Overprinting system and method for producing three-dimensional reliefs on a flexible support

Abstract

An overprinting system and method for producing three-dimensional reliefs on a flexible support are described. The overprinting system 10 comprises a flexible support 2 in which preset zones to be overprinted are present, and at least one printing assembly 20. The printing assembly 20 comprises a first rotatable roller or cylinder 4, operating as a plate-holder roller, having on its surface a printing plate with a "male"-type raised profile, corresponding to the relief which is intended to be overprinted, and further comprises a second rotatable roller or cylinder 3, operating as a contrast roller, adapted to memorise on its own surface, when placed in a condition of mutual pressure with the first roller or cylinder 4 under operating conditions of the overprinting system, a "female"-type contrast profile, corresponding and complementary to said "male"-type profile. The combined action of said "male"-type raised profile and "female"-type contrast profile results in the transfer of the relief which is intended to be overprinted onto the flexible support 2 to be overprinted, when said flexible support 2 passes between the first roller or cylinder 4 and the second roller or cylinder 3. The overprinting system 10 further comprises actuation means 7 and control means 5, 9. The actuation means 7 are configured to command, in a controllable manner, the rotation of the first roller or cylinder 4 and the advancement of the flexible support 2 along an unwinding path, upstream of the printing assembly 20 in the unwinding direction and passing through said printing assembly 20. The control means 5, 9 are configured to control the actuation means 7, so as to coordinate the rotation of the first roller or cylinder 4 and the advancement of the flexible support 2, to determine a correspondence of the preset zones to be overprinted of the flexible support 4 with said printing plate of the first roller or cylinder 4 and respective "male"-type raised profile, and with the complementary "female"-type contrast profile of the second roller or cylinder 3, so as to imprint the relief which is intended to be overprinted on the preset zones to be overprinted of the flexible support 2 as they pass and are pressed between the first roller or cylinder 4 and the second roller or cylinder 3.

Description

[0001] OVERPRINTING SYSTEM AND METHOD FOR PRODUCING THREE-DIMENSIONAL RELIEFS ON A FLEXIBLE SUPPORT

[0002] DESCRIPTION

[0003] TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0004] Field of application.

[0005] The present invention pertains to the technical field of overprinting on flexible supports. In particular, the invention relates to a system and a corresponding overprinting method for producing three-dimensional reliefs on a flexible support.

[0006] As a typical example of application, provided by way of example and not limitation, the invention relates to a solution suitable for performing overprinting of relief Braille characters.

[0007] Description of the prior art.

[0008] In the technical field of so-called “overprinting,” the possibility of overprinting new characters or figures or colours or other graphic signs on labels or packages or other supports is known. Such overprinting may be useful, for example, to allow recycling and / or reuse of already printed labels or packages, creating new ones on the same support.

[0009] Various solutions are known for overprinting two-dimensional characters or graphic signs.

[0010] Recently, significant needs have arisen for the possibility of overprinting three-dimensional characters and / or graphic signs, combining the advantages of overprinting (for example, effective reuse of already used supports) and three-dimensional printing (for example, to produce labels with three-dimensional effects, of greater impact and effectiveness, to print three-dimensional data on legal labels, and so on).

[0011] One area where this need is particularly felt, being tied to an essential requirement, is the creation of writings in Braille alphabet on product labels intended for the blind.

[0012] Known solutions capable of performing two-dimensional overprinting cannot provide three-dimensional overprinting of acceptable quality.

[0013] Moreover, although methods and systems for three-dimensional overprinting exist, they provide results that are not entirely satisfactory.

[0014] Therefore, the need to improve the quality of overprinting of three-dimensional characters or graphic signs on flexible materials in reels, already printed, is strongly felt and currently lacks fully satisfactory solutions.

[0015] SUMMARY OF THE INVENTION.

[0016] The object of the present invention is to provide an overprinting system for producing three-dimensional reliefs on a flexible support, which allows overcoming at least partially the drawbacks mentioned above with reference to the known art, and to meet the aforementioned needs particularly felt in the relevant technical field. This object is achieved by a system for overprinting on flexible supports in accordance to claim 1.

[0017] Further embodiments of such system are defined in claims 2 to 16.

[0018] An overprinting method employing the aforementioned system according to the invention is defined in claim 17.

[0019] A further embodiment of such method is defined in claim 18.

