Method for printing to a warped surface and machine for implementing same

Abstract

The invention relates to a method for inkjet printing on a region (20) of a structure (7) of warped surface using an articulated robot (3). The structure is rotatably mounted on a drum (2) that is motorised (6) on a frame (1) fastened to the ground. An effector (8) with a print head (80) is mounted at the end of the arm, the head (80) moving in a vertical plane (V). Topographic and viewing data (13) of the region (20) are transmitted to a supervisor (101) that generates, after receiving the data of the image to be printed from a central printing unit (100), the path of the head and divides the image into strips (50) that are corrected in order to compensate for print deformation on a warped surface. These data are transmitted to the central unit (100) with a view to printing the image in the region (20), using the region as sole reference frame.

Description

[0001] DESCRIPTION

[0002] TITLE: METHOD FOR PRINTING A LEFT-HANDED SURFACE AND IMPLEMENTATION MACHINE

[0003] TECHNICAL FIELD

[0004] The invention relates to a method of inkjet printing on a so-called warped or deformed surface, in particular a pseudo-cylindrical or pseudo-conical substrate, that is to say, any surface not developable in a tangent plane, for example, a barrel shape. In particular, the invention applies to printing technical markings and logos on aircraft nacelles. The invention also relates to a machine for implementing such a method.

[0005] The invention also applies in any field where markings, decorations or logos are applied to uneven surfaces: automotive, railway, maritime or building sectors.

[0006] Inkjet printing can be performed on a variety of substrates, such as glass, ceramic, plastic, or metal. Because this printing process is contactless, it can be carried out on flat surfaces or surfaces that can be adjusted in a tangent plane.

[0007] Inkjet technology involves projecting microdroplets of ink through the nozzles of a print head onto the surface of the printing medium. The inkjet commands, print head movements, and media movement are coordinated by a processing unit according to the desired pattern.

[0008] STATE OF THE ART

[0009] Traditionally, this process is carried out using compressed air spray guns and requires numerous resources: masking materials and stencils for each color, a drying tunnel for the entire platform, cleaning of the painting equipment, etc. This technique generates high product consumption because a large proportion of the paint sprayed by the gun is not absorbed by the surface being treated, necessitating the treatment of the wastewater. Furthermore, since the application is performed by operators, it is difficult to guarantee consistent results.

[0010] Inkjet printing offers several advantages over paint or adhesive application, including better precision and reproducibility of the pattern to be applied, reduced cycle time, simultaneous printing of all colors, reduced product consumption when needed, no single-use consumables, and consistent and measurable quality of result.

[0011] Solutions for inkjet printing on non-developable surfaces, such as curved or deformed surfaces like an aircraft nacelle, involve a machine moving on the ground in conjunction with a robotic arm equipped with the print head. Since such markings can be applied to any part of an aircraft (fuselage, nacelles, tail assembly, wings, cockpit), equipment mounted on a mobile ground-based structure is used to cover all aircraft components.

[0012] For example, US patent 11207896 describes the use of data from an internal robot positioning system—as well as data from a reference system including a stationary reference external to the robot—to calculate an estimate of the printhead's position, velocity, and acceleration relative to the surface. When the printhead moves along the surface during printing—that is, when the printhead is moved while ink is ejected from the printhead nozzles—the printhead positioning and nozzle activation are controlled based on this estimate.

[0013] Furthermore, the print head of document US 2015009254 contains a plurality of inkjet nozzles to eject ink to a distant location by supplying pressurized air to each ink reservoir. This head is mounted on a linear array so that it can perform a linear reciprocating motion. The linear rail is held by a multi-articulated robot arm, the position of which is controlled based on position information, and the drive of predetermined nozzles in the head is controlled in conjunction with this position information. STATEMENT OF THE INVENTION

[0014] Using equipment mounted on a mobile ground structure requires significant leverage, which makes it impossible to print ungainly surface aircraft parts, such as nacelles, with sufficient precision and accuracy. In particular, such ground-based installations do not guarantee consistency or fidelity in producing the same print on different aircraft, as the prints must be identical in geometry and color. Numerous rework operations are therefore necessary to compensate for this limitation. Specifically, US patent 2015009254 uses a printhead guide rail, which restricts printable areas to flat or cylindrical surfaces.

