Digital printing module

Abstract

The invention relates to a digital printing module (22) comprising at least one printing head (25) having a nozzle plate (27) provided with a plurality of nozzles (29). The print head is mounted in a rotatable frame (106) that allows the print head to rotate between a printing position (A) in which the nozzle plate faces vertically upward and a cleaning position (B) in which the nozzle plate faces vertically downward.

Description

Technical Field

[0001] The present invention relates to a digital printing module which is particularly suitable for printing on paper, cardboard and plastics. Such a digital printing module can be integrated into a converting machine configured to produce folding boxes and similar packaging containers. Background Art

[0002] Digital inkjet printing is commonly used to print images on packaging blanks, such as cardboard or cartons. During digital inkjet printing, the inkjet print head is positioned so that the print nozzles face downward, and ink droplets are ejected under the force of gravity. This is advantageous for ensuring that the droplets are transported in a controlled, linear direction until they are deposited on the blank.

[0003] However, for certain applications, such as in converting machines, different mechanical operations are required on the blanks. Converting machines, such as folder-gluers, are used to produce paperboard and cardboard boxes. These machines are configured to receive cut blanks, then fold and glue them together to form folding boxes or other similar packaging containers.

[0004] The cut blank is usually printed on the side that will be made into the outside of the container.In a folder-gluer, due to the folding operation, the printed side needs to be placed in the feeder with its printed side facing downwards.

[0005] Document EP2512792B1 discloses a folder-gluer with a digital printing device arranged to print in the direction of gravity in a conventional manner. The device in EP2512792B1 has a specific transport path that allows the blank to be printed from above and then turned over to a position with the printed surface facing downwards. Summary of the Invention

[0006] In view of the prior art, an object of the present invention is to provide a digital printing device for a converting machine, which is capable of printing on the bottom surface of a blank without turning the blank over.

[0007] This object is achieved by a digital printing module according to claim 1 and a converter according to claim 10. According to a first aspect of the invention, a digital printing module is provided, comprising at least one print head, the print head comprising a nozzle plate provided with a plurality of nozzles. The print head is mounted in a rotatable frame that allows the print head to be rotated between a printing position, in which the nozzle plate faces vertically upward, and a cleaning position, in which the nozzle plate faces vertically downward.

[0008] The present invention is based on such recognition: if the print head can be positioned in a specific cleaning position, the print head can be cleaned conveniently. In this cleaning position, the accessibility of the print head is further improved.

[0009] In one embodiment, multiple print heads are arranged side by side in clusters, wherein the clusters are located in a frame. Multiple clusters can also be combined together. In a related embodiment, a digital printing module can include at least one printing assembly, wherein the printing assembly includes multiple clusters located in a common frame.

[0010] In an embodiment, the digital printing module includes a first printing assembly and a second printing assembly, each printing assembly including a plurality of clusters located in a separate co-located frame, and wherein the first printing assembly is in a cleaning position and the second cluster is in a printing position.

[0011] In an embodiment, the digital printing module further comprises a cleaning device, which is provided with a movable cleaning component, the cleaning component being configured to move on the nozzle plate of at least one printing head and clean the nozzle plate of at least one printing head. The cleaning module may be located on a side of the digital printing module.

[0012] In an embodiment, the cleaning component comprises a flushing channel provided with first and second elongated seals, and wherein the cleaning module further comprises a cleaning liquid reservoir and a liquid circulation pump configured to supply and withdraw liquid from the cleaning channel.

[0013] In an embodiment, the frame is connected to the first and second rails and the displacement device, and wherein the displacement device is configured to displace the cleaning device under the digital printing module when a need for cleaning is detected.

[0014] In an embodiment, the first pressure sensor is located upstream of the printhead and the second pressure sensor is located downstream of the printhead, and wherein the need for cleaning is identified when resistance on at least one of the printheads exceeds a resistance threshold.

[0015] According to a second aspect of the present invention, a converting machine is provided that is configured to receive blanks and fold and glue the blanks to form a folding box, wherein the converting machine includes a digital printing module, a feeder module, a folding module, and a gluing module according to any of the aforementioned embodiments. The folding module is preferably configured to fold the side flaps of the blank upwards. In this manner, the printed pattern from the digital printing module is located on the outer surface of the packaging element.

[0016] Preferably, the digital printing module is located upstream of the folding module in the conveying direction of the blanks.