[0020] BRIEF DESCRIPTION OF THE DRAWINGS.

[0021] Further features and advantages of the overprinting system and method, according to the invention, will emerge from the following description of preferred embodiments, given by way of indication and not limitation, with reference to the attached figure:

[0022] - Figure 1 illustrates a simplified block diagram of an overprinting system, according to an embodiment of the present invention;

[0023] - Figure 2 illustrates an example of a printing plate, arranged on a plate-holder roller, according to an embodiment of the overprinting system according to the present invention;

[0024] - Figure 3 illustrates an example of a package with a raised overprint made using the plate-holder roller and the printing plate of figure 2.

[0025] DETAILED DESCRIPTION.

[0026] An system for overprinting on flexible supports, according to various embodiments included in the invention, will be described in more detail below, with reference to figure 1.

[0027] The overprinting system 10 for producing three-dimensional reliefs on a flexible support comprises first a flexible support 2, wherein preset zones to be overprinted are present, and at least one printing assembly 20.

[0028] The at least one printing assembly 20, in turn, comprises at least one first rotatable roller or cylinder 4, operating as a plate-holder roller, having on its surface a printing plate with a raised profile of the “male” type, corresponding to the relief which is intended to be overprinted, and further comprises at least one second rotatable roller or cylinder 3, operating as a contrast roller, adapted to memorise on its own surface, when placed in a condition of mutual pressure with the first roller or cylinder 4 under operating conditions of the overprinting system, a contrast profile of the “female” type, corresponding and complementary to said “male”-type profile.

[0029] The combined action of said “male”-type raised profile and “female”-type contrast profile results in the transfer of the relief which is intended to be overprinted to the flexible support 2 to be overprinted, when such flexible support 2 passes between the first roller or cylinder 4 and the second roller or cylinder 3.

[0030] The overprinting system 10 further comprises actuation means 7 and control means 5, 9.

[0031] The actuation means 7 are configured to command, in a controllable manner, the rotation of the first roller or cylinder 4 and the advancement of the flexible support 2 along an unwinding path, upstream of the printing assembly 20 in the unwinding direction and passing through said printing assembly 20.

[0032] The control means 5, 9 are configured to control the actuation means 7, so as to coordinate the rotation of the first roller or cylinder 4 and the advancement of the flexible support 2, to determine a correspondence of the preset zones to be overprinted of the flexible support 4 with said printing plate of the first roller or cylinder 4 and respective “male”-type raised profile, and with the complementary “female”-type contrast profile of the second roller or cylinder 3, so as to imprint the relief which is intended to be overprinted on the preset zones to be overprinted of the flexible support 2 as they pass and are pressed between the first roller or cylinder 4 and the second roller or cylinder 3.

[0033] As auxiliary information to better understand the invention, it should be noted that the flexible support 2 may be any flexible support, for example paper-based or multilayer, suitable for printing, which can be wound or be windable into a reel.

[0034] In a preferred application context, such support is a previously printed support, on which overprinting is to be carried out; however, the system of the invention can operate in the same way for a first print on a new support: even in this case, the accurate control of the printing zones ensured by the system of the present invention, in the manner described herein, may be useful.

[0035] Preferably, the flexible support 2 is in the form of a strip which, for example, develops continuously in a first direction and has, in a second direction orthogonal to the first, a width equal to the width of the unwinding and rewinding reels. Along its continuous development in the first direction, the flexible support has a succession of zones corresponding to respective labels or packages to be printed or overprinted in series, in the same manner.

[0036] It should be noted, however, that the system according to the invention can operate on flexible supports having geometries and configurations different from those illustrated above.

[0037] According to an embodiment, the overprinting system 10 is configured to operate on a reel 1 comprising a flexible ribbon-like strip.

[0038] According to an embodiment, the overprinting system 10 is configured to operate on a reel 1 comprising a plurality of envelopes or bags in sequence.

[0039] According to an embodiment, the overprinting system 10 is configured to operate on a reel 1 pre-printed with a smooth surface or is neutral.

[0040] In accordance with an embodiment, the overprinting system 10 is configured to provide, as a result of the overprinting, a plurality of packages and / or bags and / or envelopes with raised printing, deriving from said flexible support. In accordance with an embodiment, the overprinting system 10 is configured to provide, as a result of the overprinting, a reel of relief-overprinted flexible support. In this case, the overprinting system 10 comprises a second rewinding reel of said flexible support 2, once it has been relief printed.