[0015] The present invention aims to avoid such reprints by providing a high-precision print that is reproducible and conforms in geometry and colorimetry to an original design.

[0016] To achieve this, the present invention proposes using the surface to be treated as the sole reference frame for independent moving components during inkjet printing, thus making their movements compatible with mounting the robot and the surface to be printed on the same fixed frame. It then became apparent that inkjet printing can be performed with high precision on irregular surfaces.

[0017] More specifically, the present invention relates to a method for printing images by inkjet onto a non-developable surface area, referred to as a warped or deformed area. This method comprises the following steps:

[0018] - to mount in rotation a structure presenting said zone on a motorized receiving axis by drive step and extending in a so-called horizontal plane parallel to a given ground;

[0019] - fixing to the ground a chassis incorporating the receiving axis of the structure, the chassis being designed and calculated by finite elements so as to eliminate the identified natural frequencies and its deformations;

[0020] - arrange an inkjet effector at the end of a robotic arm comprising a print head consisting of at least one line of nozzles, the arm being articulated so that the head moves in a vertical plane perpendicular to the ground and passing through the receiving axis, thus freeing itself from the weight of the drops;

[0021] - to carry out a survey of topographic data of the area to be printed in conjunction with visualization data of this area, and to transmit this data to a digital application for controlling the trajectory of the arm;

[0022] - determine the trajectory of the print head and the print tops by the trajectory control application from data of the image to be printed previously recorded and cut into strips according to the topographic and visualization data;

[0023] - modify the strips by the prior application of at least one correction parameter which compensates for an image distortion caused by printing on the left surface;

[0024] - adjust the step size of the motorization and the drive speed of the receiving axis according to the strips to be printed;

[0025] - transmit the trajectory data and print tops to a digital print control application, which reproduces by inkjet, after superimposing the trajectory of the print head and the area to be printed, the image on the area of ​​surface to be printed cut by successive modified strips, taking this area as the sole basic reference of the trajectory of the arm, the inkjet of the print head and the step-by-step drive rotation of the surface to be printed with return of the print head at each strip.

[0026] To compensate for image distortion caused by printing on a warped surface, the image to be printed is pre-distorted by applying a correction parameter that modifies each image strip by inversely distorting it. Alternatively, or in conjunction with the correction parameter, a strip edge masking correction function can be implemented to hide printing discontinuities at those edges.

[0027] Advantageously, rotating the structure to be printed limits the path followed by the inkjet nozzle. Moving the print head in a vertical plane reduces printing inaccuracies above the surface being treated, which serves as a reference. Furthermore, the speed and deceleration of the robot arm are adjusted at the start of each print section so that the printed edges of the sections are aligned.

[0028] Advantageously, an encoding wheel in contact with the surface to be treated can be mounted on the effector in order to control and adjust the speed of the effector.

[0029] According to advantageous implementation methods:

[0030] - in the case where the surface of the structure has a barrel shape the image deformation parameter causes a progressive approach of each strip from a central axis of the strip perpendicular to the axis of rotation to the ends, each strip and therefore the resulting image progressively shrinking towards the ends;

[0031] - the rotation of the area to be printed is adjusted so that the printing done by each strip fits together with that of the previous strip;

[0032] - the rotation of the area to be printed is set so that the print made by each strip adjusts to that of the previous strip by leaving a space of predetermined width, this space being then occupied by the migration of the ink;

[0033] - the rotation of the area to be printed is set so that the printing done for each strip adjusts to that of the previous strip with an overlap of predetermined width and a reduced printing density so that this overlap compensates for the decrease in density.