[0017] In an embodiment, the converting machine further comprises an optical inspection module, wherein the optical inspection system is configured to detect the position of ink drops on the blank and determine a need for cleaning the at least one print head.

[0018] The optical inspection system may be configured to determine a valid printing area on the blank, the valid printing area representing an area that can be printed without printing errors.

[0019] In an embodiment, the control unit of the inspection module is configured to propose a displacement of the printing area on the blank. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will now be described with reference to the accompanying drawings, in which like features are indicated by like reference numerals, and in which:

[0021] - Figure 1 is a schematic diagram of a converting machine in a folder-gluer configuration;

[0022] - Figure 2 Schematic top view of the blank;

[0023] - Figure 3 It is a three-dimensional schematic diagram of the printing cluster;

[0024] - Figure 4 is a schematic diagram of a fluid system of a digital printing module according to an embodiment of the present invention;

[0025] - Figure 5 is a schematic diagram of a digital printing module according to an embodiment of the present invention;

[0026] - Figure 6 is a schematic diagram of a digital printing module according to another embodiment of the present invention;

[0027] - Figure 7 is a three-dimensional schematic diagram of a vacuum transporter;

[0028] - Figure 8 is a perspective schematic diagram of a plurality of printing clusters installed in a common frame according to an embodiment of the present invention;

[0029] - Figure 9 is a schematic diagram of the cleaning module;

[0030] - Figures 10a to 10c Schematic diagram of the printing cluster in the working position and at the beginning and end of the cleaning position;

[0031] - Figure 11 is a schematic diagram of a digital printing module including two printing components. DETAILED DESCRIPTION

[0032] The present invention can be used alone for printing purposes and in the form of a printing module. It can also be used with various types of converting machines, such as folder-gluers, flexo folder-gluers, and rotary die-cutters. However, to simplify the present description, reference will be made herein only to folder-gluers.

[0033] See especially Figure 1 and Figure 2 1 , which shows a folder-gluer 1 and a blank 2 to be processed therein. The folder-gluer 1 is configured to receive a cut blank 2 and then fold and glue it to form a packaging element. The packaging element may be a folding box or other folded and glued packaging container. The blank 2 is transported through the converting machine 1 along a transport path P.

[0034] The folder-gluer 1 may include a series of different workstations in the form of modules. From the inlet to the outlet and along the transport direction T, these modules may include: a feeder module 10, an alignment module 11, a folding and pre-breaking module 12, a gluing module 14, and a folding module 16. The folder-gluer 1 may also include a main user interface 13 and an inspection module 18. The folding module 16 is preferably configured to fold the side flaps F1, F2 of the blank 2 upward. In this manner, the printed pattern from the digital printing module 22 is positioned on the outer surface of the packaging element.

[0035] The alignment module 11 is arranged downstream of the feeder module 10 in the transport direction T and is configured to align the blanks 2 laterally to a predetermined lateral position. The predetermined lateral position is defined by the position of the longitudinal crease lines 4 in the conversion machine 1 and the positions of the folding and auxiliary tools. Thus, the alignment module 11 is configured to align the blanks 2 in a direction D perpendicular to the transport direction T. Optionally, a discharge module 17 is located after the folding module 16. The discharge module can be configured as described in document EP2976279A1.

[0036] After the gluing and folding modules, a delivery module and a conditioning zone 21 may be provided to count the shingled flow of folded boxes and to separate them into individual batches.

[0037] The conversion machine 1 further comprises a transport system 19 comprising a conveyor such as endless belts and rollers configured to transport the blanks 2 in a transport direction T. The conversion machine 1 further comprises a central control circuit 20 configured to control the operation of the conversion machine 1 .

[0038] The present converting machine 1 further comprises a digital printing module 22 in the form of an inkjet printing module 22. Preferably, the digital printing module 22 is located downstream of the registration module 11. The digital printing module 22 is located upstream of the folding module 16 in the transport direction T of the blanks 2.

[0039] like Figure 3 and Figure 4As best seen in FIG, inkjet printing module 22 includes an inkjet printing system 30 comprising at least one printhead 25. Each printhead 25 includes a nozzle plate 27. Preferably, inkjet printing system 30 includes a plurality of printheads 25 arranged in printing clusters 24. Each cluster 24 includes a plurality of printheads 25 grouped and attached together.