[0041] According to an implementation option, the overprinting system 10 further comprises a plurality of return rollers configured to arrange said unwinding path for the flexible support 2; in this case, the unwinding path is enclosed between said first reel and said second reel.

[0042] In accordance with an embodiment, the overprinting system 10 further comprises heat treatment means configured to heat in a controllable manner one side, or the other side, or both sides of the flexible support 2 and / or of the respective zones to be overprinted, to facilitate the overprinting of the relief on the zones to be overprinted of the flexible support.

[0043] According to an implementation option of said embodiment, the aforesaid heat treatment means comprise an electrical resistor arranged in the first roller or cylinder 4 and / or a hot air generator 6.

[0044] The electrical resistor arranged in the first roller or cylinder 4 is adapted to function as a calender, that is, it is configured to heat in a controllable manner the side of the flexible support, referred to as the inner side, facing the first roller or cylinder 4, while it transits in contact with the first roller or cylinder 4.

[0045] The hot air generator 6 is configured to heat in a controllable manner the other side of the flexible support, referred to as the outer side, facing the second roller or cylinder 3, while it transits close to, upstream, and / or in contact with the second roller or cylinder 3.

[0046] According to various possible implementation options of the overprinting system 10, the control means are configured to operate in any of the following modes, at the passage of the flexible support 2 between the first roller or cylinder 4 and the second roller or cylinder 3, and thus during the overprinting action:

[0047] - actuating only said electrical resistor, or

[0048] - actuating only said hot air generator, or

[0049] - actuating both said electrical resistor and said hot air generator, or

[0050] - actuating neither the electrical resistor nor the hot air generator.

[0051] The operating mode is determined as a function of the type of flexible support to be overprinted.

[0052] According to an implementation option of the overprinting system 10, said three- dimensional reliefs correspond to writings in Braille alphabet.

[0053] According to another implementation option of the overprinting system 10, said three- dimensional reliefs correspond to one or more raised marks and / or logos and / or inscriptions and / or drawings and / or figures.

[0054] Hereinafter, details and implementation examples of the components of the overprinting system 10, already mentioned above, are provided.

[0055] According to an embodiment of the overprinting system 10, the actuation means 7 of the printing assembly comprise an actuator of the “brushless motor” type.

[0056] According to other possible embodiments, the actuation means 7 comprise other types of motors / actuators known per se.

[0057] According to an embodiment, the overprinting system 10 further comprises a reel 1 of flexible support 2, that is, in other words, said flexible support comprises a reel 1.

[0058] In this case, the actuation means 7 are configured to command in a controllable manner the advancement of the flexible support 2 by means of a control of the unwinding rotation of said reel 1.

[0059] The advancement of the flexible support 2, in different implementation options, is continuous or intermittent.

[0060] In accordance with an embodiment of the overprinting system 10, the control means 5, 9 comprise:

[0061] - a detection device 5 configured to detect the advancement of the flexible support and / or an offset between preset zones to be overprinted of the flexible support 2 and respective printing zones of the first roller or cylinder 4;

[0062] - a processing unit 9, operatively connected to said detection device 5 to receive signals indicative of the advancement of the flexible support and / or said offset, and configured to determine control signals for the actuation means 7, based on said received signals.

[0063] In said embodiment, the actuation means 7 are operatively connected to said processing unit 9 to receive said control signals.

[0064] According to an implementation option, the flexible support 2 comprises recognition markings, or notches, adapted to signal a cut pitch and / or preset zones to be overprinted.

[0065] In this case, said detection device 5 comprises a reading head 5 or photocell 5, arranged along the unwinding path, configured to read said recognition markings or notches.

[0066] According to possible implementation options, the processing unit 9 comprises, or consists of, one or more electronic processors or computers.

[0067] In accordance with an embodiment, the overprinting system 10 further comprises means for shifting and / or controlling the position of the first roller or cylinder 4, in a transverse direction and / or in a perpendicular direction with respect to the movement direction of the flexible support 2 upon the passage between the first and second rollers or cylinders.

[0068] In accordance with an implementation option, said means for shifting and / or controlling the position comprise a device configured to control the position of the first roller or cylinder 4 in a direction perpendicular to the movement direction of the flexible support 2.