[0034] The invention also relates to a printing machine dedicated to an advantageous implementation of the printing process defined above. This machine comprises the rigid metal alloy chassis fixed to the floor and on which are also fixed a rotating drum, mounted on a shaft around the receiving axis of the structure, the foot of the inkjet printing robot, a control bay for this robot in connection with a robot trajectory control PLC, and a drum drive motor, the so-called warped or deformed structure to be printed being fixed on the rotating drum.

[0035] In addition, the machine includes the effector which, mounted at one end of the robot arm, integrates the print head, a UV lamp for ink polymerization, an effector position detection camera and a means of topographic surveying to track the arm's trajectory.

[0036] A platform mounted at the other end of the arm's base accommodates a set of ink tanks; a bundle of flexible tubes supplies ink between a set of ink tanks and the effector via ink circulation pumps.

[0037] The machine also includes a supervisor for controlling the trajectory of the arm, and therefore of the effector, in which the digital application for the trajectory of the arm is installed, the supervisor being in bilateral connection with a central unit which hosts the digital printing application.

[0038] Synchronization network cables connect the supervisor to the central unit, the motorization of the structure's receiving shaft, the PLC controlling the arm's trajectory motorization, the camera, the UV lamp, and by means of topographic surveys whose data is managed by the supervisor after receiving the image data to be reproduced extracted from the image file from the central unit.

[0039] Furthermore, the chassis is advantageously spot-welded or equivalent, so as to present a rigidity which allows the equipment components mounted on this chassis - robot and structure to be treated - to be free from any play, deformations or vibrations.

[0040] Based on preferred characteristics:

[0041] - the motorization consists of a geared motor;

[0042] - the structure is attached to the drum by discs;

[0043] - the ink supply tubes are housed in a sheath maintaining an ink fluidity temperature, for example with heating resistors;

[0044] - the effector delivers at least four colors and has aligned print nozzles;

[0045] - The print head has at least four nozzle lines to simplify the robot arm's path, with each nozzle line delivering a base color. PRESENTATION OF FIGURES

[0046] Other data, features and advantages of the present invention will become apparent from the following non-limited description, with reference to the accompanying figures which represent, respectively:

[0047] - Figure 1, an overall perspective view of an example of a printing machine according to the present invention;

[0048] - Figure 2, an overall front view of the machine in Figure 1;

[0049] - Figure 3, a more detailed perspective view of the robot equipped with the printing effector;

[0050] - Figure 4, a perspective view from the front of the effector of the machine from the previous views equipped with rangefinders and the camera;

[0051] - Figure 5, a rear perspective view of the effector of Figure 4 showing in particular the UV lamp;

[0052] - Figure 6, a bottom view of the effector showing the nozzle lines of the print head;

[0053] - Figure 7, a functional diagram of the main components of the machine according to the invention;

[0054] - Figure 8, a diagram of the physical connections between the components relating to printing according to the invention, and

[0055] - Figure 9, a diagram showing the pre-image processing in the case of printing on a barrel-type surface.

[0056] DETAILED DESCRIPTION

[0057] In the figures, identical reference symbols refer to the same element and to the corresponding passages in the description. In the illustrated example, the surface to be treated is that of a barrel-shaped aircraft nacelle made of staves.

[0058] The overall perspective view in Figure 1 and the front view in Figure 2 illustrate an example of a machine according to the invention comprising a rigid metal frame 1 fixed to the ground S by means of feet 1a, and on which are installed a rotating drum 2, a robot 3 and its bay 4, as well as an electrical cabinet 5 incorporating a programmable logic controller 51 (see below with reference to Figure 8). With reference to the perspective view in Figure 3, the robot 3 is shown in more detail with a printing end effector 8 at one end and a platform 81 at its other end, referred to as the base.