[0040] The printing clusters 24 are arranged with nozzle plates 27 located below the transport path P of the blanks 2. Each printing cluster 24 can be fluidically connected to a separate ink reservoir 32. In order to print in several different colors, the inkjet printing system 30 can include multiple printing clusters 24 and ink reservoirs 32.

[0041] like Figure 4 As schematically shown in FIG, inkjet printing system 30 includes an ink reservoir 32, which may include a primary reservoir 33 and a secondary reservoir 34. Primary reservoir 33 is configured to store a large amount of ink, such as 5 to 20 liters or even up to 1000 liters of ink. Secondary reservoir 34 is configured to store a smaller amount of ink than primary reservoir 33. Secondary reservoir 34 may be connected to each individual printhead 25 in printing cluster 24 in a closed-loop manner. A heating system 35 is thermally connected to the ink from second reservoir 34. Heating system 35 may include first and second heating elements 36, 37 configured to heat ink in a fluid circuit upstream of printhead 25 and / or in printhead 25.

[0042] The print head 25 includes a fluid inlet 38 through which ink may enter the print head 25 , a fluid outlet 40 through which ink may exit the print head 25 , and an ink channel 42 connecting the fluid inlet 38 with the fluid outlet 40 .

[0043] The inlet pump 44 and the first pressure sensor 46 are arranged on the fluid inlet circuit 47 of the print head 25. The inlet pump 44 is located upstream of the print head. Preferably, the inlet pump is located between the primary reservoir 33 and the secondary reservoir 34.

[0044] The first pressure sensor 46 is located between the second fluid reservoir 34 and the print head 25. Preferably, the first pressure sensor 46 is located at the fluid inlet 38 of the print head 25.

[0045] An outlet pump 45 is located on an outlet circuit 49 from the print head 25. A second pressure sensor 48 is arranged on the fluid outlet circuit 49 from the print head 25. The inlet pump 44 and the outlet pump 45 cooperate to mechanically supply ink to the print head 25 and mechanically withdraw ink from the print head 25. In this manner, the ink flow F is mechanically controlled on the print head 25. This mechanical control of the fluid flow F on the print head 25 reduces the effect of gravity on the ink flow F.

[0046] To reduce pulsations in the ink flow near the printhead 25 , a first dampener 50 may be located downstream of the inlet pump 44 .

[0047] Furthermore, the second damper 52 is located upstream of the outlet pump 45. The first and second dampers 50, 52 may comprise containers comprising air bladders that form air cushions that absorb pulsations when fluid enters the dampers 50, 52.

[0048] In this manner, pulsations in the ink flow F in the print head 25 can be reduced. The first damper 50 reduces upstream pulsations in the ink flow F, and the second damper 52 reduces downstream pulsations in the ink flow F. Thus, a more continuous ink flow F is obtained in the ink channel 42 in the print head 25.

[0049] The inkjet printing system 30 further includes a control circuit 56. The control circuit 56 includes a control unit 58 and a memory 60. The inlet pump 44, the outlet pump 45, and the first and second pressure sensors 48, 50 are connected to the control circuit 56. The first and second pressure sensors 48, 50 are configured to continuously provide their respective inlet pressures P1 and outlet pressures P2 to the control unit 58. Based on the detected inlet and outlet pressures P1, P2, the control unit 58 determines the meniscus pressure Pm.

[0050] In particular, too high a meniscus pressure Pm may result in air ingress, while too low a meniscus pressure Pm may cause nozzle plate overflow. In addition, pulsations in the meniscus pressure Pm may result in periodic effects in the printed output. The control unit 58 is further configured to modify the rpm of the outlet pumps 44, 45 and correct the meniscus pressure Pm. Figure 1 、 5 As best seen in Figures 6 and 7, at the exit of the alignment module 11, the vacuum transfer conveyor 60 is positioned with its suction surface facing the top side S1 of the blank 2. The vacuum transfer conveyor 60 ensures that the blank 2 is immediately located and gripped at the exit of the alignment module 11. Figure 7 As shown in FIG, the vacuum transfer conveyor 60 may include a conveyor belt 61 provided with a suction port 63 and having a width W greater than the width of the blank 2.

[0051] The vacuum transport conveyor 60 may include a plurality of suction boxes 64. The vacuum suction boxes may include internal shields 65 that limit the lateral suction distance (LD) of the vacuum transport conveyor 60. The internal shields 65 are automatically displaced to laterally limit the suction force and align the shields with the width of the blank 2. In this way, disturbances and effects caused by the suction force of uncovered suction openings 63 in the conveyor belt 61 can be reduced.