[0069] According to an implementation option, said device is controlled by the control means 9 to automatically control the position of the first roller or cylinder 4 in a direction perpendicular to the movement direction of the flexible support 2 and / or configured to adjust the mutual position between the first roller or cylinder 4 and the second roller or cylinder 3, during the relief overprinting action.

[0070] According to an embodiment of the overprinting system 10, said second roller or cylinder 3 is configured to be freely rotatable (i.e. , “idle”). In this case, the rotation of the second roller or cylinder 3 is commanded, under operating conditions, by the controlled rotation of the first roller or cylinder 4, by contact and / or friction, under operating conditions in which the first roller or cylinder 4 is brought into contact with the second roller or cylinder 3, applying a controlled pressure thereto.

[0071] Thus, according to an implementation option of said embodiment, the overprinting system is configured to operate as follows:

[0072] - the control means 9 control the rotation of the first roller or cylinder 4, and further control, by means of the position control device, the position of the first roller or cylinder 4 in a direction perpendicular to the movement direction of the flexible support 2, so that it comes into contact, by applying a predefined and adjusted pressure, with the second roller or cylinder 3, at least when the flexible support 2 passes between said two rollers or cylinders.

[0073] The contact and pressure between the two rollers or cylinders determine several consequences:

[0074] - first of all, they cause the second roller or cylinder 3 to rotate in a coordinated manner with the first roller or cylinder 4 (the coordination of the rotations is obtained automatically due to the fact that the second roller or cylinder 3 rotates as a result of the rotation of the first roller or cylinder 4 brought into contact therewith);

[0075] - then, they determine the action of memorising the “male”-type raised profile of the first roller or cylinder 4 on the “female”-type contrast profile (which thus becomes corresponding and complementary to the “male”-type profile) of the second roller or cylinder 3, by virtue of the pressure exerted by the former on the latter;

[0076] - finally, and simultaneously, they imprint the relief which is intended to be overprinted (represented by said complementary “male”- and “female”-type profiles) on the flexible support 2 as it passes and is pressed between the first roller or cylinder 4 and the second roller or cylinder 3.

[0077] According to an implementation option, the second roller or cylinder 3 is made of a material with plastic characteristics, adapted to be superficially modified, in order to “memorize” said “female”-type profile when the surface of the second roller or cylinder 3 is in contact with the surface of the first roller or cylinder 4 shaped by said “male”-type profile.

[0078] In accordance with an embodiment, the overprinting system 10 is adapted to be integrated into, and interoperate with, one or more vertical and / or horizontal packaging machines, and / or machines for making envelopes from reel at the end of the line on printing machines (excluding control means 5, 7, 9 it is possible to continuously overprint Braille characters on support 2) and / or machines with a reel unwinder.

[0079] Hereinafter, an overprinting method for producing three-dimensional reliefs on a flexible support, according to the invention, executable by means of the overprinting system 1 according to the invention, in the various previously described embodiments, is described.

[0080] In particular, an overprinting method for producing three-dimensional reliefs on a flexible support is described, comprising the following steps:

[0081] - unwinding a flexible support, wherein preset zones to be overprinted are present, through an unwinding path passing between a first rotatable roller or cylinder 4 and a second rotatable roller or cylinder 3 included in at least one printing assembly 20; the first rotatable roller or cylinder 4 operates as a plate-holder roller, and has on its surface a printing plate with a “male”-type raised profile, corresponding to the relief which is intended to be overprinted; the second rotatable roller or cylinder 3 operates as a contrast roller, and is adapted to memorize on its own surface, when placed in a condition of mutual pressure with the first roller or cylinder 4 under operating conditions of the overprinting system, a “female”-type contrast profile, corresponding and complementary to said “male”-type profile, so that the combined action of said “male”-type raised profile and “female”-type contrast profile results in the transfer of the relief which is intended to be overprinted onto the flexible support 2 to be overprinted, when the flexible support 2 passes between the first roller or cylinder 4 and the second roller or cylinder 3;

[0082] - commanding in a controllable manner, by means of actuation means 7, the rotation of the first roller or cylinder 4 and the advancement of the flexible support 2 along the unwinding path;

[0083] - controlling the actuation means 7, by means of control means 5, 9, so as to coordinate the rotation of the first roller or cylinder 4 and the advancement of the flexible support 2, to determine a correspondence of the preset zones to be overprinted of the flexible support 4 with the printing plate of the first roller or cylinder 4 and respective “male”-type raised profile, and with the complementary “female”-type contrast profile of the second roller or cylinder 3;

[0084] - imprinting the relief which is intended to be overprinted on the preset zones to be overprinted of the flexible support 2 as they pass and are pressed between the first roller or cylinder 4 and the second roller or cylinder 3.

