Printing press

Abstract

A printing machine comprising a propulsion device for propelling a material (2) in sheet form to be printed, which propulsion device is provided with at least a traction cylinder (3) which can rotate about its own axis and is designed to receive the material (2) in sheet form to be printed at an entry zone (4) and to convey it towards an exit zone (5) for the material in sheet form to exit from the traction cylinder (3), said exit zone being circumferentially spaced from the entry zone (4) along the direction of rotation of the traction cylinder (2) about its own axis. Analog printing stations (6) are arranged around the traction cylinder (3) between the entry zone (4) and the exit zone (5). The printing machine further comprises a conveying device (7) between at least two analog printing stations (6) for conveying the material (2) in sheet form to be printed which reaches from the traction cylinder (3) along a propulsion path having at least one propulsion portion (8) extending substantially straight for propelling the material (2) in sheet form to be printed, at least one digital printing station (9) being arranged along the at least one propulsion portion.

Description

Technical Field

[0001] This invention relates to a printing press. Background Technology

[0002] Known printing presses are based on different printing technologies.

[0003] Specifically, known analog printing presses are based on flexographic printing technology, which involves using flexible typographic relief plates to perform printing in sheet form on a printing substrate.

[0004] Depending on the arrangement of the printing units, a flexographic printing press can be a central roller type with printing units distributed around a single large printing roller, a "stacked" type with printing units arranged on top of each other, or a linear type with printing units distributed horizontally along the printing line.

[0005] Another type of analog printing press is based on rotary gravure printing technology, which involves directly transferring ink onto different types of printing substrates. In this type of machine, the printing units are typically arranged in a line.

[0006] Machines based on inkjet digital printing technology are also known, which allows printing directly onto a printed substrate using digital inkjet printheads arranged along a horizontal line.

[0007] In recent years, companies in the product packaging industry have become increasingly interested in digital printing technology because, unlike analog printing, it can produce small batches of prints economically and offers greater flexibility. Furthermore, it is characterized by lower costs for storing and handling materials compared to production based solely on analog printing technology.

[0008] Despite these advantages, digital printing presses also have some drawbacks, including color registration problems with stretchable substrates (such as those made of LDPE), problems during substrate travel, low solids quality, stitching defects, difficulty in fixing colors, high ownership costs, low productivity, and nozzle defects.

[0009] In order to combine the advantages of various technologies, hybrid printing presses have also been envisioned in an attempt to achieve better print quality, reduce energy consumption and waste, and ensure the repeatability of print quality over time.

[0010] This hybrid machine has both analog and digital printing stations along the path of the sheet-like material to be printed.

[0011] In the current configuration of hybrid machines, material must travel several meters between different printing stations. This introduces the risk that the tension of the sheet material to be printed may deviate or change. These factors complicate material handling and lead to increased errors in print registration.

[0012] The difficulty of print registration causes operators to spend a lot of time performing all the necessary measurements to achieve the best possible print quality. Extensive print testing means a significant waste of material.

[0013] Currently, combining various printing stations results in hybrid printing presses having a rather long longitudinal extension, thus occupying a very large area.

[0014] In addition, in order to combine the advantages of different technologies, a digital printing machine has been proposed, which is equipped with a central roller for holding the sheet material to be printed, with inkjet digital printing stations distributed around the central roller.

[0015] These machines were not entirely satisfactory either, as it was found that their print quality was lower than that of traditional digital printing presses.

[0016] In addition, these machines have unfavorable operating costs, low print coverage quality, seam defects, limited color gamut, and weak drying ability, thus limiting printing speed. Summary of the Invention

[0017] The objective of this invention is to provide a printing press that improves upon known technologies in one or more of the aforementioned aspects.

[0018] Under this objective, the purpose of the present invention is to provide a printing press that can combine high print quality with the advantages of digital printing.

[0019] Another object of the present invention is to provide a printing press that provides good control over print registration.

[0020] Another object of the present invention is to provide a printing press that occupies less space than currently known hybrid printing presses.

[0021] Another object of the present invention is to provide a printing press that can reduce waste compared to other known machines.

[0022] Another object of the present invention is to provide a flexible printing press capable of producing different types of printed designs.

