surfaces, this installation 1 essentially comprising:

• a piece support 3, capable of receiving and holding a piece 2 to be decorated or coated and mounted on a displacement device 4 with at least five degrees of freedom, such as for example a six-axis robot arm,
• means 5 for printing by ink projection or the like, consisting of at least one print head 6 or 7,
• sensor means 8, capable of measuring positioning and/or displacement parameters of the part 2, in particular displacement speeds and/or positioning coordinates,
• possibly means 9 for drying and/or cross-linking, at least partially, of the substances projected onto the surface 2' of the part 2 to be decorated,
• calculation, management and control means 10 suitable and intended for exploiting the signals delivered by the sensor means 8 and for controlling at least the printing means 7 and the displacement device 4.

The printing means 7, the sensor means 8 and any drying means 9 are arranged side by side, superimposed, on a fixed support structure 11, such as a base, an upright, a gantry or the like.

The displacement device 4 and the support structure 11 are arranged opposite each other and a spatial reference X, Y, Z is assigned to said fixed support structure 11, with a first axis X determining the distance between the displacement device 4 and said support structure 11, a second axis Z corresponding to the direction of stacking of the printing means, sensors and possibly drying means 5, 8, 9 and a third axis Y perpendicular to the two preceding axes X and Z.

In accordance with the invention and as emerges from the figures 3 to 10 , the printing means 5 consist of at least two monochromatic 6 or bi-chromatic 7 mobile printing heads, in rotation and/or in translation, with at least one degree of freedom, said heads 6, 7 being able to be moved selectively , one by one, towards a determined spatial position PSD authorizing the printing of the surface 2′ of the part 2, this under the control of the calculation, management and control means 10, and in accordance with preprogrammed data, by example a printing program, also determining the displacement of the part 2 relative to the support structure 11 and to the determined spatial position PSD.

Thanks to the aforementioned arrangements, the invention makes it possible to overcome the drawbacks associated with a multicolor printhead of large size along the stacking axis of the means 5, 8, 9 (axis Z in the figures) and whose nozzle lines of the same color are consistently spaced.

In addition, the definition, for the different heads 6, 7 of the means 5, of a single spatial position PSD authorizing printing makes it possible to simplify and make more precise the kinematics of relative displacement and positioning of the different heads 6, 7 with respect to the part 2 in motion during the course of the printing.

Finally, by allowing lines of similar nozzles or ejection orifices 13, allocated to the same color, to be brought together, the resolution obtained will be significantly higher (cf. figures 8 to 10 ). The PSD position is normally aligned and immediately adjacent to those of the sensor and drying means 8 and 9 for greater constructive simplicity and better efficiency.

In the embodiment of the picture 2 , and in the variants of figures 3 to 7 , the printheads 6, 7 remain at least partially in the support structure 11 although they are movable relative to the latter.

In accordance with a first variant embodiment and as illustrated in the figure 3 , the printheads 6, 7 can be arranged side by side linearly along the third Y axis and be movable together in sliding along this Y axis, under the effect of a suitable translation actuator controlled by the calculation means 10 , management and control.

The different monochrome heads 6 can be part of the same module forming multiple head 5 in the form of a bar, and be arranged in line in a horizontal direction (Y axis in the figures), therefore with a vertical size (Z axis in the figures ) minimum. The guiding of the block of heads 6 in translation can be done using a rail, a slide or the like forming part of the structure 11.

The sensor 8 and drying 9 means are normally mounted fixed on said structure 11, but can also be provided to be mobile, like the print heads 6, to further increase the processing precision.

THE figures 4A and 4B illustrate two successive operating steps of a process for printing a surface 2' using an installation 1 according to the figure 1 and comprising printing means 5 according to the figures 3A to 3C .

In the first step ( figure 4A ), the print head 6, 7 assigned to the color cyan is positioned by translation along the Y axis (horizontal direction) vertically and in the axis of the sensor means 8 and of the drying/cross-linking means 9 ( PSD position). The multi-axis robot arm 4 moves the part 2 in front of the said head 6, 7 which projects the cyan-colored ink onto the surface 2' to be printed according to a predefined printing program, executed by the calculation, management and control means 10 which also exploit the information provided by the sensor means 8 concerning the relative position and the displacement parameters of the part 2.