[0085] According to an embodiment, the overprinting method comprises the following further steps:

[0086] - controlling the rotation of the first roller or cylinder 4, and also controlling the position of the first roller or cylinder 4 in a direction perpendicular to the movement direction of the flexible support 2, so that the first roller or cylinder 4 comes into contact, by applying a predefined and adjusted pressure, with the second roller or cylinder 3, at least at the moment when the flexible support 2 passes between the first roller or cylinder 4 and the second roller or cylinder 3;

[0087] - by means of the contact and pressure between the two rollers or cylinders, rotating the second roller or cylinder 3 in a coordinated manner with the first roller or cylinder 4, wherein the coordination of the rotations is obtained automatically due to the fact that the second roller or cylinder 3 rotates as a result of the rotation of the first roller or cylinder 4 when in contact therewith;

[0088] - by means of the contact and pressure between the two rollers or cylinders, causing the action of memorizing the “male”-type raised profile of the first roller or cylinder 4 on the “female”- type contrast profile, which thus becomes corresponding and complementary to the “male”-type profile, of the second roller or cylinder 3, by virtue of the pressure exerted by the former on the latter;

[0089] - by means of the contact and pressure between the two rollers or cylinders, imprinting the relief which is intended to be overprinted, represented by said complementary “male”- and “female”-type profiles, on the preset zones to be overprinted of the flexible support 2 as they pass and are pressed between the first roller or cylinder 4 and the second roller or cylinder 3.

[0090] According to other specific implementation examples of the process, the method steps are carried out by means of an overprinting system 1 according to any of the embodiments and implementation examples already previously described.

[0091] With further reference to Figure 1, a detailed description of a particular embodiment of the overprinting system is provided below, purely by way of example and without limiting purpose.

[0092] In Figure 1, the following elements are shown:

[0093] 1. reel

[0094] 2. flexible film (i.e. flexible support) being unwound

[0095] 3. contrast roller (corresponding to said “second roller”);

[0096] 4. plate-holder roller (corresponding to said “first roller”)

[0097] 5. photocell

[0098] 6. hot air generator 7. actuation with control means

[0099] 8. packages overprinted with Braille characters and / or other reliefs.

[0100] It is noted that figure 1 illustrates a situation in which the reel is unwound in a counterclockwise direction.

[0101] The plate-holder roller 4 is equipped with a motor, for example a “brushless” motor, the actuation of which includes a photocell 5 that detects the notch of the cut pitch (and is integrated with the actuation) and operates as a reference control via the command of the brushless motor; an “encoder” and a tachometric dynamo ensure reference synchronisation, that is, the coordination of the relief with the packaging (portion of the support) even in the case of “intermittent” advancement.

[0102] The plate-holder roller 4 is also provided with a transverse movement device (for example, manual) and a movement device orthogonal to the movement direction of the support (an “up and down” movement), which may be pneumatic devices.

[0103] A pressure adjustment device is also provided, comprising, for example, a pressure gauge and / or adjustable end-of-stroke screws.

[0104] The contrast roller is equipped with manual + / - adjustment means for the roller plane.

[0105] With the above-described system and method, it is possible, in addition to Braille characters, to simultaneously insert other raised graphic elements such as, for example, trademarks, logos, inscriptions, drawings, figures, and so on.

[0106] The group of elements formed by the aforementioned elements 3, 4, 5, 6, 7 is independent, and can be applied in-line, in particular on packaging machines and machines provided with a reel unwinder, such as vertical packaging machines and horizontal packaging machines, machines for making envelopes from reel at the end of the line on printing machines (excluding control means 5, 7, 9 it is possible to continuously overprint Braille characters on support 2), and so on, and is interfaced with them via the actuation device with control means.

[0107] According to an implementation option, the plates with which the plate-holder roller is equipped may also be made of brass.