[0023] Another object of the present invention is to provide a printing press capable of printing on a wide range of mutually different printed substrates.

[0024] Another object of the present invention is to provide a printing press that does not affect the printing coverage by stitching.

[0025] Another object of the present invention is to provide a printing press having a color gamut that includes all colors.

[0026] Another object of the present invention is to provide a printing press that can easily control solid colors.

[0027] Another object of the present invention is to develop a printing press that can provide better operating costs than the prior art.

[0028] Another object of the present invention is to provide a printing press that can achieve higher efficiency in ink drying compared to known technologies.

[0029] Another object of the present invention is to provide a printing press that is even capable of optimal printing on stretchable substrates such as those made of LDPE.

[0030] Another object of the present invention is to provide a printing press that can achieve printing registration over a length of several meters of a substrate to be printed.

[0031] Another object of the present invention is to provide a printing press that can operate at a higher speed than the prior art.

[0032] Another object of the present invention is to provide a printing press that, due to its technical characteristics, can open up new market segments.

[0033] Another object of the present invention is to overcome the deficiencies of the prior art in a manner that replaces any existing solutions.

[0034] Another object of the present invention is to provide a printing press that is highly reliable, relatively easy to implement, and can be produced at low cost.

[0035] This objective, as well as these and other objectives that will become more apparent below, is achieved by a printing press according to claim 1, which optionally includes the features of one or more dependent claims. Attached Figure Description

[0036] Other features and advantages of the invention will become more apparent from the description of preferred, but not exclusive, embodiments of the printing press according to the invention, which are illustrated in the accompanying drawings for non-limiting purposes, wherein:

[0037] Figure 1 This is a schematic side view of a printing press according to the present invention;

[0038] Figure 2 This is a schematic side view of a possible variation of an embodiment of the machine according to the present invention;

[0039] Figure 3 This is a partial cross-sectional view of the details of the machine according to the present invention;

[0040] Figure 4 It shows Figure 3 Variations of the detailed embodiments. Detailed Implementation

[0041] Referring to the accompanying drawings, the printing press according to the invention, generally indicated by reference numeral 1, includes a propulsion device on a support frame for propulsing a sheet-like material 2 to be printed. The propulsion device is formed of a continuous belt and has at least one traction roller 3 that is rotatable about its own axis.

[0042] Specifically, the traction roller 3 is designed to receive the sheet material 2 to be printed at the entry area 4 and convey it toward the exit area 5, which is circumferentially spaced from the entry area 4 along the rotation direction of the traction roller 3 about its own axis, and the sheet material 2 eventually leaves the traction roller 3 in the exit area.

[0043] The simulated printing station 6 is arranged around the traction roller 3 between the entry area 4 and the exit area 5.

[0044] The invention is characterized in that it includes a conveying device 7 between at least two simulated printing stations 6 for conveying a sheet-like material 2 to be printed from a traction roller 3 along a propulsion path having at least one propulsion portion 8 extending substantially straight for moving the sheet-like material 2 to be printed forward.

[0045] Also according to the invention, at least one digital printing station 9 is arranged along such a propulsion section 8.

[0046] This solution positions the digital printing station 9 within an attachment of a propulsion device for advancing or moving sheet-like material forward. This attachment extends beyond the traction roller 3, allowing the digital printing station to operate on a substantially straight propulsion section 8, thus providing an advantage in print quality. It also allows operation between two analog printing stations 6, which are arranged along the perimeter of the same traction roller, ensuring optimal print registration.

[0047] More specifically, the conveying device 7 defines at least one outward leg 10 and at least one inward leg 12 for the propulsion path of the provided sheet-like material 2. The at least one outward leg extends from the traction roller 3 to at least one redirection assembly 11 for redirecting the sheet-like material 2 to be printed. The redirection assembly is located at a position laterally spaced relative to the traction roller 3. The at least one inward leg, in turn, extends from the redirection assembly 11 to the traction roller 3.

[0048] Preferably, the propulsion portion 8 is defined along at least one outwardly extending leg 10 and advantageously extends in a substantially horizontal direction.

