Ink-jet printing module for printing robot, magazine for these modules, and ink-jet printing method using this robot

Abstract

To provide an inkjet printing system which can easily be manipulated by a robot arm having a plurality of axes.SOLUTION: An inkjet printing module 1 is capable of being picked up by an arm 111 of a robot. The module includes: a print head 2; an ink reservoir 3 capable of supplying ink to the print head; compressed-gas supply means 4 capable of supplying compressed gas to the print head; a mechanical interface 7 capable of engaging removably with a complementary mechanical interface 107 of the robot arm; an electronic interface 6 capable of engaging removably with an electronic interface 106 of the robot arm in order to transfer data between the module and the robot; and at least one fluid interface 5 placed in fluid communication with the compressed-gas supply means or with the ink reservoir.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to the field of inkjet printing technology for depositing inks or varnishes on surfaces of industrial parts, in particular on non-flat surfaces. Typically, the purpose of this printing is to decorate, protect or functionalize the industrial parts. More specifically, the present invention relates to a device and a method for inkjet printing on the surfaces of decimeter or meter-sized industrial parts using a multi-axis robot.

[0002] Prior Art The stylish decoration of visible surfaces is becoming increasingly important in many sectors, especially in the automotive sector. Nowadays, consumers can choose from a wide range of technical and aesthetic options to more individually design their cars. This concerns in particular the decoration of visible surfaces inside the vehicle cabin.

[0003] To accommodate this trend for customization, specialized vinyl inks and robotic digital printers have been developed that can print on curved surfaces, moldings, or parts, especially for decoration of dashboards, door panels, and other parts made of molded PVC for automobile interiors. This positioning printing technology makes it possible to print precisely and in color on any type of substrate for that customization.

[0004] Movable functional blocks provided with inkjet printheads are already known. These blocks can be attached to a robot arm, in particular according to the teachings of DE10 / 2017 / 202195 (Heidelberger Druck-maschinen), EP3290166 (Boeing) and EP2887011 (Hexagon Technology Center). In these configurations, the inkjet printhead is fed directly by a flexible hose. Similarly, EP2644392 (Heidelberger Druckmaschinen) describes an inkjet printhead block capable of printing on curved surfaces and fed by a data connection and ink supply hose.

[0005] However, these known solutions have undoubted drawbacks.

[0006] Many supply means must be used to connect the robot and the print head. These supply means, especially the fluid supply hoses and the power cables, can impede the movement of the robot. In addition, data transmission to the print head may require data lines. In any case, the presence of these supply means and electronic connection means involves additional assembly and maintenance time when replacing the print head. WO2013 / 158310 (Kateeva Inc.) describes a unit including multiple inkjet print heads mounted on a gantry that moves the heads in two main orthogonal directions on a planar table. This system may be suitable for printing on a flat surface, but is very complex.

[0007] In view of the above, the present invention aims to remedy at least some of the above-mentioned drawbacks of the prior art, in particular to provide an inkjet printing system that can be easily operated by a robotic arm having multiple axes, allows accurate printing on curved surfaces of industrial parts with dimensions that can exceed one meter, and allows decoration using multiple inks.

[0008] Subject of the Invention According to the invention, at least one of the above objects is achieved by an inkjet printing module that can be picked up by a robot arm via a quick coupling mechanical interface, said module comprising: A print head; - an ink reservoir capable of supplying ink to said print head; - compressed gas supply means capable of supplying compressed gas to said print head; - a mechanical interface removably engageable with a complementary mechanical interface of a robot arm; - an electronic interface removably engageable with an electronic interface of said robot arm for transferring data between said module and the robot; at least one fluid interface arranged in fluid communication with an ink reservoir and / or a compressed gas supply means.

[0009] The present invention first relates to this module.