[0108] According to an implementation option, the contrast roller 3 does not require a “counterplate.” In this case, the contrast roller 3 has a particular structure that allows it to memorize the “male” plate carried by the roller 4, thus becoming a “female” profile and resulting in the transfer of the relief to the flexible support 2.

[0109] According to an implementation solution (A), the plate-holder cylinder 4 is provided with an electrical resistor inside it, and acts as a “calender” capable of acting on the “inner” side of the flexible support to be relief-printed.

[0110] According to another implementation solution (B), the system comprises a hot air generator 6, for example of the “Leister” type, capable of acting instead on the “outer” side of the support, so as to facilitate the relief.

[0111] The definition of the relief result on the support, and therefore the decision whether to activate only solution (A), or only solution (B), or both (A+B), depends on the composition of the flexible support (for example, mono, duplex, triplex). The composition of the support to be overprinted is thus the variable on the basis of which one of the aforementioned implementations (A), or (B), or (A+B) is selected.

[0112] According to an implementation option, no thermal treatment is performed. This option is suitable, for example, in the case of “mono” materials, which have the characteristic of retaining the embossed relief without the need for thermal treatment (for example, aluminium).

[0113] According to an implementation option, the thermal devices (A) and (B) mentioned above are adjusted by respective thermostats, which adjust their respective temperatures based on preset temperatures.

[0114] According to an implementation option, a tachometric dynamo, via an “inverter”, controls the airflow of the hot air generator 6, in solution (B), located upstream of the contrast roller 3, based on the advancing speed of tape 2.

[0115] According to various application examples, the overprinting system is capable of producing, starting from a reel 1 printed with a smooth surface, three-dimensionally embossed bags / pouches 8, or a reel printed with three-dimensional embossing 8, or, starting from a neutral reel 1 with a smooth surface, a neutral reel 8 or neutral bags / pouches 8, with three- dimensional embossing.

[0116] As can be seen, the object of the present invention is achieved by the above-described system and method.

[0117] Indeed, based on the above, it is evident that the system according to the invention is capable, by virtue of its characteristics, of enabling improved, effective and precise overprinting in relief on a flexible support.

[0118] In particular, thanks to the above-described system and method, it is possible to meet the need to overprint Braille characters with good quality, suitable for the particularly stringent requirements of such application, on already previously printed supports.

[0119] In this way, the above-described system and method are also capable of providing the advantages of overprinting (for example, effective reuse of already used supports) and of three- dimensional printing.

[0120] To the embodiments of the system and method of overprinting according to the invention described above, the person skilled in the art, to meet contingent needs, may make modifications, adaptations, and replacements of elements with others functionally equivalent, even in combination with the known art, also creating hybrid implementations, without departing from the scope of the following claims. Each of the features described as belonging to a possible embodiment may be implemented independently of the other described embodiments.

[0121] It should also be noted that the term “comprising” does not exclude other elements or steps, the term “a” or “an” does not exclude a plurality. Moreover, the figures are not necessarily to scale; rather, importance is generally given to illustrating the principles of the present invention.

Claims

CLAIMS1. An overprinting system (10) for producing three-dimensional reliefs on a flexible support, comprising:- a flexible support (2) wherein preset zones to be overprinted are present;- at least one printing assembly (20), in turn comprising:- a first rotatable roller or cylinder (4), operating as a plate-holder roller, having a printing plate on the surface with a raised profile of the “male” type, corresponding to the relief which is intended to be overprinted;- a second rotatable roller or cylinder (3), operating as a contrast roller, adapted to memorize on its own surface, when placed in a condition of mutual pressure with the first roller or cylinder (4) under operating conditions of the overprinting system, a contrast profile of the “female” type, corresponding and complementary to said “male”-type profile, so that the combined action of said “male”-type raised profile and “female”-type contrast profile results in the transfer of the relief which is intended to be overprinted to the flexible support (2) to be overprinted, when the flexible support (2) passes between the first roller or cylinder (4) and the second roller or cylinder (3);- actuation means (7) configured to command, in a controllable manner, the rotation of the first roller or cylinder (4) and the advancement of the flexible support (2) along an unwinding path, upstream of the printing assembly (20) in the unwinding direction and passing through said printing assembly (20);- control means (5, 9) configured to control the actuation means (7), so as to coordinate the rotation of the first roller or cylinder (4) and the advancement of the flexible support (2), to determine a correspondence of the preset zones to be overprinted of the flexible support (4) with said printing plate of the first roller or cylinder (4) and respective “male”-type raised profile, and with the complementary “female”-type contrast profile of the second roller or cylinder (3), so as to imprint the relief which is intended to be overprinted on the preset zones to be overprinted of the flexible support (2) as it passes and is pressed between the first roller or cylinder (4) and the second roller or cylinder (3).