The drying/crosslinking means 9 ensure the fixing and at least partial solidification of the deposited drops.

Under the control of the means 10, the multiple head 5 in the form of a bar is then moved by one notch, by driving via a linear actuator (not shown), in such a way that the head 6, 7 assigned to the magenta color is found in the PSD position. Again, the ink is projected according to a predefined program while the part 2 moves in front of the active head 6, 7 (magenta head) and the drops are dried by the means 9. These steps are then repeated for the two other colors , to complete the print cycle.

Optionally, the whole of the printing cycle can be repeated with a very slight voluntary shift of the printheads 6, 7 (compared to their position during the previous printing cycle), in order to obtain an even higher resolution. better.

According to a second variant embodiment, illustrated in figure 5 , it can be provided that the printheads 6, 7 are arranged circularly around the second axis Z and are movable together in rotation around this axis Z, under the effect of a suitable rotary actuator (not shown) driven by means 10 of calculation, management and control.

Like the aforementioned variant, the printing process is carried out in successive stages by rotating the module grouping together the different heads 6 by a fraction of a turn (here a quarter turn) around the Z axis.

As before, the sensor and drying means 8 and 9 are normally fixed, but can be designed mobile concomitantly with the print heads 6.

In accordance with an additional characteristic with respect to the two aforementioned variants, and compatible with them, provision may be made for each of the print heads 6, 7 to also be movable individually, under the effect of a suitable controlled actuator (not shown) , specific to each head 6, 7 or common to all the heads 6, 7, sliding along the first axis X (not shown).

The result is greater flexibility in maneuver and application, as well as greater control, better control and greater flexibility in terms of throwing distance.

In accordance with a third constructive variant of the invention, shown in the figure 6 , the printheads 6, 7 can be arranged linearly side by side along the second axis Z and be, on the one hand, slidably movable together along this Z axis and, on the other hand, individually slidably movable along the first axis X, this under the effect of suitable translational actuators (not shown) controlled by the means 10 of calculation, management and control (for example an automaton), with which can be associated a console 10 'of control and programming.

The control sequence of the printheads 6, 7 advantageously comprises, successively, first a sliding along the Z axis for the selection of the color to be applied, then a sliding along the X axis to bring the ejection orifice 13 (nozzle) concerned near the surface to be decorated.

Finally, and as illustrated in the figure 7 , it can also be provided that the printheads 6, 7 are mounted on or in the support structure 11 with the ability to move slidably, individually, along the three axes X, Y and Z, under the effect of adequate translational actuators controlled by the means 10 of calculation, management and control.

A person skilled in the art understands that the vertical Z and horizontal XY orientations represented in the figures are only by way of the most common example. Indeed, and in accordance with a suitable construction and orientation of the device 4 for moving the part 2, these axes X, Y and Z can be inverted, the Z axis then no longer corresponding to the vertical direction (variant not shown ).

Advantageously, the support structure 11 is provided with a cowling 12 with an opening 12' materializing the determined spatial position authorizing PSD printing, this opening 12' authorizing, if necessary, the passage of a print head 6 , 7.

Furthermore, given the vertically superimposed arrangement of the means 5, 8 and 9, the support structure 11 with the cowling 12 advantageously has a columnar shape, simple and compact.

In accordance with a second embodiment of the installation 1, schematically illustrated in the figure 11 , the support structure 11 consists of a bay or a shelf for storing a printhead maintenance station 6, 7, and said installation 1 comprises a second displacement device 4' with at least five degrees of freedom, preferably a second six-axis robot arm, configured to selectively move a print head 6, 7 from its location in the bay or the storage shelf 11 to the determined spatial position PSD, and vice versa, this under the control of the means 10 calculation, management and control. Said printhead 6, 7 can be maintained at this position PSD during the progress of the printing or coating operation with this head 6, 7.

Advantageously, the second robot arm 4′ is equipped, at its free end, with an automatic tool loader 14, with its automatic piloting device, on which can be mounted, temporarily and interchangeably, the head 6, 7 selected for the intended printing operation, the management of the operation of each print head 6, 7 and of the ink circulation, in line with the possible movements of the robot arm 4' carrier being carried out by the means 10.