[0010] Said compressed gas supply means may comprise an internal compressed gas reservoir integrated in said printing module, or may be an internal compressed gas reservoir, or may be represented by a connecting pipe between the print head and a fluid interface, said fluid interface being connected to an external compressed gas source when said printing module is in the printing configuration.

[0011] A printing module according to the invention may include an electronic interface and control lines extending between each of the printheads and ink reservoirs. Another optional control line may extend between the fluid interface and a compressed gas supply.

[0012] A printing module according to the invention may include a fluid interface and / or one or two connecting pipes extending between the ink reservoir and the compressed gas supply means, respectively.

[0013] The presence of the mechanical interface on said module facilitates its rapid connection with a complementary mechanical interface on the robot that can engage with the mechanical interface of the module. The presence of the ink reservoir makes the inkjet printing module self-contained for a certain period of time.

[0014] The present invention also relates to a robot for inkjet printing, comprising a robot arm, said robot arm comprising: - a complementary quick coupling mechanical interface engageable with the quick coupling mechanical interface of an inkjet printing module according to the invention; a complementary electronic interface engageable with the electronic interface of an inkjet printing module according to the invention.

[0015] The robot according to the invention may in particular be a 5- or 6-axis robot. It may comprise a central processing unit and at least one control line connecting this central processing unit with a complementary electronic interface.

[0016] The invention also relates to a magazine for inkjet printing modules capable of accommodating a plurality of inkjet printing modules according to the invention docked thereon, said magazine comprising: - a plurality of docking stations for inkjet printing modules, each docking station comprising at least one complementary fluidic interface engageable with a fluidic interface of an inkjet printing module according to the invention for transferring ink between the head and the docking station and / or for supplying compressed gas to the head; at least one complementary mechanical interface engageable with a mechanical interface of an inkjet printing module according to the invention;

[0017] The magazine may include at least one compressed gas source, which may be a compressed gas tank.

[0018] It may include at least one ink tank.

[0019] The magazine can replenish the inkjet printing modules with ink and compressed air, facilitating the use of multiple modules with different properties and ink colors to decorate the same part or set of parts.

[0020] The magazine according to the present invention comprises: - Each docking station is equipped with a specific ink tank, - the aforementioned ink tanks are filled with various types of ink or varnish, each station further comprises at least one complementary electronic interface engageable with an electronic interface of an inkjet printing module according to the invention, each station includes a compressed gas source, which may in particular be a compressed gas reservoir or a hose connected to an external compressed gas source, - each station includes a frame housing said at least one ink tank and / or said at least one compressed gas tank; the magazine comprises a movable assembly provided with said complementary mechanical interface, optionally with said complementary fluidic interface and / or with said complementary electronic interface, - said movable assembly comprises a carriage movable in a first direction, in particular horizontally, relative to the frame, and a connection block movable in a second direction, in particular vertically, relative to the carriage, said connection block being provided with said complementary mechanical interface and, if necessary, with said complementary fluidic interface and / or said complementary electronic interface; and - each station further includes a fixation flange extending from the frame (310), said flange and frame defining a volume for receiving the module, and means are provided for fixing said module to said flange and / or frame. All or some of these features may be included as long as they are technically compatible.

[0021] The invention also relates to an inkjet printing assembly comprising a robot according to any of the embodiments of the invention, a magazine according to any of the embodiments of the invention and at least one module according to any of the embodiments of the invention. Advantageously, the mechanical interface and the complementary mechanical interface define a detachable quick coupling, in particular of the right-angle hook type.

[0022] Finally, the present invention provides an inkjet printing method comprising the steps of: (i) picking up said inkjet printing module located in a docking station of a magazine capable of accommodating a plurality of modules, said picking being effected by engagement means between said complementary mechanical interface of the robot and said mechanical interface of said module; (ii) connecting a complementary electronic interface of said robot to an electronic interface of said module; (iii) moving the robotic arm to a printing surface; and (iv) printing ink on said surface by moving a robotic arm in one or more passes, said module being controlled by data transmitted to said module via said electronic interface and said complementary electronic interface; (v) at the end of the printing sequence, moving the robotic arm to a docking station; (vi) placing the print head in said docking station to isolate said electronic and mechanical interfaces.