[0059] The chassis 1 is composed of welded, hollow metal beams 11 arranged in a cradle shape to support the drum 2 without deformation. The drum 2 is itself driven in rotation by a radially arranged geared motor 6. The chassis 1 also supports the robot 3, whose base 30 is also made of hollow beams 11, advantageously forming an integral part of the same chassis 1. This chassis 1 also positions the structure to be printed on a shaft X1 with axis X'X, an aircraft pod 7 in this example, and secures this pod 7 to the drum 2 via discs 21.

[0060] The robot 3 is equipped with an arm 31 articulated by electric motors (not visible) on 6 axes A1 to A6. At the end of the arm 31, the effector 8 has a four-color print head 80 and, attached to its base 30, a platform 81 on which are located the ink circulation pumps 9 and the associated reservoirs 91. In addition, a bundle of tubes 10 supplies ink between the reservoirs 91 and the print head 80. Network cables 33 and electrical connections 32 are installed between the cabinet 5 and the effector 8 along the arm 31.

[0061] The entire system is managed by a supervisor 101 incorporating a digital application for controlling the robot arm's trajectory around its axes. This supervisor 101 regulates the printing cycles by coordinating the movement of the arm 31 and the geared motor 6 via the synchronization network cables 33 (see Figure 8 below) in conjunction with a central processing unit 100. This central processing unit 100 integrates a digital application for controlling the printing process. Alternatively, transmission can be carried out using wave transmitters / receivers in a Wi-Fi or Bluetooth network. The processors of the supervisor 101 and the central processing unit 100 can be separate or integrated within a single digital entity EN1 (shown as a dashed line in Figure 2), and the applications can be grouped into a single, more powerful processor.

[0062] The robot arm 31 is controlled to move along a trajectory in space following a topographic survey of the surface area to be processed 20. In this example, this survey is carried out using a group of three rangefinders 12a, 12b, and 12c. This area 20 is surveyed point by point using this group of three rangefinders 12a, 12b, and 12c, and the position of the end effector 8 (see Figure 1) is monitored by a camera 13. These rangefinders and this camera are shown in more detail in Figures 4 and 5, respectively in front and rear perspective. Alternatively to the rangefinders, a scanner 15 mounted on an extension 82 of the end effector 8 can be used to perform a topographic surface survey. The scanner 15 and the extension 82 are shown as dashed lines in Figure 4.

[0063] Figures 3 and 4 also show the ink supply tubes 10, housed in a common temperature-protective sheath 10g. This protection can be achieved by heating elements (not visible) with their intensity adjusted to maintain a constant temperature. Alternatively, the sheath 10g can be made of a flexible, insulating plastic material, such as layers of polyethylene.

[0064] In the central unit 100, a print control application manages an image file of the marking or logo to be printed and transmits the image to be printed, extracted from the file, to the supervisor 101. The central unit 100 also allows calibration of the dimensions, color, and adjustment of an image correction parameter to create edge effects on each of the strips to be printed successively on the area 20 of the surface to be treated (see Figure 9 below).

[0065] The 50 strips have a width defined by the rotation pitch of the surface to be printed, driven by the geared motor 6 via the drum 2; the length is that of the image to be printed in this example. Alternatively, the strips can be cut in width and length by programming the central processing unit according to any local curvatures of the surface to be processed, curvatures detected by telemetry.

[0066] Furthermore, a UV lamp 14 (see Figure 5), mounted on the effector 8, polymerizes the ink successively deposited on the aforementioned area 20 during the trajectory of the robot arm 31. The machine's operation is controlled by the supervisor 101. This supervisor first performs, for the first strip, a trajectory simulation in space along the X'X axis of the platform 7, based on the topographic survey of the area to be treated 20. The ink jets from the print head 80 then extend in the vertical plane V (see Figure 2), above the area 20. The supervisor 101 then controls the movement of the robot arm 31 along the recorded trajectory corresponding to the strips of the image to be printed, retrieved from the central unit 100.

[0067] To do this, the central unit 100 retrieves the setpoint of the selected image via a calibration and image adaptation parameter file from a source file (see further in reference to figure 7).