When it is not in use, each printhead 6, 7 is, in this second embodiment of the installation, stored in the support structure 11 (whose size and number of reception slots is adapted to the needs in qualitative and quantitative terms).

Each print head 6, 7 can be in ink recirculation or not, the management of the depressions is computerized (means 10) and adapts in real time to the movements of the robot 4 ', and to the orientations of the head 6, 7 concerned.

The mounting of each head 6, 7 on its automatic tool changer 14 allows any orientation of the mounted head to work in the entire sphere of action of the robot 4'.

To implement a printing color, the robot 4' takes the head 6, 7 of the corresponding color from the storage rack 11 thanks to the automatic tool changer 14.

The ink and printhead control parameters are advantageously adapted in real time to compensate for the movements of the wrist of the robot 4' when the head is set in motion at the end of the wrist of the robot.

• la tête mise en oeuvre est positionnée par le robot en tant que tête d'impression fixe (principe Impression Pièce Portée, la pièce sera déplacée devant la tête fixe par l'autre robot 4). La possibilité de faire varier la position de travail fixe pour morphologie de pièce à traiter permet de simplifier grandement la programmation des trajectoires du robot chargé de réaliser les trajectoires d'impression,
• la pièce 2 est portée par un premier robot 4, la tête d'impression est portée par un second robot 4' et les deux robots 4 et 4' travaillent en collaboration sous le contrôle des moyens 10. Cela ouvre la possibilité de traiter des pièces beaucoup plus volumineuses, et sur toutes leurs faces.

In the context of this second embodiment of the invention, those skilled in the art understand that each print head 6, 7 can be used in the following two configurations, namely:

• the head implemented is positioned by the robot as a fixed printing head (principle Printing Part Carried, the part will be moved in front of the fixed head by the other robot 4). The possibility of varying the fixed working position for the morphology of the part to be treated makes it possible to greatly simplify the programming of the trajectories of the robot responsible for carrying out the printing trajectories,
• the part 2 is carried by a first robot 4, the print head is carried by a second robot 4' and the two robots 4 and 4' work in collaboration under the control of the means 10. This opens up the possibility of processing parts much larger, and on all their faces.

Preferably, the different printheads 6, 7 all have similar constructions and external shapes.

According to a first embodiment, emerging from figures 3 to 7 , the installation 1 preferably comprises four monochromatic printing heads 6, each head 6 comprising at least two parallel rows of orifices 13 for ejecting ink of the same color (see in particular figures 8 and 9 ). When a very high print resolution is desired, each head 6 may alternatively comprise only one row of orifices 13 for a given color.

According to a second embodiment, shown partially in the figure 10 , the installation 1 can comprise two bi-chromatic printing heads 7, each head 7 being constituted by the assembly of two monochromatic heads 6 each comprising two rows of orifices 13 for ejecting ink of the same color.

The practical realization of the means 4, 4', 5, 8, 9 and 12, as well as the design of the control and printing programs, are within the reach of those skilled in the art, in particular automation specialists. and automated printing systems.

Advantageously, the installation 1 can exploit the instantaneous speeds of fractions of the surface 2' of the part 2 in displacement (acquired by the sensor means 8 and exploited by the means 10) to manage the printing cycle, as mentioned in the patent application French n° 18 54024 on behalf of the plaintiff, by way of illustrative example (cf. figure 2 notably).

Similarly, the drying/or crosslinking means 9 can advantageously comprise a radiation source with means for adjusting the beam as described and represented in the patent application French n° 17 50260 on behalf of the plaintiff, by way of illustrative example.

Of course, the invention is not limited to the embodiments described and shown in the appended drawings. Modifications remain possible, in particular from the point of view of the constitution of the various elements.