[0023] The aforementioned method is (vii) moving the robotic arm to another docking station; (viii) performing steps (i) through (vi) using another inkjet print head located at the docking station.

[0024] The magazine described above may be a magazine according to the invention.The robot described above may be a robot according to the invention.

[0025] The term "ink" as used herein encompasses varnishes, such as clear varnishes, semi-transparent varnishes, pigmented varnishes, protective varnishes (scratch-resistant, abrasion-resistant, UV-resistant, etc.).

[0026] The method according to the invention comprises the steps of: - said ink reservoir of a module is refilled with ink by connecting a fluidic interface of said module with a complementary fluidic interface of said station; - the ink printing step (iv) is carried out using a first module while at least one other module is being replenished; and - Different modules are refilled using different types of ink or varnish, so long as the technical feature is technically compatible with the other processes, the process may include at least one of these technical features.

[0027] Finally, the invention relates to the use of the method according to the invention for printing on a surface curved in at least one main direction, said curved surface being the visible surface of a trim part of the passenger compartment of a motor vehicle. [Brief description of the drawings]

[0028] Other advantages of the invention will become apparent on reading the description of two embodiments of the invention given below, purely by way of example and not by way of limitation, with reference to the attached drawings, in which:

[0029] [Figure 1] Figure 1(b) shows an alternative embodiment of Figure 1(a), which differs only in the absence of a compressed gas reservoir, according to the present invention, in an inkjet printing module belonging to an inkjet printing assembly. [Diagram 2] FIG. 2 is a schematic diagram showing more specifically a robot that can engage with the module of FIG. 1 and that also belongs to the printing assembly of FIG. 1. [Diagram 3] 2 is a perspective view of a station engageable with the module of FIG. 1, the station belonging to a magazine engageable with a plurality of similar modules; [Figure 4] 1A-1C are schematic diagrams illustrating different stages of use of the printing assembly shown in the previous figure; [Diagram 5] 1A-1C are schematic diagrams illustrating different stages of use of the printing assembly shown in the previous figure; [Figure 6] 1A-1C are schematic diagrams illustrating different stages of use of the printing assembly shown in the previous figure; [Figure 7] 1A-1C are schematic diagrams illustrating different stages of use of the printing assembly shown in the previous figure; [Figure 8] FIG. 4 is a schematic diagram showing more precisely the engagement between the fluidic, mechanical and electronic interfaces of the module and the station of FIG. 3. [Figure 9] FIG. 4 is a top view showing more specifically the different interfaces of the module of FIG. 3; [Figure 10] FIG. 4 is a side view showing more specifically the different interfaces of the station of FIG. 3; [Figure 11] FIG. 1 is a schematic diagram of an inkjet printing assembly including an inkjet module mounted on a five-axis robot in accordance with the present invention. [Figure 12]Figure 12(a) is a photograph showing an automobile cabin trim section decorated with a printing method according to the present invention, and Figure 12(b) shows an enlarged view of the area shown in Figure 12(a).

[0030] The following reference numbers are used in the drawings: [Table 1] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] The term "ink" is herein interpreted in its broadest sense, particularly in relation to inkjet printing techniques known to those skilled in the art, and includes any kind of varnish, whether pigmented or unpigmented, transparent or opaque, including also protective varnishes.

[0032] As shown in FIGS. 1-4, an inkjet printing assembly in accordance with the present invention essentially comprises: - at least one printing module. In the example shown, six printing modules are provided, designated by the references 1A to 1F, a robot, generally designated by the reference numeral 101, It will be understood that the magazines generally designated by reference number 201, in particular for fixing the aforementioned modules as well as for emptying and refilling them with fluids, may be provided in a number different from that of the printing modules.