[0068] During movement, the robot's trajectory, defined by the supervisor 101, is secured—for example, through collision avoidance—and, if necessary, recalculated based on information received from the rangefinders 12a, 12b, and 12c. A predefined distance is thus maintained between the nozzle tips and the surface to be treated (4 mm in this example), and this distance is also received from the camera 13 to manage the proximity of successive strips. In this example, a continuous alignment is maintained between two successive strips.

[0069] Printing begins as soon as the supervisor 101 locates – via topographic surveys – the start of the image file on the corresponding path. This moment marks the start of the first print run on the beginning of the path to be followed. Drying is carried out by the UV lamp 14 immediately after the ink is applied. Once this first section is printed, the print head 80 returns to its original position, and the nacelle 7 rotates simultaneously, according to a programmed sequence controlled by the supervisor 101 application, following an angular command determined based on a print width predetermined by an image segmentation performed and calibrated by the central unit 100.

[0070] The printing of the second strip is then initiated. In this example, this printing is performed seamlessly with the first strip by adjusting the position parameters of the print head 80 based on data previously provided by the telemetry to the supervisor 101. Depending on the ink drying time and the image file corrections provided to the supervisor 101 by the central unit 100, the use of these parameters allows control over the quality of the seam. By repeating this operation, printing on multiple strips can be achieved. T from the same image file.

[0071] The bottom view of the print head 8 in Figure 6 in the example of four lines 8a to 8d, each line having Bx nozzles which delivers the same color, namely the four basic colors - cyan, black, magenta and yellow.

[0072] Figure 7 shows the functional links between the main components of this example of a machine according to the invention, around the supervisor 101 and the central unit 100, which are linked bilaterally. The trajectory control application of the supervisor 101:

[0073] - receives position data of the area to be printed from the topography, provided in the example by the telemetry 12, visualization data of this area from the camera 13, as well as data of the image to be printed extracted from the image file from the central unit 100;

[0074] - cuts the image received from the central unit 100 into strips of equal length to that of the area and of equal width to one rotation step of the nacelle in the example, and then determines the trajectory of the print head according to the successive strips to be covered by the print head 80, as well as the times of triggering the print tops of the nozzles Bx (see figure 6) as a function of the position and the shape correction of each strip to be printed in the area 20 (see further on with reference to figure 9);

[0075] - activates the 6-axis motorization in rotation of the nacelle and the 6-axis motorization for trajectory tracking of the robot arm 31 via a PLC 51 (see below with reference to figure 8) in order to move the arm 31 according to the trajectory determined according to the data received;

[0076] - transmits to the central processing unit's print control application 100 the data on the end effector trajectory and the print trigger times, and

[0077] - controls the activation of the UV lamp 14 for a duration adapted to the polymerization and drying of the ink deposited on the area, depending on the pigmentation of this ink. Regarding the printing application of the central printing unit 100, this application provides image data to the supervisor 101 and controls the four-color print head 80, as well as the supply of ink to this print head via the tubes 10, according to the print timing provided by the supervisor after superimposing the print head trajectory and the area to be printed. This supply is controlled according to data from a preliminary correction process relating to the shape of the strips (see below with reference to Figure 9).

[0078] Printing is performed continuously, using the print area 20 as the sole reference frame for the trajectory of the arm 31, the inkjet of the print head 80, and the step-by-step rotation of the print surface, with the print head returning to its starting position after each strip. Each strip has a width and a length corresponding respectively to the amplitude and speed—equal to the number of steps per unit of time—of the drive step.

[0079] Figure 8 shows the physical connections between the main components. The supervisor 101 controls the trajectory of the end effector 8 and the UV lamp 14 via the PLC 51 integrated into the cabinet 5, using data from the camera 13, the rangefinders 12a, 12b, 12c, and the nacelle rotation via the robot bay 4, through the synchronization network cables 33 and the electrical network 32. The supervisor 101 coordinates the trajectory of the end effector 8 and the printing to be performed via the network cable 32, which controls the ink tanks 91. The ink reaches the end effector 8 via the tubes 10 integrated into the sheath 10g.

