METHOD FOR PRINTING A LEFT-HANDED SURFACE AND IMPLEMENTATION MACHINE

Abstract

The invention relates to a method of inkjet printing on an area (20) of a structure (7) with a warped surface using an articulated robot (3). The structure is mounted for rotation on a motorized drum (2) (6) on a chassis (1) fixed 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 visualization data (13) of the area (20) are transmitted to a supervisor (101) which, after receiving the image data to be printed from a central printing unit (100), calculates the trajectory of the print head and the cutting of the image into strips (50) corrected to compensate for the printing distortion on a warped surface. This data is transmitted to the central unit (100) to print the image on the area (20), using this area as the sole reference frame. Abstract figure: Figure 1

Description

Title of the invention: METHOD FOR PRINTING A LEFT-HANDED SURFACE AND IMPLEMENTATION MACHINE technical field

[0001] 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, barrel-shaped. In particular, the invention applies to the printing of technical markings and logos on aircraft nacelles. The invention also relates to a machine for implementing such a method.

[0002] The invention also applies in any field where markings, decorations or logos are applied to curved surfaces: automotive, railway, maritime or building sectors.

[0003] Inkjet printing can be carried out on substrates of various compositions, such as glass, ceramic, plastic or metal. Since this printing is carried out without direct contact, it can be performed on flat surfaces or surfaces adjustable in a tangent plane.

[0004] Inkjet technology consists of projecting microdroplets of ink through the nozzles of a print head onto the surface of the substrate to be printed. The inkjet commands, the movements of the print head and the substrate to be printed are coordinated by a processing unit according to the pattern to be produced. STATE OF THE ART

[0005] Traditionally, this operation is carried out in painting using compressed air spray guns and requires numerous resources: masking consumables 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 carried out by operators, it is difficult to guarantee reproducibility of the result.

[0006] Inkjet printing has several advantages over the application of paint or adhesive, including better precision and reproducibility of the pattern to be applied, reduced cycle time, simultaneous printing of all colors, reduced product consumption when necessary, no single-use consumables, and consistent and measurable quality of result.

[0007] Solutions enabling inkjet printing on non-developable surfaces, such as a barrel-shaped 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 parts.

[0008] It is known, for example, from US patent 11207896, that data from an internal robot positioning system—as well as data from a reference system including a stationary reference external to the robot—are used to calculate an estimate of the position, velocity, and acceleration of the print head relative to the surface. When the print head moves along the surface during printing, that is, when the print head is moved while ink is ejected from the print head nozzles, the positioning of the print head and the activation of the print head nozzles are controlled based on the estimate.

[0009] Furthermore, the print head of document US 2015009254 contains a plurality of inkjet nozzles for ejecting ink to a distant position by supplying pressurized air to each ink reservoir. This head is mounted on a linear array so as to be able to 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, with the drive of predetermined nozzles in the head being controlled in conjunction with this position information. Description of the invention

[0010] The use of equipment mounted on a mobile ground structure requires a significant lever arm, which makes it impossible to print ungainly surface aircraft parts, such as nacelles, with sufficient precision and fidelity. In particular, such ground installations do not guarantee consistency or fidelity in producing the same print on different aircraft, as the prints must be identical in geometry and colorimetry. Numerous rework operations are therefore necessary to overcome this limitation. In particular, US patent 2015009254 uses a print head guide rail, which limits the printable areas to flat or cylindrical surfaces.

[0011] The present invention aims to avoid such rework by providing a high-precision print, reproducible and conforming in geometry and colorimetry to an original pattern.

[0012] To this end, the present invention proposes using the surface to be treated as the sole reference frame for the 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 curved surfaces.

[0013] More specifically, the present invention relates to a method for printing an image by inkjet onto a non-developable surface area, referred to as a warped or deformed area. This method comprises the following steps: - 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; - 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; - 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; - 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; - 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; - 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; - adjust the step size of the motorization and the drive speed of the receiving axis 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 print head trajectory and the area to be printed, the image onto the surface area to be printed, cut in successive modified strips, taking this area as the sole reference point for the arm trajectory, the print head inkjet, and the rotation of the print surface by step with return of the print head at each strip.