[0033] First, the structure of one of the printing modules 1A will be described, it being understood that the other modules have an identical structure. With reference to Fig. 1(a), this module comprises a housing 10 made of any suitable material, for example steel or plastic material. This housing has, for example, a parallelepiped shape and houses the various functional elements of the module.

[0034] Firstly, there is a print head, generally designated by the reference number 2. This print head is of a type known per se and is in particular provided with spray nozzles (not shown in the drawings) for spraying ink on a work surface. According to the invention, the head 2 is firstly placed in communication with an ink reservoir 3, via a channel 31. This is also placed in communication with a compressed gas source, via a particular channel 41. Said compressed gas source can be a compressed air reservoir 4, as in FIG. 1(a). These two reservoirs 3 and 4 are also placed in communication with a fluidic interface 5, the function of which will be described in more detail below. 51 and 52 represent this interface and the respective channels fluidically connecting these reservoirs.

[0035] 1(b), the compressed gas reservoir is omitted and the fluid interface 5 is fed by an external compressed gas source, as described below. In this case, the duct 52 communicates with the print head 2, possibly directly, via a control element (not shown).

[0036] The printing module according to the invention is further provided with an electronic interface 6, the function of which will be described in more detail below. Control lines 60, 61 and 62 connect this interface 60 to the print head 2 and to the reservoir 3 and reservoir 4, respectively. Finally, the module is provided with a mechanical interface 7, the function of which will be discussed in more detail below.

[0037] In an alternative embodiment (not shown in the drawings), the ink reservoir 3 is removable and can be replaced when it is emptied, in which case the ink supply means of the ink reservoir, in particular the channel 51 connecting the ink reservoir with the fluidic interface 5, may be omitted. In yet another alternative embodiment (not shown in the drawings), the ink reservoir and the printhead form a single entity that is removable and can be replaced when it is emptied, and as in the previous alternative, the ink supply means of the container may then be omitted.

[0038] The structure of the robot 101 will now be described in more detail with reference to Figure 2. Said robot comprises a body 110 forming a base of any suitable type and a gripper arm 111. The body 110 is optionally provided with at least one additional arm so that the gripper arm can move in several spatial directions. Typically, the robot 101 is of the six-axis type and these robots are known as such.

[0039] The arm 111 is provided near its free end with a mechanical interface, called complementary mechanical interface 107. Said interface is engageable with the mechanical interface 7 provided on the module 1. These two mechanical interfaces are of a type known per se and in particular allow a removable fixation between the module and the robot. By way of non-limiting example, these two interfaces in particular define a quick coupling, typically of the right-angle type. These quick coupling mechanical interfaces, or mechanical couplings, are well known to those skilled in the art and are described, for example, in the ISO 11593 standard. In the context of the present invention, the presence of such an interface is essential, but its structure is not critical. For example, the robot tool change system of the MPS series sold by the company Staubli can be used.

[0040] The arm 111 is also provided near its free end with a complementary fluid interface 108 that is engageable with the fluid interface 5 of the module 1. Said complementary fluid interface 108 is connected to an external compressed gas source, which is typically a flexible tube 140 that extends along the arm 111 of the robot 101. This complementary fluid interface 108 is only necessary if the module 1 does not have a compressed gas reservoir and requires an external compressed gas source. These quick coupling fluid interfaces, or fluid couplings, are well known to those skilled in the art and their structure is not critical.

[0041] The robot is also provided with a central processing unit, shown diagrammatically and generally designated by the reference numeral 161. This central processing unit is connected via a control line 160 to an electronic interface, called complementary electronic interface 106, which is engageable with the electronic interface 6 of the module 1. These two electronic interfaces (or couplings) are of a type known per se and make it possible to transfer data from the unit 161 to the print head 2, these data may be represented by analogue and / or digital signals.