[0080] In addition, an analog / digital converter 40 converts the analog data provided by the rangefinders 12a, 12b, 12c into digital data transmitted to the supervisor 101. Furthermore, a distribution box 41 collects and sorts the control and reception information respectively emitted by or transmitted to the supervisor 101.

[0081] With reference to Figure 9, a diagram shows an example of image preprocessing for printing on a barrel-shaped surface, thus reproducing the "stave effect." The image stored in the central processing unit 100 is selected and processed at the supervisor 101 to determine the print head trajectory and the shape of the strips corrected for the stave effect.

[0082] In this example, the processing involves shrinking each strip 50 of the initially rectangular image at its ends by applying a correction parameter that produces a continuous image distortion. This application causes a progressive contraction from a central axis Y'Y of strip 50, perpendicular to the rotation axis X'X of the rotation shaft X1, to its ends E1 to E4.

[0083] Each strip, and therefore the image constructed from all 50 strips, is progressively shrunk towards its edges by a selection of active nozzles. This shrinking is achieved by activating all nozzles in the center of the strip and progressively deactivating an increasing number of nozzles towards its edges. The print commands corresponding to the successive activation of the Bx nozzles (see Figure 6) selected by the supervisor 101 are programmed by the central unit 100, following the trajectory of the print head, in order to produce the corrected shape of the strips as predetermined by the supervisor 101.

[0084] In addition, a masking function for edges B1 and B2 of strip 50 is advantageously programmed by the central unit in order to mask printing discontinuities of these edges.

[0085] The invention is not limited to the example described and illustrated. For example, it is possible to rotate the structure being processed using a ring driven by two geared motors to create the drive system, or by means of a backlash compensation device.

[0086] Furthermore, the method of topographic surveying is chosen between a scanner for a surface survey, a profilometer for a line survey, and a group of at least three rangefinders for a point survey.

[0087] Instead of the robot shown, a linear axis can move the end effector suspended from a carriage, with at least three degrees of freedom relative to the carriage to create an alternative robot, ensuring the print head remains aligned with the surface. Printing successive strips at very short intervals, for example 1 mm, allows for ink spreading before drying; the UV lamp is then moved accordingly.

Claims

DEMANDS 1. A method for printing an image by inkjet on a non-developable surface area (20), characterized in that it comprises the following successive steps: - to mount in rotation a structure (7) presenting said zone (20) on a receiving axis (X'X) motorized by steps (6) and extending in a plane called horizontal parallel to a given ground (S); - fix to the ground a chassis (1) incorporating the receiving axis (X'X) of the structure (7), the chassis being designed and calculated by finite elements; - arrange an inkjet effector (8) at the end of a robotic arm (31) comprising a print head (80) consisting of at least one line (8a to 8d) of nozzles (B1), the arm (31) being articulated so that the head (80) moves in a vertical plane (V) perpendicular to the ground (S) and passing through the receiving axis (X'X); - to carry out a survey of topographic data (12) of the area to be printed (20) in connection with visualization data (13) of this area (20) and transmit this data to a digital application for controlling the trajectory of the arm (31); - determine the trajectory of the print head (80) and the print tops by the trajectory control application from data of the image to be printed previously recorded and cut into strips (50) according to the topographic (12) and visualization (13) data; - modify the strips (50) by the prior application of at least one correction parameter which compensates for an image distortion caused by printing on the left surface; - adjust the step size of the motorization (6) and the drive speed of the receiving axis (X'X) according to the strips to be printed; - transmit the trajectory and print top data to a digital print control application which reproduces, by inkjet printing, after superimposing the trajectory of the print head (80) and the area to be printed (20), the image on the surface area to be printed cut by successive modified strips, taking this area (20) as the sole basic reference of the trajectory of the arm (31), of the ink jet of the print head (80) and of the drive rotation by step of the surface to be printed with return of the print head (80) at each strip.