[0014] 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 strip according to an inverse distortion of each image strip. Alternatively, or in conjunction with the application of the correction parameter, a strip edge masking correction function can be implemented to mask printing discontinuities at these edges.

[0015] Advantageously, rotating the structure to be printed makes it possible to limit the trajectory that the inkjet effector follows. Moving the print head in a vertical plane reduces printing inaccuracies above the surface to be treated, which serves as a reference.

[0016] Furthermore, the speed and deceleration of the robot arm are adjusted at the beginning of printing each strip so that the printed ends of the strips are aligned.

[0017] 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.

[0018] According to advantageous forms of implementation: - 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; - 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; - 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; - 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.

[0019] The invention also relates to a printing machine dedicated to an advantageous implementation of the printing process defined above. This machine comprises a rigid metal alloy chassis fixed to the floor, on which are also fixed a rotating drum, mounted on a shaft around the receiving axis of the structure, the base of the inkjet printing robot, and a control bay for this robot connected to a robot trajectory control system, and a drum drive motor, the so-called left or deformed structure to be printed being fixed on the rotating drum.

[0020] 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 for topographic surveying to track the trajectory of the arm.

[0021] A platform mounted at the other end of the base of the arm accommodates a set of ink tanks, a bundle of flexible tubes ensures the supply of ink between a set of ink tanks and the effector via ink circulation pumps.

[0022] 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.

[0023] Synchronization network cables connect the supervisor to the central unit, to the motorization of the receiving shaft of the structure, to the control unit for the motorization of the trajectory of the arm, to the camera, to the UV lamp and by means of topographic surveys whose data are managed by the supervisor after receiving the data of the image to be reproduced extracted from the image file from the central unit.

[0024] Furthermore, the chassis is advantageously welded by spot welding or equivalent, so as to present a rigidity which allows the components of the equipment mounted on this chassis - robot and structure to be treated - to be free from any play, deformations or vibrations.

[0025] According to preferred characteristics: - the motorization consists of a geared motor; - the structure is attached to the drum by discs; - the ink supply tubes are housed in a sheath maintaining an ink fluidity temperature, for example with heating resistors; - the effector delivers at least four colors and has aligned print nozzles; - the print head has at least four lines of nozzles to simplify the path of the robot arm, each line of nozzles delivering a base color. PRESENTATION OF THE FIGURES

[0026] 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:

[0027] - Fig. 1, an overall perspective view of an example of a printing machine according to the present invention;

[0028] - the [Fig.2], a front overall view of the machine of the [Fig.1];

[0029] - [Fig. 3], a more detailed perspective view of the robot equipped with the end effector printing;

[0030] - the [Fig.4], a perspective view before the effector of the machine views previous ones equipped with rangefinders and a camera;

[0031] - [Fig. 5], a rear perspective view of the effector of [Fig. 4] showing in in particular the UV lamp;

[0032] - [Fig. 6], a bottom view of the effector showing the nozzle lines of the head printing;

[0033] - the [Fig.7], a functional diagram of the main components of the machine according to the invention;

[0034] - [Fig. 8], a diagram of the physical connections between the components relating to printing according to the invention, and

[0035] - the [Fig.9], a diagram showing the pre-processing of the image in the case of a printing on a barrel-type surface. DETAILED DESCRIPTION

[0036] In the figures, identical reference numerals 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.

[0037] The overall perspective view of [Fig. 1] and the front view of [Fig. 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 [Fig. 8]). With reference to the perspective view of [Fig. 3], the robot 3 is shown in more detail with a printing end effector 8 at its end and a platform 81 at its other end, referred to as the base.

[0038] The chassis 1 is composed of welded metal hollow beams 11 arranged in a cradle shape to support the drum 2 without deformation. The drum 2 is itself driven in rotation by steps 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 XI with axis X'X. an aircraft nacelle 7 in the example, and fixes this nacelle 7 onto the drum 2 via discs 21.