[0042] It is therefore easy to see that the mechanical interface 7 of the module 1 is a coupling, preferably a quick coupling coupling, designed to be engageable with the complementary mechanical interface 107 of the arm 111 of the robot 101, and the fluidic interface 5 of the module 1 is a coupling, preferably a quick coupling coupling, designed to be engageable with the complementary fluidic interface 108 of the arm 111 of the robot 101. Similarly, the electronic interface 6 of the module 1 is a coupling designed to be engageable with the complementary electronic interface 106 of the arm 111 of the robot 101. When the two fluidic interfaces 5, 108 are coupled, they allow the passage of a fluid. In contrast, when these two interfaces are separated, each of the aforementioned interfaces seals a particular fluid against the outside air.

[0043] Figure 4 shows this coupling diagrammatically between two electrical interfaces 106 and 6 and between two mechanical interfaces 107 and 7, in this example where the module 1 has a compressed gas tank 4 and there is no need to connect the fluid interface 5 to a complementary interface on the robot arm 111. An example of the structure of these different interfaces is given below in connection with Figure 9.

[0044] The structure of the magazine 201 will now be described in more detail with reference to FIG. As shown in this figure 3, this magazine comprises a certain number of stations 301 for engaging with the modules 1 mentioned above. Preferably, there are as many stations 301 as there are modules 1, i.e. in other words, each station is dedicated to a certain module. However, in alternative embodiments, a different number of stations and modules may be provided. In this context, a given module may be engageable with multiple stations and / or a given station may be engageable with multiple modules. In this figure 3, a single station 301 is shown in detail, while stations 301' and 301'', located immediately on either side of station 301, are only very diagrammatically shown by dashed double-dashed lines.

[0045] The structure of one of the stations will now be described, with the understanding that the other stations generally have an identical structure. With reference to Figure 3, this station 301 firstly comprises a frame 310, substantially of parallelepiped shape, which houses various functional elements described below. A platform or flange 309 for fixing a particular module projects forward from one of the sides of the frame previously described. As shown in Figure 3, the adjacent walls of the frame and of the flange define a volume, represented by V1, for receiving a particular module 1.

[0046] This flange is provided with mechanical means for holding the aforementioned module in place when it is fixed. More precisely, this flange 309 is provided with an upper edge 370 and a lower edge 371, for example, for centering the module when it enters its receiving volume V1. Furthermore, the upper edge 370 is provided with a pin 372 for fixing the module relative to the flange. To this end, this module is provided with an opening (not shown) for engaging the previously mentioned pin, for example by means of an elastic snap fit.

[0047] As shown in Figure 8, several tanks for receiving different fluids are housed in the frame. There are tanks called ink tank 303, compressed air tank 304 and a purge tank 308 for receiving used ink. The ink tank 303 and the purge tank 308 may be omitted if the module 1 uses an ink reservoir that is replaced when empty. Finally, the station 301 is provided with a central processing unit 360 capable of controlling in particular the operation of the various interfaces of the station, which will be described below.

[0048] Furthermore, the station 301 is provided with a movable connection assembly, generally designated by the reference numeral 320. This assembly 320 firstly comprises a carriage 321 movable in the YY direction relative to the frame 310. To this end, the upper wall of the frame is provided, for example, with a rail 322 which engages with a sliding channel (not shown) provided on the carriage. The carriage is moved along these rails by any suitable type of motor means (not shown).

[0049] The carriage 321 supports a pillar 324 fixed relative to it and positioned in front of said carriage, specifically facing the storage volume of the module, which in turn supports a connection block 326 movable in the ZZ direction relative to it. To this end, for example, a jack 328 is provided, the body of which is rigidly connected to the pillar and the rod of which is rigidly connected to the block.