[0049] As shown, the conveying device 7 may include, for example, at least one redirecting roller 7a, which enables the redirection of sheet-like material 2 arriving from the traction roller 3 so as to convey it along the outwardly extending support leg 10 defined by the conveying device and then to the digital printing station 9.

[0050] Specifically, such as Figure 3 As shown, the redirecting roller 7a may be externally covered by a layer 70 of material 2 that does not adhere to the sheet form, the material of which may be made of, for example, the commercially known TEFLON trademark or other similar materials.

[0051] Alternatively, such as Figure 4 As shown, the redirecting roller 7a can also be provided by a blower rod 71, which is made of a hollow cylinder that supplies air axially under pressure and has perforated sidewalls for air outflow so as to create a gap between the outer surface of the redirecting roller 7a and the sheet-like material 2.

[0052] Optionally, such as Figure 2 In the example, the conveying device 7 may also include a bending roller 7b, which is accompanied by a sheet-like material 2 reaching from the inward support leg 12 of the conveying device, so that it adheres again to the outer surface of the traction roller 3.

[0053] Advantageously, the redirection assembly 11 may be provided by one or more redirection rollers 11a, 11b that carry the material 2 in sheet form and convey it from the outward leg 10 to the inward leg 12.

[0054] Suitably, the digital printing station 9 includes one or more digital inkjet printheads 13 arranged along the advance section 8, facing the upward surface of the sheet-like material 2 to be printed, and laterally adjacent to each other along the advance direction of the sheet-like material 2.

[0055] Optionally, a vacuum pad 16 may be provided at least along the advance portion 8, on which the sheet-like material 2 rests, which prevents unnecessary displacement of the sheet-like material 2 during ink application by the digital printing station 9.

[0056] Suitably, downstream of the digital printing station 9, there may be at least one first drying station or station 14 for initial ink drying, which may be formed, for example, by a drying channel, along the advance path defined by the conveying device 7.

[0057] Preferably, the first drying station 14 is arranged along the inward support leg 12 of the conveying device 7, and the conveying device 7 returns the material to be printed 2 to the transfer roller 3.

[0058] More preferably, according to the illustrated embodiment, there is at least one substantially straight first propulsion portion 8a along the outwardly extending support leg 10 defined by the conveying device 7, and at least one substantially straight second propulsion portion 8b along the inwardly extending support leg 12. In this case, the digital printing station 9 is suitably arranged along the aforementioned first propulsion portion 8a, and the first drying station 14 is arranged along the second propulsion portion 8b.

[0059] It should be noted that there may be one or more simulated printing stations 6 upstream and downstream of the conveyor 7, relative to the direction in which the traction roller 3 rotates about its own axis.

[0060] Suitably, the simulated printing station 6 arranged around the traction roller 3 may include at least one flexographic printing station and / or at least one rotary gravure printing station and / or at least one “offset” type printing station.

[0061] Advantageously, the rotary gravure printing station can be arranged, for example, directly upstream of the exit area 5 of the sheet-like material 2 exiting from the traction roller 3, preferably providing separation of the sheet-like material 2 to be printed from the traction roller 3, so as to allow the sheet-like material 2 to pass between the rollers of the rotary gravure printing station, such as... Figure 1 and Figure 2 As shown.

[0062] Advantageously, the simulated printing station 6 may also include at least one station for pretreating the sheet-like material to be printed by applying at least one layer, the simulated printing station being arranged upstream of the conveyor 7 along the direction of rotation of the traction roller 3 about its axis of rotation. For example, such pretreatment layer may be a primer or coating adapted to improve the adhesion of ink to the sheet-like material 2 to be applied by the digital printing station and / or the subsequent simulated printing station 6.

[0063] It should be noted that the inks used in the analog printing station 6 and the digital printing station 9 can be water-based, biological, or solvent-free.

[0064] Advantageously, along the feeding device of the sheet-like material 2, preferably downstream of the exit area 5 of the sheet-like material 2 from the transfer roller 3, there may be at least one second drying station or station 15 for the final drying of the ink, which may also be provided by the drying channel.

[0065] It should be noted that, optionally, at least one corresponding shroud 18 for drying ink may be provided around the traction roller 3 and downstream of each simulated printing station 6, preferably between one simulated printing station 6 and a subsequent simulated printing station, in the direction of rotation of the traction roller 3. It should also be noted that at least one drying shroud 18 may also be provided downstream of the conveying device 7.

