PRINTING MACHINE FOR PRINTING A LAMINAR WEB

Abstract

Printing machine, for printing a laminar web, comprising a feeding unit (10) defining a printing area (A); an inkjet printing station (20) comprising a plurality of inkjet printing modules (21) slidably arranged along a transverse guide (22); a positioning device (30) adapted to precisely slide the inkjet printing modules (21) along the transverse guide (22); wherein each inkjet printing module (21) includes a first coupling (31) and is independent from other inkjet printing modules (21) allowing an independent movement of each inkjet printing module (21) along the transverse guide (22); and the positioning device (30) includes a second coupling (32) complementary to each first coupling (31), the second coupling (32) being releasably engageable to each first coupling (31) in an automatic manner, the positioning device (30) being configured to precisely slide each inkjet printing module (21) engaged thereto, along the transverse guide (22).

Claims

1. Printing machine for printing a laminar web, the printing machine comprising: rollers defining a web path for guiding a web, the rollers comprising first and second supporting rollers defining therebetween a printing area of the web path, a pulling device being adapted to maintain a constant tension in the web guided through the printing area; an inkjet printing station comprising a plurality of inkjet printing modules with inkjet print heads facing the printing area of the web path for printing thereon, the inkjet printing modules being slidably arranged along a transverse guide transverse to the web path, each inkjet printing module being adapted for printing a fraction of the width of the printing area with digitally modifiable items; a positioning device adapted to precisely slide the inkjet printing modules along the transverse guide in the direction transversal to the web path; and each inkjet printing module includes a first coupling and is independent from other inkjet printing modules allowing an independent movement of each inkjet printing module along the transverse guide, the positioning device including a second coupling complementary to each first coupling, the second coupling being releasably engageable to each first coupling in an automatic manner by an engagement driver, the positioning device being configured to precisely slide each inkjet printing module engaged thereto, through the engaged first and second couplings, along the transverse guide.

2. The printing machine according to claim 1, wherein each inkjet printing module includes a braking device automatically movable between a braked position, where the braking device prevents the sliding movement of the inkjet printing module along the transverse guide, and an unbraked position where allows the sliding movement of the inkjet printing module along the transverse guide.

3. The printing machine according to claim 2, wherein on each inkjet printing module the first coupling and the braking device are linked to each other, determining an automatic movement of the braking device to the unbraked position when the first coupling is engaged to the second coupling and determining the return of the braking device to the braked position when the first coupling is disengaged from the second coupling.

4. The printing machine according to claim 1, wherein each inkjet printing module includes a spacer device configured to move at least the inkjet print heads thereof in a spacing direction perpendicular to the transverse direction, without changing the position of the inkjet printing module in the transverse direction, between a printing position adjacent to the printing area and a storage position spaced apart from the printing area.

5. The printing machine according to claim 4, wherein each inkjet printing module includes attached thereto a capping system configured to automatically cover the corresponding inkjet printing heads with a cap when in the storage position; and/or the machine includes a web thickening awareness signal emitter upstream of the inkjet printing station configured to detect a splice in the web, the spacer devices of all the inkjet printing modules being configured to move at least the inkjet print heads thereof to the storage position in response to a splice detection obtained from the web thickening awareness signal emitter.

6. The printing machine according to claim 1, wherein the printing machine further includes an ink curing/drying station comprising a plurality of independently movable curer/dryer modules slidably connected to a curer/dryer transverse guide, transverse to the web path, to emit a curer/dryer at different regions of the web, by at least one curer/dryer emitter included in each curer/dryer module facing the web path, to cure/dry ink printed on the web by the inkjet printing modules, each curer/dryer module includes a third coupling, and the positioning device, or an additional positioning device adapted to precisely slide the curer/dryer modules along the curer/dryer transverse guide in the transverse direction, includes a fourth coupling complementary to the third couplings, the fourth coupling being releasably engageable to each third coupling in an automatic manner by an engagement driver, the positioning device, or the additional positioning device, being adapted to precisely slide each curer/dryer module engaged thereto, through the engaged third and fourth couplings, in the transverse direction.

7. The printing machine according to claim 1, wherein the printing machine further includes an ink curing/drying station comprising a plurality of independently movable curer/dryer modules, facing the web path and slidably connected to a curer/dryer transverse guide transverse to the web path, to emit a dryer at different regions thereof to dry ink printed on the web by the inkjet printing modules, each curer/dryer module is linked to one inkjet printing module determining a simultaneous movement in the transverse direction of the curer/dryer module and the inkjet print heat linked together.

8. The printing machine according to claim 6, wherein the curer/dryer module is a UV light emitter, an infrared light emitter, or a hot air blower.

9. The printing machine according to claim 7, wherein the curer/dryer module is a UV light emitter, an infrared light emitter, or a hot air blower.