[0052] Preferably, the blank 2 is transported by the vacuum transfer conveyor 60 only when the printed pattern is deposited on the blank 2. Therefore, the blank 2 is no longer retained in the alignment module 11 when the pattern is deposited on the blank 2. This avoids potential displacement of the blank 2 caused by any mechanical contact elements, such as guides in the alignment module 11.

[0053] The print head 25 is located below the vacuum transport conveyor 60 and is configured to print on the bottom surface S2 of the blank 2 according to a signal from the transport sensor 71. The print head 25 is arranged to discharge liquid in a direction opposite to the direction G of gravity.

[0054] The blanks 2 are longitudinally shifted in register in the transport direction T and their arrival times at the printing head 25 vary. If the position of the blanks 2 is not controlled and corrected, there is a risk that the printed image is not placed at the intended correct position on the blank 2.

[0055] In order to ensure that printing is performed at the correct longitudinal position on the blank 2 , the printing module 22 preferably comprises a register control system 70 .

[0056] like Figure 1 、 5 As best seen in Figures 6 and 7, the register control system 70 includes a transport sensor 71, a control unit 72, and a memory 74. The transport sensor 71 is located upstream of the print head 25. The sensor 71 may be an optical sensor with background suppression. The transport sensor 71 is configured to detect the position of the leading edge E1 or the trailing edge E2 of the blank 2 as the blank 2 is transported by the vacuum transport conveyor 60.

[0057] As the blank passes through, the transport sensor 71 provides a detection signal to the control unit 72. The control unit 72 then calculates the estimated arrival time of the blank 2 at the printing head 25. The estimated arrival time can be calculated by adding the extra transport time to the detection time. The extra transport time can be calculated from the transport speed of the vacuum transport conveyor 60.

[0058] The memory 74 includes programming that allows the control unit 72 to calculate the arrival time of each print head 25 and the desired jet activation time.

[0059] When printing is performed near the outer edges E1, E2, E3, and E4 of the blank 2, some of the suction ports 63 in the vacuum conveyor 60 are not covered by the blank 2, and these suction ports 63 are close to the ink nozzles. This may cause some ink droplets to be sucked into the vacuum conveyor 60, and their trajectories may also be changed due to the aerodynamic effects of the vacuum conveyor 60. Therefore, when the trajectory of the ink droplets changes, the accuracy of the printed pattern will be reduced. Therefore, it is advantageous to limit the digital printing area to the center area of ​​the blank 2 and define an effective printing area EF (e.g., Figure 2 ).

[0060] The effective printing area EF is limited by the distortion effects caused by the vacuum transfer conveyor 60. The distortion effects are caused by the following factors:

[0061] - the size of the blank 2; therefore, the smaller the blank 2, the greater the calibrated suction force of the vacuum transport conveyor 60. There will be fewer obstructed suction openings 63 in the vacuum transport conveyor 60 for holding the blank 2, and each suction opening 63 will need to exert a stronger suction force.

[0062] The geometry of the blank 2 and the shape of the edges close to the printed pattern: The shorter the side edges E3, E4 of the blank 2 in the transport direction T, the more unobstructed the suction openings 63 are and the greater the distortion effect at the side edges E3, E4 of the blank 2.

[0063] The distortion of the droplets can be visually detected by an operator after inspecting the blank 2 or the vacuum transfer conveyor 60 . The inspection module 18 is preferably located downstream of the digital printing module 22 .

[0064] The inspection module 18 preferably includes a camera and lighting system as disclosed in document EP3221221. The inspection device 18 also includes control circuitry 80. The inspection module 18 can be configured to inspect the position of printed graphics and text and compare them to PDF specifications, as well as inspect foils and varnishes. The inspection module 18 can also be configured to perform color measurements to verify that the printed colors match PDF printing specifications and to detect the position of embossed elements (e.g., pads or Braille embossing). Distortion effects from an unobstructed suction port 63 can also be detected by the inspection module 18.

[0065] The existing control circuit 80 of the detection module 18 can be configured to detect and calculate the distance of the register shift. In this way, the desired injection activation time can be adjusted.

[0066] The inspection module 18 can also determine the effective printing area EF. Thus, the inspection module 18 can define the effective printing area EF in which interference from the peripheral suction force is within a tolerable range. Therefore, the memory 84 of the inspection module 18 can include a program that enables the control unit 82 to calculate the tolerance distances from the outer blank edges E1, E2, E3, and E4 based on the geometry of the blank 2.