[0066] According to the present invention, the printing press is operated as follows.

[0067] The sheet material 2 to be printed is fed to the traction roller 3 by the feeding device through the entry area 4, and passes through at least one simulated printing station 6 while adhering to the outer surface of the transfer roller 3. The simulated printing station may suitably apply at least one layer of pretreatment to the sheet material 2 conveyed on the transfer roller 3, or generally perform simulated printing, such as flexographic printing or rotary gravure printing.

[0068] Subsequently, the sheet-like material 2 is picked up from the transfer roller 3 by the conveying device 7 via the redirection roller 7a, so as to be conveyed along the outward support leg 10 along the advance path defined by the conveying device 7, so as to be sent to the digital printing station 9 arranged outside the transfer roller 3.

[0069] Specifically, the sheet-like material 2 travels along the outward-facing support leg 10 on the first propulsion section 8a, passing through the digital printing station 9, where the digital printing process is performed.

[0070] Once the sheet material 2 leaves the digital printing station 9, it reaches the redirection assembly 11, which guides it toward the inward support leg 12, where it travels on the second forward section 8b and through the first drying station 14, which allows for initial drying of the ink applied to the sheet material to be printed.

[0071] Downstream of the drying station 14, the sheet-like material 2 then reaches the traction roller 3 again to continue being pushed forward, while adhering to the outer surface of the traction roller 3.

[0072] At this time, as the sheet-like material 2 advances on the traction roller 3, it passes through the simulated printing station 6 located downstream of the conveying device 7, where each simulated printing station applies ink of the corresponding color to the sheet-like material 2.

[0073] Once it reaches the exit zone 5, the sheet material 2 is finally removed from the traction roller 3 and sent to the second drying station 15, which performs final drying of the ink applied to the sheet material 2 during its advance from the entry zone 4 of the traction roller 3 to the exit zone 5.

[0074] In practice, it has been found that the present invention, by providing a printing press, fully achieves the intended goals and objectives. Compared with conventional hybrid printing presses, this printing press is very compact due to the presence of the traction roller, and it can ensure the best quality of digital printing by means of the presence of a conveying device inserted between the entry and exit areas of the traction roller for sheet-like material. This enables digital printing to be performed on the substantially straight feed portion of the sheet-like material.

[0075] Another advantage of the present invention is that, compared to conventional hybrid machines, it ensures optimal print registration due to the presence of simulated printing stations arranged sequentially around the traction roller.

[0076] Furthermore, the advantage of having an analog printing station downstream of a digital printing station is that it is possible to apply very thick layers of ink, paint, or adhesive (cold seal, heat seal, etc.) at high speeds, which is more difficult to achieve with digital technology, where the ink, paint, or adhesive needs to be applied at very low viscosity and requires a very long drying oven to achieve the same speed as this invention.

[0077] Another advantage of having analog printing stations downstream of digital printing stations is the uniformity and chromaticity of solid colors, because they can be printed in a single printing station using analog technology, unlike digital technology which uses multiple heads to overlay multiple colors to achieve spot colors, thus reducing the time and cost of color matching.

[0078] This invention, conceived in this way, is susceptible to many modifications and variations, all of which fall within the scope of the appended claims.

[0079] Therefore, for example, digital printing station 9 can be implemented using equipment that uses toners or inkjet technology.

[0080] It should also be noted that if EB / UV inks are used, the drying station or multiple drying stations will be suitable for using electron beam or ultraviolet emission to polymerize the ink, depending on the type of ink.

[0081] In practice, the materials used, as well as the possible shapes and sizes, can be any that meet the requirements and existing technology.