[0039] 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 end effector 8 has a four-color print head 80 and, fixed 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 the 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 end effector 8 along the arm 31.

[0040] The entire system is managed by a supervisor 101 incorporating a digital application for controlling the trajectory of the robot arm 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 further on with reference to [Fig. 8]) in conjunction with a central unit 100. This central unit 100 incorporates a digital application for controlling the printing. 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 unit 100 can be separate or integrated within a single digital entity EN1 (shown in dashed lines in [Fig. 2]), and the applications can be grouped into a single, more powerful processor.

[0041] The robot arm 31 is controlled to move along a trajectory in space following a topographic survey of the surface area to be treated 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 50 (see [Fig. 1]) is controlled 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 carry out a topographic surface survey. The scanner 15 and the extension 82 are shown in dashed lines in [Fig. 4].

[0042] Figures 3 and 4 also show the ink supply tubes 10 gathered in a common temperature-protective sheath 10g. In particular, this temperature control can be achieved by heating elements (not visible) with adjustable intensity to maintain a fixed temperature. Alternatively, the sheath 10g is made of a flexible and insulating plastic material, for example, layers of polyethylene.

[0043] 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 the supervisor 101 to be printed extracted from the file. The central unit 100 also allows calibration of the dimension, color as well as the adjustment of an image correction parameter in order to cause edge effects of each of the strips to be printed successively on the area 20 of surface to be treated (see further in reference to [Fig.9]).

[0044] The strips 50 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 being 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.

[0045] In addition, a UV lamp 14 (see [Fig.5]), mounted on the effector 8, allows the ink successively deposited on said area 20 during the trajectory of the robot arm 31 to be polymerized.

[0046] The operation of the machine is ensured by the supervisor 101. This supervisor first performs, for the first strip, a simulation of trajectory in space along the X'X axis of the nacelle 7, based on the topographic survey of the area to be treated 20, the ink jets of the print head 80 then extending in the vertical plane V (see [Fig.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.

[0047] 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 [Fig.7]).

[0048] During movement, the robot's trajectory, defined by the supervisor 101, is secured—for example, by anti-collision measures—and, if necessary, recalculated based on information received from the rangefinders 12a, 12b, and 12c. A predefined distance, 4 mm in this example, is maintained between the nozzle tips and the surface to be treated, and is also received from the camera 13 to manage the proximity of successive strips. In this example, a continuous alignment is thus maintained between two successive strips.

[0049] 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 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 application 101, following an angular command determined based on a print width predetermined by an image segmentation performed and calibrated by the central unit 100.

[0050] 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 the operation, it is thus possible to print on several strips from the same image file.

[0051] The bottom view of the print head 8 of [Fig.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.

[0052] Figure 7 shows the functional connections 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:

[0053] - receives position data of the area to be printed from the topography, provided in the example by telemetry 12, visualization data of this area from camera 13, as well as image data to be printed extracted from the image file from central unit 100;

[0054] - cuts the image received from the central unit 100 into strips of equal length to that of the zone and width equal 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 [Fig.6]) as a function of the position and the shape correction of each strip to be printed in the zone 20 (see further on with reference to [Fig.9]);

[0055] - activates the 6-axis rotating motor of the nacelle and the 6-axis tracking motor of the trajectory of the robot arm 31 via an automaton 51 (see below with reference to [Fig.8]) in order to move the arm 31 according to the trajectory determined according to the data received;

[0056] - transmits the data to the print control application of the central processing unit 100 of the trajectory of the effector and the triggering moments of the impression tops, and

[0057] - 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 that ink.

[0058] With regard to 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 top times provided by the supervisor after superimposing the print head trajectory and the area to print. This supply is controlled according to data from a prior correction processing relating to the shape of the strips (see below with reference to [Fig.9]).

[0059] Printing is performed at each instant by taking the area to be printed 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 surface to be printed, with the print head returning to its starting position at each strip. Each strip has a width and a length corresponding respectively to the amplitude and the speed—equal to the number of steps per unit of time—of the drive step.