[0067] The control unit 82 can propose a displacement of the digital printing area. The proposed displacement can be visually displayed on the user interface / monitor 13. The control circuit 80 can generate a file of the proposed corrected image of the blank 2 and send it to the remote client for approval. The control system can also be connected to the remote client via a network. Optionally, the step of transmitting the proposed image file is performed only after approval of the instruction input into the interface 13 of the converter 1.

[0068] The inspection module 18 may also be configured to send corrective settings to the print head 25. Alternatively, the inspection module 18 may be configured to generate an error message to stop the converting machine 1.

[0069] The inspection module 18 may be configured to detect clogged or faulty nozzles. The control unit 82 is configured to calculate correction values ​​in order to activate adjacent nozzles in the nozzle plate 27 while deactivating the faulty nozzles.

[0070] The memory 84 may also include programming to allow the inspection module 18 to determine the need to clean the cluster 24 based on detected damage in the printed pattern.

[0071] Furthermore, the inspection module 18 may be configured to detect individual blanks 2 having printing errors. The individual blanks 2 may be marked by the discharge device 17 and discharged from the conversion machine 1 .

[0072] The printing cluster is configured to discharge ink in a direction opposite to the direction of gravity G. This allows printing on the bottom surface of the blank. However, some ink droplets may not remain on the blank and instead fall onto the printing cluster. When ink remains on the nozzle plate, some nozzles may become clogged. Clogged nozzles will cause undesirable printing defects in certain areas of the blank.

[0073] Figure 9 Schematically shown in FIG . Cleaning module 90 may include an elongated, movable cleaning member 91. The cleaning member includes a flushing channel 92 located between a first elongated seal 93a and a second elongated seal 93b. A pump 94 is configured to supply cleaning fluid from a reservoir 95 to an inlet of the flushing channel 92. The elongated cleaning member 91 is movable so as to clean the entire surface of the nozzle plate 27.

[0074] The cleaning module 90 may be fixedly located below the printing head 25 .

[0075] Alternatively and preferably, the cleaning module 90 is arranged laterally to the processing path P of the converter 1. The cleaning module 90 can be moved laterally from an inactive position outside the transport path P to a cleaning position below the print head 25. The cleaning module 90 can be moved in a direction D perpendicular to the transport direction T.

[0076] Since the flushing channel 92 is arranged so that the liquid is held by gravity, the nozzle plate 27 of the print head 25 needs to be arranged with the nozzle plate 27 facing vertically downward during cleaning.

[0077] An elongated cleaning member 91 is arranged to be laterally movable on the nozzle plate 27 of the print head 25. First and second guide rails 97a, 97b may support a first distal end 98a and a second distal end 98b of the cleaning member 91. A displacement device 100 including a motor 102 and an actuator 104 is connected to the cleaning member 91 and is configured to displace the cleaning member 91 along the guide rails 97a, 97b.

[0078] like Figures 10a to 10c As shown in FIG, a plurality of print heads 25 are assembled in a printing cluster 24. The printing cluster 24 is rotatably arranged between a printing position A and a cleaning position B. In the printing position A, the print nozzles 29 face vertically upward. Accordingly, in the cleaning position B, the print nozzles 29 face vertically downward.

[0079] like Figure 3 As shown in , each printing cluster 24 may be mounted in a separate frame 106 .

[0080] Alternatively, as Figure 8 As shown in FIG, a plurality of printing clusters 24 can be located in a common group frame 107 as a printing assembly 31. A plurality of printing assemblies 31 can also be provided, wherein groups of clusters 24 are housed in separate common group frames 107.

[0081] like Figure 11 As shown in , this enables simultaneous printing with the first printing cluster 24a or first printing assembly 31a and simultaneous cleaning of the second printing cluster 24b or printing module 31b. That is, one printing assembly 31a can be in printing position A and ejecting ink droplets onto the blank 2 while the other printing assembly 31b is in cleaning position B. However, if it is determined that printing is not required, the first and second printing assemblies 31a, 31b can operate simultaneously in printing position A.

[0082] The co-assembly frame 107 is rotatably connected to the structural frame 109 of the printing module 22. The co-assembly frame 107 of the printing assembly 31 is connected to the structural frame 109 in a first bracket 108a and a second bracket 108b. The brackets 108a and 108b are connected to the rotation axis R. The rotation axis R can be located at the center of gravity of the co-assembly frame 107.