10. The printing machine according to claim 1, wherein each inkjet printing module carries a decentralized ink storage attached thereto, or some inkjet printing modules carries a decentralized ink storage attached thereto and each of the remaining inkjet printing modules is connected through a pipe to one of those ink storages, and each decentralized ink storage is connected to a centralized ink storage through a pipe and is configured to regulate the ink pressure feed to the inkjet printing modules.

11. The printing machine according claim 1, wherein the pulling device includes synchronized processing advancing motors connected to the first and second supporting rollers to produce a unison actuation thereof in coordination with the operation of the rest of the pulling unit.

12. The printing machine according to claim 11, wherein a first tension sensor is arranged for measuring the tension of the film web upstream of the main pulling unit and downstream of the inkjet printing modules, and an electronic control device controls the operation of the processing advancing motor based on a control signal received from the first tension sensor.

13. The printing machine according to claim 1, wherein the printing machine further includes a flexographic, offset or rotogravure printing device associated with an additional printing area of the web path to print non digitally modifiable on a web guided through the web path.

14. The printing machine according to claim 1, wherein an optical sensor faces the web path and is associated with a control unit adapted to analyze data provided by the optical sensor, determine the position of the non-digitally modifiable items printed on the web guided through the web path, and automatically adjust the inkjet printing modules for precisely positioning the digitally modifiable items to be printed in the web in regard to the position of the non-digitally modifiable items.

15. The printing machine according to claim 1, wherein the positioning device and/or each individual inkjet printing module includes a position detector adapted for determining the real position of each inkjet printing module in the transverse direction, and a control device is adapted for controlling the actuation of the positioning device in response to the measurements of the position detector.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0067] The foregoing and other advantages and features will be more fully understood from the following detailed description of an embodiment with reference to the accompanying drawings, to be taken in an illustrative and non-limitative manner, in which:

[0068] FIG. 1 shows a transverse section of the printing machine according to one embodiment, with one inkjet printing module in the printing position;

[0069] FIG. 2 shows the same zoom view as FIG. 1, but with the inkjet printing module in the storage position;

[0070] FIG. 3 shows the same view as FIG. 1 but according to an alternative embodiment wherein the positioning device can engage with both the inkjet printing modules and the curing/drying modules;

[0071] FIG. 4 shows a plan view of the printing area of the printing machine shown in FIGS. 1, 2 and 3, with the inkjet printing station including six inkjet printing modules in different transverse positions, the printing area including several digitally modifiable items, shown as bar codes, printed therein;

[0072] FIG. 5 shows the same view as FIG. 4 but according to an alternative embodiment of the positioning device.

DETAILED DESCRIPTION OF AN EMBODIMENT

[0073] The foregoing and other advantages and features will be more fully understood from the following detailed description of an embodiment with reference to the accompanying drawings, to be taken in an illustrative and not limitative.

[0074] According to a preferred embodiment of the present invention, the printing machine includes a feeding unit 10 with multiple rollers 12 for guiding a flexible web through a web path between an unwinding reel and a rewinding reel.

[0075] Two of said rollers 12 are a first supporting roller 12a and a second supporting roller 12b which define, in between, a flat printing area A of the web tensioned between the first and second supporting rollers 12a, 12b.

[0076] According to the present embodiment, each of the first and second supporting rollers 12a, 12b, is actuated by one processing advancing motors, being both synchronized to precise control the tension of the flexible web between said first and second supporting rollers 12a and 12b, said actuation being in coordination with the rest of the pulling unit which moves the flexible web in the conveying direction along the web path.

[0077] The printing machine further comprises a transverse bridge or beam, perpendicular to the conveying direction, supporting an inkjet printing station 20 above the printing area A.

[0078] The inkjet printing station includes, for example, two parallel horizontal transverse guides 22 transverse to the web path attached to said transverse bridge or beam.

[0079] The inkjet printing station 20 further comprises multiple inkjet printing modules 21, each inkjet printing module 21 including, in a removable and disposable unit, inkjet print heads configured to eject ink droplets against a portion of the width of the printing area A in precise positions, each inkjet printing module 21 being able to print a fringe on the flexible web.

[0080] Each inkjet printing module 21 is slidably attached to said two parallel transverse guides 22 through carriages, allowing for a movement thereof in the transverse direction, parallel to the web of the printing area A, each inkjet printing module 21 being positionable in any transverse position above the printing area A for printing a fringe thereon.

[0081] Each inkjet printing module 21 also includes spacer device 50 comprising a vertical track placed between the inkjet print heads and the corresponding carriages, permitting the vertical movement of the inkjet print heads between a printing position, where the inkjet print heads are close to the printing area A and can print thereon, as shown in FIG. 1, and a storage position where the inkjet print heads are spaced apart from the printing area A, as shown in FIG. 2, said distance being too wide for allowing a precise printing.