[0060] 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 controller 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 controlling the ink tanks 91. The ink reaches the end effector 8 via the tubes 10 integrated into the sheath 10g.

[0061] 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.

[0062] With reference to [Fig. 9], a diagram shows an example of preprocessing the image to be printed in the case of printing on a barrel-shaped surface, thus reproducing the "stave effect". The image recorded in the central unit 100 is selected and processed at the supervisor 101 to determine the trajectory of the print head and the shape of the strips corrected for the stave effect.

[0063] In this example, this processing consists of shrinking each strip 50 of the image, initially rectangular, at its ends by applying a correction parameter that produces a continuous image deformation. This application causes a progressive approach from a central axis Y'Y of the strip 50, perpendicular to the rotation axis X'X of the rotation shaft XI, to its ends El to E4.

[0064] Each strip, and therefore the image constructed from all 50 strips, is thus progressively shrunk towards its ends by a selection of active nozzles. The shrinking is achieved by activating all the nozzles in the center of the strip and progressively deactivating an increasing number of nozzles towards its ends. The print commands corresponding to the successive activation of the Bx nozzles (see [Fig. 6]) selected by the supervisor 101 are programmed by the central processing unit. 100 following the trajectory of the print head, in order to achieve the corrected shape of the strips as predetermined by the supervisor 101.

[0065] In addition, a function for masking edges B1 and B2 of strip 50 is advantageously programmed by the central unit in order to mask printing discontinuities of these edges.

[0066] The invention is not limited to the example described and illustrated. It is, for example, possible to rotate the structure to be treated using a ring driven by two geared motors to constitute the drive system, or by a backlash compensation device.

[0067] Furthermore, the means 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.

[0068] In place of the robot shown, a linear axis can ensure the movement of the end effector suspended from a carriage, with at least three degrees of freedom relative to it to constitute an alternative robot, in order to guarantee the normality of the print head with respect to the surface.

[0069] A non-contiguous printing of successive strips at a very small distance, for example 1 mm, makes it possible to take into account the spreading of the ink before drying, the UV lamp is then moved accordingly.

Claims

1. Demands 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 (Bl), 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); - 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 trajectory data and print tops to a digital print control application which reproduces by inkjet, after superposition of the trajectory of the print head (80) and the area to be printed (20), the image on the area of ​​surface 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 step-by-step drive rotation 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 each strip (50) to move progressively closer from a central axis (Y'Y) of the strip perpendicular to the axis of rotation (X'X) to the ends (El to E4), each strip and therefore the resulting image gradually shrinking towards the ends (El 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 done 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 printing surface (20) is adjusted so that the print produced by each strip aligns with that of the preceding strip with an overlap of predetermined width and a reduced printing density so that this overlay compensates for the decrease in density.

8. A printing machine for a left-handed surface implementing the method according to any one of the preceding claims, characterized in that it comprises a rigid metal alloy chassis (1) fixed to the floor (1) on which are also fixed a rotating drum (2), mounted on a shaft (XI) 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) in connection with a robot trajectory control PLC (51), and a stepper motor (6) for driving the drum (2), the left-handed structure to be printed (7) being fixed on the rotating drum (2), the machine also comprises 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) ensures the supply of ink between the reservoirs (91) and the end effector (8) via circulation pumps (9); and the machine also includes a supervisor (101) for controlling the trajectory of the arm (31), in which the digital application for the arm's trajectory is installed, the supervisor being in bilateral communication with a central unit (100) which houses the digital printing application; synchronization network cables (33) linking the supervisor (101) to the central unit (100), to the motor (6) of the receiving shaft (XI) of the structure (7), to the PLC (51) for controlling motorization of the arm's trajectory (31), to the camera (13),using a UV lamp (14) and topographic surveys (12) whose data is managed by the supervisor (101) after receiving the image data to be reproduced extracted from the image file from the central unit (100).

9. Printing machine according to claim 8, wherein 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 flow 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 print 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 color.