Claims

1. A printing press comprising a feeding device for advancing a sheet of material (2) to be printed, the feeding device having at least a traction roller (3) rotatable about its own axis and designed to receive the sheet of material (2) to be printed at an entry area (4) and convey it toward an exit area (5) so that the sheet of material leaves the traction roller (3), the exit area being circumferentially spaced from the entry area (4) along the direction of rotation of the traction roller (3) about its own axis, and simulated printing stations (6) arranged around the traction roller (3) between the entry area (4) and the exit area (5), the printing press being characterized in that it further comprises a conveying device between at least two of the simulated printing stations (6). (7) for conveying the sheet material (2) to be printed from the traction roller (3) along a propulsion path, the propulsion path having at least one propulsion section (8) extending substantially straight for propulsing the sheet material (2) to be printed, at least one digital printing station (9) arranged along the at least one propulsion section (8), the conveying device (7) defining at least one outward leg (10) and at least one inward leg (12) for the propulsion path, the at least one outward leg extending from the traction roller (3) to at least one redirection assembly (11) for redirecting the sheet material (2) to be printed, the at least one inward leg extending from the redirection assembly (11) to the traction roller (3).

2. The printing press according to claim 1, characterized in that, The at least one propulsion portion (8), which extends substantially straight, is defined along the at least one outwardly extending support leg (10).

3. The printing press according to claim 1, characterized in that, The at least one propulsion portion (8), which extends substantially straight, extends in a substantially horizontal direction.

4. The printing press according to claim 1, characterized in that, The digital printing station (9) includes at least one inkjet digital printing head (13) along the at least one advance portion (8), the inkjet digital printing head facing the upward side of the sheet-like material (2) to be printed.

5. The printing press according to claim 1, characterized in that, It includes at least one first drying station (14) downstream of the at least one digital printing station (9) along the advance path.

6. The printing press according to claim 5, characterized in that, The at least one first drying station (14) is arranged along the at least one inwardly extending support leg (12).

7. The printing press according to claim 5, characterized in that, Along the at least one outward support leg (10), there is at least one first propulsion portion (8a) extending substantially straight, and along the at least one inward support leg (12), there is at least one second propulsion portion (8b) extending substantially straight, the at least one digital printing station (9) is arranged along the at least one first propulsion portion (8a), and the at least one first drying station (14) is arranged along the at least one second propulsion portion (8b).

8. The printing press according to claim 1, characterized in that, The simulated printing station (6) includes at least one flexographic printing station.

9. The printing press according to claim 1, characterized in that, The simulated printing station (6) includes at least one rotary gravure printing station.

10. The printing press according to claim 1, characterized in that, The simulated printing station (6) includes at least one offset printing station.

11. The printing press according to claim 1, characterized in that, The simulated printing station (6) includes at least one station for applying at least one layer to pre-treat the sheet-like material to be printed, and the simulated printing station is arranged upstream of the conveying device (7) in the direction of rotation of the traction roller (3) about its axis of rotation.

12. The printing press according to claim 5, characterized in that, It includes at least one second drying station (15), which is arranged downstream of the departure area (5) along the propulsion device.

13. A printing process, characterized in that, It sequentially includes the following steps: feeding the sheet-like material (2) to be printed through the entry area (4) to the traction roller (3); advancing the sheet-like material (2) adhered to the outer surface of the traction roller (3); performing at least one simulated printing on the sheet-like material to be printed adhered to the traction roller (3); turning the sheet-like material (2) to be printed from the traction roller (3) so as to convey it along a propulsion path having at least one propulsion portion (8) extending substantially straight; and printing the sheet-like material (2) to be printed. At least one digital printing is performed on the material (2) while it travels along the at least one advance section (8) which is substantially straight; the sheet-like material (2) to be printed is returned to adhere to the outer surface of the traction roller (3); the sheet-like material (2) to be printed is advanced to the traction roller (3); at least one analog printing is performed on the sheet-like material (2) to be printed adhered to the traction roller (3); the printed sheet-like material (2) is picked up from the traction roller by leaving the area (5).

14. The printing process according to claim 13, characterized in that, Before the step of redirecting the sheet-like material (2) from the traction roller (3), at least one simulated printing step is performed, including applying at least one pretreatment layer to the sheet-like material to be printed.

15. The printing process according to claim 13, characterized in that, After performing at least one digital printing step, and before the step of returning the sheet-like material (2) to be printed to adhere to the outer surface of the traction roller (3), at least one initial drying step of the ink is provided.

16. The printing process according to claim 13, characterized in that, After the step of picking up the sheet-like material (2) from the traction roller (3) through the exit area (5), at least one final drying step of the ink is provided.

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