[0050] The connection block 326 is provided with several interfaces. Firstly, there is a fluid interface 305 designed to be able to engage with the fluid interface 5 of the module 1. These two fluid interfaces are of a type known per se and allow a quick-coupling detachable connection to be established between the module 1 and the station 301. When these two interfaces are joined, said connection allows the passage of a fluid between this module and this station. In contrast, when these two interfaces are separated, each of said interfaces seals a particular fluid against the outside air.

[0051] The interface 305 is connected to the reservoirs 303 (if present) and 304 by respective channels 331 and 341 (see FIG. 8 ). Furthermore, an additional connecting channel 381 may be provided connecting the print head 2 and the purge tank 308. This channel 381, which may be removably coupled to this print head, is associated with a vacuum source (not shown).

[0052] The connection block 326 is also provided with two additional interfaces, respectively an electronic interface 306 and a mechanical interface 307. These interfaces 306 and 307 are similar to the above-mentioned interfaces 106 and 107 provided on the robot arm 111. The electronic interface 306 is connected via a control line 361 to a central processing unit 360 (see FIG. 8).

[0053] 9 and 10 show, by way of example, one possible embodiment of the various interfaces provided on the modules and stations respectively.

[0054] As shown in Fig. 9, the fluid interface 5 of the module is formed by two female coupling elements 5' and 5'' for the circulation of compressed gas and ink, respectively. Furthermore, as shown in Fig. 10, the fluid interface 305 of the station is formed by two male coupling elements 305' and 305'' for engaging with the coupling elements 5' and 5''.

[0055] In addition, the electronic interface 6 of the module is formed by a female connector element, as shown in Fig. 9. Furthermore, the electronic interface 306 of the station is formed by a male connector element for engaging with the female connector 6, as shown in Fig. 10.

[0056] Finally, the mechanical interface 7 of the module is formed by a female quick coupling, as shown in Fig. 9. Furthermore, the mechanical interface 307 of the station is formed by a male connector element for engaging with the female quick coupling 7, as shown in Fig. 10.

[0057] It should be noted that the structure of the electronic interface 106 and the mechanical interface 107 provided on the robot are not described in more detail. Typically, these interfaces are similar to the interfaces 306 and 307 provided on the station, as described with reference to FIG.

[0058] Use of the printing assembly described above will now be described with reference to Figures 4 to 8.

[0059] First, with reference to Fig. 4, it is assumed that the containers 3 and 4 are filled with ink and compressed air, respectively. Two interface pairs 6 and 106, and 7 and 107, respectively, are engaged. As a result, the robot and the module are electronically connected, in particular the central processing unit 161 can control the various components of the module via lines 160, 60, 61 and 62, indicated by the arrow f. Furthermore, the robot and the module are mechanically rigidly connected to each other by the interfaces 7 and 107.

[0060] Thus, the robot controls the print head 2 to spray ink onto the target surface, as indicated by arrow p. During this spraying process, additional ink and air are pumped into the head 2 from the reservoirs 3 and 4, as indicated by arrow F. During this printing operation, the station 301 is not engaged with the module 1, i.e., the storage volume V1 is empty, as shown in FIG.

[0061] At the end of this printing operation, container 3 and container 4 are empty. At this point, said containers need to be refilled, as shown in figures 5 to 8. The arm 111 first guides the module 1 into the storage volume so as to dock it on the flange 309. The module is fixed to this flange, in particular by means of the pin 372. The interfaces 7 and 107 are then separated so that the arm can be withdrawn.

[0062] As can be seen in Fig. 5, when docking the module to the flange, the mobile assembly is in what is called the deactivation position, i.e. the connection block cannot engage with the module. This mobile assembly is then moved in two successive steps. The first step is to move the carriage horizontally towards the storage area in the direction of the arrow F321. At this point, the connection block 326 is located directly above the module while being spaced away from it, as shown in Fig. 6.

[0063] This block is then moved vertically downwards in the direction of arrow F326 to engage the connection block with the module. In this operating position of the moveable assembly shown in Figure 7, there is mutual engagement between mechanical interface 7 and mechanical interface 307, between fluidic interface 5 and fluidic interface 305, and between electronic interface 6 and electronic interface 306.