[0083] The rotation of the printing assembly 31 is preferably performed after the printing assembly 31 is vertically displaced by a distance Df. Thus, the frame 109 can be vertically moved between the printing position A and the cleaning position B.

[0084] To allow the ink circuit to adapt to rotational motion, the ink conduits can be rotatably connected to the cluster 24. Typically, dried ink deposited on the nozzle plate 27 reduces the jetting capacity of the nozzles 29. This causes some nozzles 29 to become closed or partially clogged, causing them to stop dispensing ink or causing the ejected droplets to deviate. This results in the ejected droplets not being deposited at the desired locations on the blank 2.

[0085] As dry ink begins to accumulate on the nozzle plate 27, the resistance Ri on the print head 25 increases. When the resistance Ri exceeds the threshold Rt, the control unit 58 may send a message to the user interface 13 and stop the converter 1.

[0086] Additionally or alternatively, and as previously described, the optical inspection module 18 can also detect the need for cleaning. The inspection module 18 is configured to detect the position of printed elements on the blank 2 and compare the captured image with the expected image stored in the memory 60 of the control circuit 56.

Claims

1. A digital printing module (22) comprising at least one printing head (25), said printing head comprising a nozzle plate (27) provided with a plurality of nozzles (29), wherein said printing head is mounted in a rotatable frame (106) allowing said printing head to rotate between a printing position (A) and a cleaning position (B), wherein in said printing position (A) said nozzle plate faces vertically upwards and in said cleaning position (B) said nozzle plate faces vertically downwards.

2. The digital printing module according to claim 1, wherein: A plurality of print heads are arranged side-by-side in clusters (24), and wherein the clusters are located in the frame (106).

3. The digital printing module according to claim 2, wherein: The digital printing module comprises at least one printing assembly (31), wherein the printing assembly comprises a plurality of clusters located in a common group frame (107).

4. The digital printing module according to any one of the preceding claims, wherein: The digital printing module comprises a first printing assembly (31a) and a second printing assembly (31b), each printing assembly comprising a plurality of clusters located in a separate co-group frame (107), and wherein the first printing assembly (31a) is in the cleaning position and the second cluster is in the printing position (31b).

5. The digital printing module according to any one of the preceding claims, further comprising a cleaning device (90) provided with a movable cleaning component (91), wherein the cleaning component is configured to move on the nozzle plate of the at least one printing head and clean the nozzle plate of the at least one printing head.

6. The digital printing module according to the preceding claim, wherein: The cleaning module is located on the side of the digital printing module.

7. The digital printing module according to claim 5 or 6, wherein: The cleaning component comprises a flushing channel (92) provided with first and second elongated seals (93a, 93b), and wherein the cleaning module further comprises a cleaning liquid reservoir (95) and a liquid circulation pump (94) configured to supply and withdraw liquid from the cleaning channel.

8. The digital printing module according to any one of claims 5 to 7, wherein: The frame is connected to first and second guide rails (97a, 97b) and a displacement device (102), and wherein the displacement device is configured to displace the cleaning device under the digital printing module when a need for cleaning is detected.

9. The digital printing module according to any one of the preceding claims, wherein: A first pressure sensor (46) is located upstream of the printheads and a second pressure sensor (48) is located downstream of the printheads, and wherein a need for cleaning is identified when a resistance (Ri) on at least one printhead exceeds a resistance threshold (Rt).

10. Converting machine comprising a digital printing module according to any one of the preceding claims, wherein The converting machine is configured to receive blanks and to fold and glue the blanks to form a folding box, and wherein the converting machine includes a feeder module, a folding module, and a gluing module (14).

11. Converting machine according to the preceding claim, wherein The digital printing module is located upstream of the folding module in the conveying direction of the blank.

12. The conversion machine according to claim 10 or 11, further comprising an optical inspection module (18), wherein the optical inspection module is configured to detect the position of ink drops on the blank and determine the need to clean the at least one print head.

13. Converting machine according to the preceding claim, wherein: The optical inspection system is configured to determine an effective printing area (EF) on the blank, the effective printing area representing an area that can be printed without printing errors.

14. A conversion machine according to claim 10 or 11, wherein The control unit (82) of the inspection module is configured to propose a displacement of the printing range on the blank.

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