[0082] Each spacer device 50 further includes an actuator integrated in the inkjet printing module 21 adapted for moving the inkjet print heads of one inkjet printing module 21 between the printing position and the storage position along the vertical track, said movement being independent from the movement of the inkjet print heads from other inkjet printing modules 21.

[0083] Each inkjet printing module 21 also includes a capping system 23 comprising a cap intended for covering the printing inkjet print heads of the inkjet printing module 21 preventing its drying, and an actuator device intended for moving said cap between a capping position, where the cap covers the inkjet print heads, and a printing position where the cap is away from the inkjet print heads and not interferes with the web path when the inkjet printing module 21 is in the printing position.

[0084] In this embodiment, the cap is pivotally attached to the inkjet printing module 21, but an alternative embodiment in which the cap is slidably attached thereto is also possible.

[0085] When an inkjet printing module 21 is in the printing position the cap shall be in the printing position, as seen in FIG. 1. But when an inkjet printing module 21 is in the storage position, the capping device 23 can be actuated to place the cap in the capping position, as shown in FIG. 2.

[0086] According to one embodiment of the present invention, each inkjet printing module 21 includes a decentralized ink storage adapted to regulate the pressure of the ink to be provided to the inkjet print heads of said inkjet printing module 21.

[0087] Alternatively, only some of the inkjet printing modules 21 include a decentralized ink storage, for example only alterne inkjet printing modules 21, or one of every three inkjet printing modules 21, and each of the remaining inkjet printing modules 21 are connected to a decentralized ink storage of an adjacent inkjet printing module 21 through a flexible pipe allowing for an independent movement between the connected inkjet printing modules 21.

[0088] Each decentralized ink storage is connected through flexible pipes to a centralized ink storage 70, where the ink is stored and from where the ink is distributed to the decentralized ink storages.

[0089] The printing machine further comprises a positioning device 30 intended for its coupling to each single inkjet printing module 21 and for dragging said inkjet printing module 21 along the transverse guide 22.

[0090] Each inkjet printing module 21 includes a first coupling 31, and the positioning device 30 includes a second coupling 32 complementary to the first coupling 31.

[0091] The second coupling 32, or each of the first couplings 31, is actuated by an engagement driver which produces the automatic coupling and uncoupling between the first and second couplings 31, 32, when in a suitable position.

[0092] In the example shown in FIGS. 1, 2, 3 and 4 the first coupling 31 is defined by a hole perpendicular to the transverse direction, and the second coupling 32 is defined by an actuated plunger which, when extended, can be inserted in one of said holes and when retracted does not interfere with none of said holes, being said actuated plunger connected to a carriage movable in the transverse direction to align the actuated plunger with different of said holes.

[0093] In the example shown in FIG. 5, the second coupling configuration 32 is a threaded shaft parallel to the transverse guides 22, and each inkjet print module 21 include one first coupling configuration 31 comprising one

[0094] According to a first embodiment, the positioning device 30 is a carriage slidably attached to a positioning transverse guide parallel to the transverse guides 22 of the inkjet printing station 20 and actuated by a driving unit which produces the movement of the carriage in the transverse direction, positioning the second coupling 32 adjacent to one first coupling 31 of one inkjet printing module 21, enabling the coupling thereof and the drag of the inkjet printing module 21 coupled to the positioning device 30.

[0095] According to an alternative embodiment, the positioning device is a threaded shaft parallel to the transverse guides 22 which rotates along its axis by an actuator. Said threaded shaft constitutes the second coupling 32, where each of the first coupling 31 can be engaged independently by a corresponding engaging drive. When a first coupling 31 is engaged with the threaded shaft, the rotation of the threaded shaft produces the movement of the engaged inkjet printing module 21 in the transverse direction.

[0096] According to an alternative embodiment, the printing machine further comprises an ink curing/drying station 40 which comprises a plurality of curer/dryer modules 41, such UV emitters, infrared emitters, or air blowers.

[0097] Each curer/dryer module 41 will affect a portion of the width of the web path equivalent to the width of one fringe printable by one inkjet printing module 21.

[0098] Each curer/dryer module 41 is slidably attached to a curer/dryer transverse guide 42 allowing its individual movement in the transverse direction.

[0099] According to one embodiment, each curer/dryer module 41 includes a third coupling 33 complementary to a fourth coupling 34 included in the positioning device 30 or included in an additional positioning device 30′ equivalent to the positioning device 30 described above.

[0100] The coupling and uncoupling between the third and fourth couplings 33, 34 is produced by an engagement driver when in a suitable position.

[0101] Alternatively, each curer/dryer module 41 is directly connected to one inkjet printing module 21 for its simultaneously movement.

[0102] It will be understood that various parts of one embodiment of the invention can be freely combined with parts described in other embodiments, even being said combination not explicitly described, provided that such combination is within the scope of the claims and that there is no harm in such combination.