2. An overprinting system (10) according to claim 1 , further comprising heat treatment means configured to heat, in a controllable manner, one or the other or both sides of the flexible support (2) and / or of the related zones to be overprinted, to facilitate the overprinting of the relief on the zones to be overprinted of the flexible support.

3. An overprinting system (10) according to claim 2, wherein said heat treatment means comprise:- an electrical resistor arranged in the first roller or cylinder (4), adapted to operate as a calender and heat, in a controlled manner, the side of the flexible support referred to as the inner side, facing the first roller or cylinder (4), while it transits in contact with the first roller or cylinder (4);- a hot air generator (6) configured to heat, in a controllable manner, the other side of the flexible support referred to as the outer side, facing the second roller or cylinder (3), while it transits close to, upstream, and / or in contact with the second roller or cylinder (3).

4. An overprinting system (10) according to claim 3, wherein the control means are configured to perform, as a function of the type of flexible support to be overprinted, any of the following actions, upon the passage of the flexible support (2) between the first roller or cylinder (4) and the second roller or cylinder (3), and thus upon the overprinting action:- actuating only said electrical resistor, or- actuating only said hot air generator, or- actuating both said electrical resistor and said hot air generator, or- not actuating either said electrical resistor or said hot air generator.

5. An overprinting system (10) according to any one of claims 1-4, wherein said three- dimensional reliefs correspond to Braille alphabet writings.

6. An overprinting system (10) according to any one of claims 1-4, wherein said three- dimensional reliefs correspond to one or more relief marks and / or logos and / or inscriptions and / or drawings and / or figures.

7. An overprinting system (10) according to any one of the preceding claims, wherein the actuation means (7) of the printing assembly comprise a “brushless motor”-type actuator8. An overprinting system (10) according to any one of the preceding claims, wherein said flexible support comprises a reel (1) and wherein the actuation means (7) are configured to command the advancement of the flexible support (2) in a controllable manner by controlling the unwinding rotation of said reel (1), said advancement of the flexible support (2) being continuous or intermittent, wherein said reel (1) sequentially comprises a flexible ribbon-like strip and / or a pluralityof envelopes or bags, and / or wherein said reel (1) is pre-printed with a smooth surface or is neutral.

9. An overprinting system (10) according to claim 8, configured to provide, as a result of overprinting:- a plurality of relief-printed packages and / or bags and / or envelopes, resulting from said flexible support, and / or a reel of relief-overprinted flexible support, and comprising a second rewinding reel of said flexible support (2), once it has been relief printed, and / or wherein the overprinting system (10) further comprises a plurality of return rollers configured to arrange an unwinding path for the flexible support (2), the unwinding path being enclosed between said first reel and said second reel.

10. An overprinting system (10) according to any one of the preceding claims, wherein the control means (5, 9) comprise:- a detection device (5) configured to detect the advancement of the flexible support and / or an offset between preset zones to be overprinted of the flexible support (2) and respective printing zones of the first roller or cylinder (4);- a processing unit (9), operatively connected to said detection device (5) to receive signals indicative of the advancement of the flexible support and / or said offset, and configured to produce control signals for the actuation means (7), based on said received signals; and wherein the actuation means (7) are operatively connected to said processing unit (9) to receive said control signals.

11. A system (1) according to claim 10, wherein the flexible support (2) comprises recognition markings, or notches, adapted to signal a cut pitch and / or preset zones to be overprinted, and wherein said detection device (5) comprises:- a reading head (5) or photocell (5) arranged along said unwinding path, configured to read said recognition markings or notches.

12. An overprinting system (10) according to any one of the preceding claims, further comprising means for shifting and / or controlling the position of the first roller or cylinder (4), in a transverse direction and / or in a perpendicular direction with respect to the movement direction of the flexible support (2) upon the passage between the first and second rollers or cylinders.