2. A printing method according to claim 1, wherein the image to be printed is pre-deformed by the application of a correction parameter causing the modification of each strip according to an inverse deformation of each image strip.

3. A printing method according to any one of claims 1 or 2, wherein a sheet edge masking correction function (B1, B2) is implemented in order to mask printing discontinuities of these edges.

4. A printing method according to any one of claims 2 or 3 wherein, in the case where the surface of the structure (7) has a barrel shape, the image deformation parameter causes a progressive approach of each strip (50) from a central axis (Y'Y) of the strip perpendicular to the axis of rotation (X'X) to the ends (E1 to E4), each strip and therefore the resulting image progressively shrinking towards the ends (E1 to E4).

5. A printing method according to any one of claims 1 to 4, wherein the rotation of the area to be printed (20) is adjusted so that the printing made by each strip (50) fits together with that of the previous strip in a contiguous manner.

6. A printing method according to any one of claims 1 to 4, wherein the rotation of the area to be printed (20) is adjusted so that the printing made by each strip (50) adjusts to that of the previous strip by leaving a space of predetermined width.

7. A printing method according to any one of claims 1 to 4, wherein the rotation of the surface to be printed (20) is adjusted so that the printing made by each strip adjusts to that of the previous strip with an overlap of predetermined width and a reduced printing density so that this overlap compensates for the reduction in density.

8. A printing machine for a surface with a curved shape, implementing the method according to any one of the preceding claims, characterized in The machine comprises a rigid metal alloy chassis (1) fixed to the ground (1), on which are also fixed a rotating drum (2), mounted on a shaft (X1) around the receiving axis (X'X) of the structure (7), the foot (30) of the inkjet printing robot (3), a control bay (4) for this robot (3) linked to a PLC (51) for controlling the trajectory of the robot (3), and a stepper motor (6) for driving the drum (2), the left-hand structure to be printed (7) being fixed to the rotating drum (2). The machine also includes the end effector (8) mounted at one end of the robot arm (31), this end effector (8) integrating the print head (80), a UV lamp (14) for polymerizing the ink, a camera (13) for detecting the position of the end effector, and a topographic surveying means (12a to 12c; 15) for tracking the trajectory of the arm (31), mounted at the other end of the base of the arm (31) a platform (81) accommodates a set of ink reservoirs (91),A bundle of flexible tubes (10) supplies ink between the reservoirs (91) and the effector (8) via circulation pumps (9). The machine also includes a supervisor (101) for controlling the trajectory of the arm (31), in which the digital application for controlling the arm's trajectory is installed. The supervisor is bilaterally linked to a central unit (100) that houses the digital printing application. Network synchronization cables (33) connect the supervisor (101) to the central unit (100), to the motor (6) of the receiving shaft (X1) of the structure (7), to the PLC (51) controlling the motorization of the arm's trajectory (31), to the camera (13), to the UV lamp (14), and to topographic surveying equipment (12) whose data is managed by the supervisor (101) after receiving the image data to be reproduced, extracted from the image file originating from the central unit. (100)., 9. Printing machine according to claim 8, in which the motorization (6) consists of a geared motor.

10. Printing machine according to any one of claims 8 and 9, wherein the structure (7) is fixed to the drum by discs (21).

11. Printing machine according to any one of claims 8 to 10, wherein the ink supply tubes (10) are housed in a sheath (10g) maintained at an ink fluidity temperature.

12. Printing machine according to any one of claims 8 to 11, wherein the effector (8) delivers at least four colors and comprises aligned printing nozzles (Bx).

13. Printing machine according to any one of claims 8 to 12, wherein the print head (80) has at least four lines of nozzles (8a to 8d), each line of nozzles delivering a base colour.

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