[0064] As shown in FIG. 8, which shows only the frame 310, the block 326 and the module 1, the central processing unit 360 thus controls the filling of the reservoirs 3 and 4 from the respective tanks 303 and 304, indicated by the arrows G. In addition, a purge line 381 is coupled to the print head 2. A washing solvent is injected into the internal volume of the head from a solvent reservoir (not shown). The used ink initially present in the head is sucked out of the head so as to be discharged into the reservoir 308 in the direction of the arrow g. This purging action prevents the print head 1 from becoming clogged with dried ink during its inoperative periods.

[0065] Module 1 is again operational, ready for additional printing operations to be performed in a similar manner as described above. It should be noted that while replenishing module 1, robot 101 can pick up another module to perform another printing operation. Thus, the printing assembly according to the present invention can perform one operation in parallel with another operation.

[0066] Advantageously, the tanks 303 belonging to the different stations are filled with different types of ink, each tank intended to feed a dedicated print head for spraying a particular ink on a target surface. In the sense of the present invention, different types of ink may mean that the inks have different colors and / or different physicochemical properties (such as viscosity or density) and / or different appearances (such as gloss).

[0067] In the described and illustrated example, each station is provided with a compressed gas tank. However, in an alternative embodiment, the entire magazine can be provided with a single compressed gas tank with a larger volume. In this case, this single tank is connected to the fluid interfaces of each station via specific pipes. It is also possible that neither the stations nor the magazine contain an air tank, and the compressed gas supply is from an external line connected to the magazine.

[0068] The present invention has many advantages: Due to the self-contained nature of the ink (and possibly compressed gas) printing module 1, the movement of the robot 101 according to the present invention is not hindered by the presence of flexible tubes and cables, which simplifies the design, programming and use of the robot.

[0069] The robot 101 according to the invention can be used to inkjet deposit protective inks and / or varnishes on the surfaces of three-dimensional parts. These surfaces can have decimeter or meter dimensions and therefore their maximum dimensions can be, for example, about 2 dm to about 2 m. These surfaces can be curved and can also include, for example, millimeter-scale surface structures.

[0070] By way of example, the robot can be used to decorate trim parts of the passenger compartment of an automobile. These trim parts can be, for example, trim parts of the dashboard or the doors, and their maximum dimensions can typically be between 3 dm and 1.5 m. These parts can be manufactured according to known methods, such as, for example, by forming a PVC coating with a decorative surface appearance on a substrate (core), such a method being described in WO 98 / 00277 (Elf Atochem SA). These parts can have pseudo seams, the surface of which usually presents details of about 0.1 mm to about 20 mm in size. The robot according to the invention makes it possible to decorate these details by inkjet.

[0071] Figure 11 shows diagrammatically an inkjet printing assembly according to the invention, including an inkjet printing module 1 mounted on a five-axis robot 101, the axes being represented by the references A1-A5. The printing module 1 is moved over the surface to be decorated of a to-be-decorated part 400, in this case the surface is curved and the decoration includes a line 401 which may or may not be straight, continuous or discontinuous, and which may or may not be on a ridge of the curved surface. As shown in Figure 12, the line may be raised and / or include a raised decoration.

[0072] Fig. 12 shows a photograph of a portion of the surface of a part to be decorated 400, in this case a trim part of the passenger compartment of a motor vehicle. This surface comprises an "artificial leather" grain. It comprises artificial seams arranged along two lines 401a, 401b which include raised decorative elements 402. The method according to the invention in particular makes it possible to deposit ink of the desired color on these raised decorative elements, excluding the surrounding areas, in other words the ink covers only these raised decorative elements. The positioning accuracy of the ink on these raised decorative elements is possible down to 0.10 mm, using ink drops with a diameter of about 80 μm.

