IT202100009581A1 - EQUIPMENT FOR DIGITAL PRINTING ON A CONTINUOUS TAPE - Google Patents

Description

Description

of industrial invention entitled:

EQUIPMENT FOR DIGITAL PRINTING ON A CONTINUOUS TAPE

[001] The present invention refers to the technical field of machines for printing on supports of various kinds, such as paper, cardboard, textile materials, metal materials, wood materials, plastic materials, minerals or the like. In particular, the present invention relates to a system for feeding a continuous ribbon (reel of ribbon material) to an inkjet printer used for printing said ribbon.

[002] In a preferred embodiment, the printed tape is a metal tape, for example steel or aluminum for printing. In an alternative form, said tape ? in plastic or paper material. In a further embodiment, this tape is a coupled formed by two or more? of these materials.

[003] Said continuous strip has any length, a width that can ranging from 200 mm to 6000 mm, and a variable thickness between 0.006 mm and 5 mm.

[004] Said continuous tape is printed on only one surface, the upper surface (printing surface). The opposite, lower surface is not printed and must be kept clean to avoid soiling the printed surface.

[005] Said ribbon is cut after printing to obtain sheets or ribbons (that is, ribbons of any length but smaller in width than the original) of the desired dimensions.

[006] In the case of metal tape, such sheets or strips are used, for example, in urban furniture, in the production of sandwich panel products for making walls or insulation for walls, for making shaped profiles, for making metal surfaces decorated for internal or external use, for the creation of both flexible and rigid metal packaging.

[007] Printing apparatuses are known, for example of the inkjet type, for printing on substrates such as paper, cardboard, polymer sheets or panels, tiles, billboards or the like, substrates used in various sectors, and on different types of substrate materials, generally comprising one or more unit? of printing installed above a carriage and a support surface, for example a belt, a surface or a carpet, in which an article to be printed is positioned and possibly advanced in cooperation with the printing group.

[008] Single-pass printers and multi-pass printers are known in the art. Single-pass machines are machines in which the print heads are mounted on a fixed support, while the support to be printed is advanced under the print heads themselves. By multi-pass machines, on the other hand, we mean machines in which the print heads are mounted on a mobile support (carriage) which moves perpendicularly to the direction of advancement of the substrate to be printed.

[009] On each unit? of printing ? installed a plurality? of print heads, each of which ? equipped with dispensing nozzles mutually arranged in a coordinated way, in order to carry out the correct printing sequence with the pre-set materials and colours.

[0010] The unit? print can? also be provided with, or cooperate with, a drying device, normally a UV (Ultra Violet) or IR (Infra Red) or EB (Electron Beam) lamp or other similar or similar device for drying or irradiation, for substantially drying Snapshot of the print material at the end of its cycle.

[0011] Each of the units? of printing allows the supply of at least one color, for example primary colors (cyan, magenta and yellow), neutral colors (black and white), as well as? any additional colors (spots) both for increasing the range of colors (gamut) and for special flat colors. Each unit? print includes up to two print bars; a print bar includes a plurality? of commercial printheads lined up; each print bar delivers a single color.

[0012] ? It is known that in single-pass machines the print bars are generally supported by a support plate on which they are fixed in a precise position to perform the print correctly.

[0013] One of the problems of tape printing, and in particular of printing using ink jet printers, is to obtain a precise and repeatable positioning of the tape with respect to said units? of printing. In fact, the properties The mechanics of metal or plastic tape are somewhat different from those of paper in reels which is normally used as a printing support. This does s? that paper roll conveyance methods are being applied to continuous metal or plastic web with questionable results.

[0014] For example, EP3599098A1 proposes to use continuous metal ribbon in reels placed upstream and downstream of the printing apparatus. These reels are respectively unwound and rewound as printing progresses. This printing apparatus includes a unit? driving input and a unit? for guiding said continuous metal strip out, and a conveyor belt arranged to advance said continuous metal strip through the printing zone.

[0015] In a preferred embodiment, this conveyor belt can be equipped with an upper horizontal branch connected to a suction source, to hold the continuous metal strip by means of suction during its passage through the unit? of digital printing.