13. An overprinting system (10) according to claim 12, wherein said position shift and / or control means comprise a device configured to control the position of the first roller or cylinder (4) in a direction perpendicular to the movement direction of the flexible support (2).

14. An overprinting system (10) according to claim 13, wherein said device is controlled by the control means (9) to control the position of the first roller or cylinder (4) in an automatic and coordinated manner in a direction perpendicular to the movement direction of the flexible support (2) and / or configured to adjust the mutual position between the first roller or cylinder (4) and the second roller or cylinder (3), during the relief overprinting action.

15. An overprinting system (10) according to any one of the preceding claims, wherein said second roller or cylinder (3) is configured to be freely rotatable, and wherein the rotation of the second roller or cylinder (3) is commanded, under operating conditions, by the controlled rotation of the first roller or cylinder (4), by contact and / or friction, under operating conditions in which the first roller or cylinder (4) is brought into contact with the second roller or cylinder (3), applying a controlled pressure thereto.

16. An overprinting system (10) according to any one of the preceding claims, adapted to be integrated into, and interoperate with, one or more vertical and / or horizontal packaging machines and / or machines for making envelopes from a reel at the end of the line on printing machines and / or machines with a reel unwinder.

17. An overprinting method for producing three-dimensional reliefs on a flexible support, comprising:- unwinding a flexible support, in which preset zones to be overprinted are present, through an unwinding path passing through at least one printing assembly (20), between a first rotatable roller or cylinder (4) and a second rotatable roller or cylinder (3) included in the at least one printing assembly (20), wherein the first rotatable roller or cylinder (4) acts as a plate-holder roller, having a printing plate on the surface with a “male”-type raised profile, corresponding to the relief which is intended to be overprinted, and the second rotatable roller or cylinder (3) acts as a contrast roller, adapted to memorize on its own surface, when placed under mutual pressure with the first roller or cylinder (4) under operating conditions of the overprinting system, a “female”-type contrast profile, corresponding and complementary to said “male”-type profile, so that the combined action of said “male”-type raised profile and “female”-type contrast profile results in the transfer of the relief which is intended to be overprinted on the flexible support (2)to be overprinted, when the flexible support (2) passes between the first roller or cylinder (4) and the second roller or cylinder (3);- commanding in a controllable manner, by means of actuation means (7), the rotation of the first roller or cylinder (4) and the advancement of the flexible support (2) along said unwinding path;- controlling the actuation means (7), by control means (5, 9), so as to coordinate the rotation of the first roller or cylinder (4) and the advancement of the flexible support (2), to determine a correspondence of the preset zones to be overprinted of the flexible support (4) with said printing plate of the first roller or cylinder (4) and respective “male”-type raised profile, and with the complementary “female” -type contrast profile of the second roller or cylinder (3);- imprinting the relief which is intended to be overprinted on the preset zones to be overprinted of the flexible support (2) as they pass and are pressed between the first roller or cylinder (4) and the second roller or cylinder (3).

18. An overprinting method according to claim 17, comprising the further steps of:- controlling the rotation of the first roller or cylinder (4), and further controlling the position of the first roller or cylinder (4) in a direction perpendicular to the movement direction of the flexible support (2), so that the first roller or cylinder (4) comes into contact, by applying a predefined and adjusted pressure, with the second roller or cylinder (3), at least when the flexible support (2) passes between the first roller or cylinder (4) and the second roller or cylinder (3);- by means of the contact and pressure between the two rollers or cylinders, rotating the second roller or cylinder (3) in a coordinated manner with the first roller or cylinder (4), wherein the coordination of the rotations is obtained automatically since the second roller or cylinder (3) rotates as a result of the rotation of the first roller or cylinder (4) when in contact therewith;- by means of the contact and pressure between the two rollers or cylinders, causing the action of memorizing the “male”-type raised profile of the first roller or cylinder (4) on the “female”-type contrast profile, which thus corresponds and is complementary to the “male”-type profile, of the second roller or cylinder (3), by virtue of the pressure applied by the former to the latter;- by means of the contact and pressure between the two rollers or cylinders, imprinting the relief which is intended to be overprinted, represented by said complementary “male”- and “female”-type profiles, on the preset zones to be overprinted of the flexible support (2) as they pass and are pressed between the first roller or cylinder (4) and the second roller or cylinder (3).

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