[0073] The ink can be deposited in one or more passes. The inkjet decoration can be completed by depositing a transparent varnish, also in an inkjet manner. Since the magazine for inkjet printing modules according to the invention can comprise a number of inkjet printing modules, each with a different ink, it is easy to deposit a transparent varnish after decoration by jetting ink of the desired color, which can be done by exchanging a module with an ink for another module with a varnish. It is likewise easy to use a different ink for the next part to be decorated. Thus, the invention gives the manufacturer of decorated parts a high degree of flexibility and answers customer demands for customizing objects.

Claims

1. An inkjet printing module (1) that can be picked up by an arm (111) of a robot (101) via a quick coupling mechanical interface, said module comprising: a print head (2), an ink reservoir (3) capable of supplying ink to said print head (2); compressed gas supply means (4) capable of supplying compressed gas to said print head (2); a quick coupling mechanical interface (7) releasably engageable with a quick coupling complementary mechanical interface (107) of the robot arm; an electronic interface (6) removably engageable with an electronic interface (106) of the robot arm for transferring data between the module and the robot; at least one fluid interface (5) arranged in fluid communication with said compressed gas supply means and / or with said ink reservoir; A module comprising:

2. 2. A module according to claim 1, characterized in that the compressed gas supply means comprises a compressed gas reservoir integrated in the module (1).

3. A module according to claim 1 or 2, characterized in that the ink reservoir (3) comprises the compressed gas reservoir.

4. A module according to any one of claims 1 to 3, characterised in that it comprises one or two connecting pipes extending between said fluid interface (5) and / or said ink reservoir (3) and said compressed gas supply means, respectively.

5. An inkjet printing robot (100) comprising a robot arm (111), said robot arm comprising: - a quick-coupling complementary mechanical interface (107) engageable with the quick-coupling mechanical interface (7) of a module according to any one of claims 1 to 4; - a complementary electronic interface (106) engageable with the electronic interface (6) of a module according to any one of claims 1 to 4; A robot comprising:

6. 6. A robot according to claim 5, characterized in that it comprises a central processing unit (161) and at least one control line (161) connecting said central processing unit and said complementary electronic interface.

7. 7. A robot according to claim 5 or claim 6, characterized in that it is a five-axis robot or a six-axis robot.

8. 1. An inkjet printing method comprising: (i) picking up a module according to any one of claims 1 to 4, located in a docking station of a magazine capable of accommodating a plurality of said modules, said picking being performed by means of engagement between a quick-coupling complementary mechanical interface of the robot and a quick-coupling mechanical interface of the module; (ii) connecting a complementary electronic interface of the robot to an electronic interface of the module; (iii) moving the robot arm to a printing surface; (iv) printing ink on the surface by moving the robotic arm in one or more passes, the module being controlled by data transmitted to the module via the electronic interface and the complementary electronic interface; (v) at the end of the printing sequence, moving the robotic arm to a docking station; (vi) placing the print head in the docking station to isolate the electronic interface and the quick coupling mechanical interface; A method comprising:

9. (vii) moving the robotic arm to another docking station; (viii) performing steps (i) through (vi) using another inkjet print head located at the docking station; and The method of claim 8 further comprising:

10. Method according to either claim 8 or claim 9, characterized in that the robot is a robot according to any one of claims 5 to 7.

11. The method of any one of claims 8 to 10, further comprising refilling an ink reservoir of the module with ink by connecting a fluid interface of the module with a complementary fluid interface of the station.

12. The method of claim 11 , wherein the step of printing the ink is performed using a first module while at least one other module is being refilled.

13. The method of claim 12, wherein different modules are refilled using different types of ink.

14. The method according to any one of claims 8 to 12, wherein the method is used for printing on a surface which is curved in at least one main direction.

15. 15. The method of claim 14, wherein the curved surface is a visible surface of an automobile interior cladding.

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