[0016] This conveying system has the disadvantage that during printing the metal strip can move laterally, which leads to the fact that sometimes the ink can? end up on the conveyor belt instead? on the metal tape. Once the conveyor belt is ? dirty, a thickness of cross-linked ink is formed which jeopardizes the adherence of the metal band to the conveyor belt. For this reason, printing with an inkjet printer according to EP3599098A1 can take place only up to a few millimeters from the edge, in order to ensure that the conveyor belt always remains clean. Furthermore, if the conveyor belt is reached by the thrown ink, it can soil the underside of the metal tape opposite the print side. Finally, since the conveyor belt is less rigid than the metal belt, the lateral guide function of the conveyor belt is? ineffective.

[0017] The purpose of the present invention? the creation of an inkjet printing apparatus capable of printing on continuous tape, guaranteeing good quality? print up to the side margins of the ribbon.

[0018] This purpose? obtained with an apparatus having the characteristics of the independent claims. Advantageous embodiments and refinements are specified in the dependent claims.

[0019] This apparatus? consists of an inkjet printer that has below the unit? printing a desired number of rollers which allow the advancement of said ribbon to be printed; these rollers are placed between the units? of printing. In other words, printing takes place in points of the web below which said rollers are not located. Said rollers can be idle rollers or alternatively said rollers can be motorized.

[0020] In a preferred embodiment, the continuous tape is a metal ribbon.

[0021] The ribbon to be printed has dimensions that vary from a maximum to a minimum width, but the center line of said ribbon is always in the same position with respect to the units? of printing; varies instead the position of the side edges of the tape to be printed with respect to the unit? of printing.

[0022] The said rollers which support the tape below the units? print are longer than the width of the tape to be printed.

[0023] Laterally there are devices for collecting the ink which does not end up on said ribbon to be printed; preferably said collection devices are in turn equipped with devices for removing any ink which accidentally ends up on the surface opposite the printing surface.

[0024] Substantially, the improvements made by the present invention with respect to the prior art include:

to. an ink collection system thrown over the edge of the web to be printed;

b. an optional ink removal system unfortunately ended up on the lower surface of the ribbon to be printed;

c. an optional belt stabilization and vibration damping device.

[0025] A first advantage of the present invention? the possibility? to get a better quality? continuous ribbon printing.

[0026] A second advantage of the present invention? the possibility? to print up to the side margins of the tape.

[0027] A third advantage of the present invention? use a conveyor belt system more continuous? simple and cheap compared to the prior art.

[0028] Further advantages and features of the present invention are described in the following description, wherein exemplary embodiments are explained in detail based on the drawing:

Figure 1 Side view of a production line, with an inkjet printer in a first embodiment;

Figure 2 Top view of the same production line, with inkjet printer in the first embodiment;

Figure 3 Side view of the detail of the inkjet printer, second embodiment;

Figure 4 Side view of the detail of the inkjet printer, third embodiment.

[0029] The figures mentioned above show a plant for printing metal strips with inks, without thereby losing generality. The printer ? preferably a single-pass printer.

[0030] Figure 1 shows a side view of a production line 100 comprising an inkjet printer 101 according to the first embodiment of the present invention. The bold arrow shows the direction of tape advance.

[0031] The ribbon to be printed can have different widths, between a minimum and a maximum design width, for example from 200 mm to 1500 mm.

[0032] Said production line 100 comprises an unwinder 1 of a reel 2 of tape. The unwound tape? indicated by 3. As the reel is unwound and its diameter decreases, an arm 4 is moved to move to a suitable position for sliding of the ribbon.

[0033] The unwound tape 3 is made to pass through a known rectifier 5 which comprises several rollers.

[0034] Subsequently, the unwound ribbon is made to pass through a bridle made up of two rollers 6 and 7. In particular, the ribbon first passes on roller 7 and then goes back on roller 6 to then pass under a subsequent roller 8 Once you leave reel 8, the tape path becomes vertical (labeled 9).

[0035] The tape then passes horizontally over a tape guide made up of two rollers 10. The purpose of the tape guide is to hold the tape in its correct position, to do what? so that the tape does not drift to the right or left of its midline.

[0036] Downstream of the tape guide, the path of the tape becomes vertical again (indicated by 11).