Claims (11)

1. Installation (1) for printing and/or coating surfaces of parts, in particular three-dimensional surfaces, this installation (1) essentially comprising:

   - a part support (3), capable of receiving and holding a part (2) to be decorated or to be coated and mounted on a displacement device (4) with at least five degrees of freedom, such as, for example, a six-axis robot arm,

   - inkjet or similar printing means (5), consisting of at least one print head (6 or 7),

   - sensor means (8), capable of measuring parameters of positioning and/or of displacement of the part (2), in particular displacement speeds and/or positioning coordinates,

   - possibly, means (9) for drying and/or cross-linking, at least partially, substances sprayed onto the surface (2') of the part (2) to be decorated,

   - computation, management and control means (10) able and intended to make use of the signals delivered by the sensor means (8) and to control at least the printing means (7) and the displacement device (4),

   the printing means (7), the sensor means (8) and the possible drying means (9) being arranged side-by-side, superposed, on a fixed support structure (11), such as a plinth, an upright, a gantry or the like,

   the displacement device (4) and the support structure (11) being disposed mutually facing one another and a spatial reference frame (X, Y, Z) being assigned to said fixed support structure (11), with a first axis (X) determining the distance between the displacement device (4) and said support structure (11), a second axis (Z) corresponding to the direction of stacking of the printing, sensor and possibly drying means (5, 8, 9) and a third axis (Y) at right angles to the two preceding axes (X and Z),

   wherein the printing means (5) consist of at least two monochromatic (6) or bichromatic (7) print heads that are movable, in rotation and/or in translation, with at least one degree of freedom, said heads (6, 7) being able to be displaced selectively, one by one, to a determined spatial position (PSD) allowing the printing of the surface (2') of the part (2), this being done under the control of the computation, management and control means (10), and in accordance with preprogrammed data, for example a printing program, determining also the displacement of the part (2) relative to the support structure (11) and to the determined spatial position (PSD).
2. Installation according to Claim 1, characterized in that the print heads (6, 7) are arranged side-by-side linearly on the third axis (Y) and are movable together by sliding on this axis (Y) , this being done under the effect of a suitable translational actuator driven by the computation, management and control means (10).
3. Installation according to Claim 1, characterized in that the print heads (6, 7) are arranged circularly around the second axis (Z) and are movable together in rotation about this axis (Z), this being done under the effect of a suitable rotary actuator driven by the computation, management and control means (10).
4. Installation according to either one of Claims 2 and 3, characterized in that each of the print heads (6, 7) is also movable individually, under the effect of a suitable driven actuator, specific to each head (6, 7) or common to all the heads (6, 7), by sliding on the first axis (X).
5. Installation according to Claim 1, characterized in that the print heads (6, 7) are arranged side-by-side linearly on the second axis (Z) and are, on the one hand, movable together by sliding on this axis (Z) and, on the other hand, movable individually by sliding on the first axis (X), this being done under the effect of suitable translational actuators driven by the computation, management and control means (10).
6. Installation according to Claim 1, characterized in that the print heads (6, 7) are mounted on or in the support structure (11) with the facility for displacement by sliding, individually, on the three axes (X, Y and Z), this being done under the effect of suitable translational actuators driven by the computation, management and control means (10).
7. Installation according to any one of Claims 1 to 6, characterized in that the support structure (11) is provided with a hood (12) with an aperture (12') embodying the determined spatial position allowing the printing (PSD), this aperture (12') if necessary allowing the passage of a print head (6, 7).
8. Installation according to Claim 1, characterized in that the support structure (11) consists of a rack or storage shelving of a maintenance station of the print heads (6, 7), and in that said installation (1) comprises a second displacement device (4') with at least five degrees of freedom preferentially a second six-axis robot arm, configured to selectively displace a print head (6, 7) from its location in the rack or the storage shelving (11) to the determined spatial position (PSD), and vice versa, this being done under the control of the computation, management and control means (10), said print head (6, 7) being held in this position (PSD) while the operation of printing or coating with this head (6, 7) proceeds.
9. Installation according to Claim 8, characterized in that the second robot arm (4') is equipped, at its free end, with an automatic tool loader (14), with its automatic driver device, on which can be mounted, temporarily and interchangeably, the print head (6, 7) selected for the planned printing operation, the management of the operation of each print head (6, 7) and of the circulation of ink, appropriate to the possible movements of the bearing robot arm (4') being performed by the means (10).
10. Installation according to any one of Claims 1 to 9, characterized in that it comprises four monochromatic print heads (6), each head (6) comprising at least two parallel rows of orifices (13) for ejecting ink of the same colour.
11. Installation according to any one of Claims 1 to 9, characterized in that it comprises two bichromatic print heads (7), each head (7) consisting of the assembly of two monochromatic heads (6) each comprising two rows of orifices (13) for ejecting ink of the same colour.

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