[0037] Optionally, on the vertical section 11 of the unwound tape it can be placed a heater 12 which has the purpose of heating the tape, so as to make s? that the ribbon has a temperature compatible with that which makes the ribbon printable. Indicatively, the optimal printing temperature? 20?C; the humidity plays an important role.

[0038] The possibly preheated ribbon passes under two rollers 13 and 14, and above a roller 15 to then enter (indicated by the number 16) inside the inkjet printer 101.

[0039] In the position 16 of the ribbon, after the bridle constituted by the rollers 14 and 15, but before the printer 101, a suitable system 36 for pre-treatment of the ribbon is optionally mounted, for example a corona treatment, or a flame treatment, or a plasma treatment, in order to maintain the surface tension of the ribbon within the range foreseen for printing.

[0040] The unwound tape 16 passes over any number of rolls 17, in this case seven rolls 17, to be printed.

[0041] The first embodiment shown here of the inkjet printer 101 is equipped with two units? of printing 19, for example the first for printing cyan (C) and magenta (M), and the second for printing yellow (Y) and black (K).

[0042] Preferably, downstream of said units? of print 19, ? place a device at 20 for the gelling of the inks, for example a UV LED device. This ink gelling device can be placed downstream of all the units? of print 19, as shown in the Figure, or be placed between one print head and another, depending on the effective length of the printer 101 and on the number of colors that are printed.

[0043] Downstream of the inkjet printer 101, the printed ribbon, indicated by 21, enters a unit? 22 of drying/crosslinking of inks and varnishes which has the purpose of definitively fixing there? That ? been thrown onto the ribbon by the 101 inkjet printer.

[0044] Subsequently, the printed and dried ribbon passes through a bridle consisting of two rollers 23 and 24; in particular, the tape passes above the roller 23 and below the roller 24, to then take a vertical course (indicated with 25) and pass over a roller 26.

[0045] Downstream of the roller 26, the ribbon resumes a horizontal course indicated by 27, to then form a loop passing in a bridle made up of two rollers 28 and 29; in particular, the tape wraps the roller 29 and then the roller 28 for three quarters of the useful circumference.

[0046] Downstream of the roller 28, the printed and dried web again takes on a horizontal course (indicated with 30).

[0047] Continuing along the line there is a quality control station 31, which can be performed by a human operator and/or by an automatic vision system.

[0048] Downstream of the quality control station 31? the printed and dried tape continues on its horizontal path (indicated with 32), resting on an arm 33 which has the purpose of accompanying the tape 32 in its rewinding in a reel 34 placed inside a winder 35.

[0049] Figure 2 shows a top view of the same production line 100. The bold arrow shows the direction of advancement of the tape.

[0050] Figure 2 allows to observe the position of the tape, of which the left 41 and right 42 edges are shown respectively, while the central line 40 indicates the center line of the tape.

[0051] The technical solution provides that the center line 40 always maintains the same position with respect to the inkjet printer, regardless of the width of the web.

[0052] The ribbon is tensioned and set in motion above the rollers 17, which have the purpose of stabilizing its movement, minimizing vertical vibration and precisely maintaining the distance of the ribbon from the print heads of the inkjet printer 101.

[0053] ? good to specify that each of the units? of print 19 ? placed between one roll 17 and another, while the ribbon is printed when it is not on a roll 17 (better seen in Figures 3 and 4).

[0054] Said rollers 17 are more? lengths of the maximum width of the tape: for example, if the tape has a maximum width of 1500 mm, roll 17 will have? indicatively a width of 1800 mm.

[0055] Between one roll 17 and the other, below the units? of printing 19, suitable devices 37 are positioned (better visible in Figures 3 and 4) for collecting the ink which is thrown beyond the effective width of the web.

[0056] For example, if the ribbon to be printed has a width of 1200 mm, will the printer print? a slightly exceeding width, for example 1220 mm (10 mm to the right and 10 mm to the left beyond the side margins 41 and 42) thus guaranteeing a quality? of perfect printing up to the lateral margins 41 and 42, even in the case of a lateral deflection of the web.

[0057] The ink collection devices 37, for example in the form of trays, are optionally equipped with devices for removing any ink which unfortunately should end up on the lower face (opposite to the printing face) of the ribbon, for example in the form of scrapers (not shown).

[0058] The tape 16 must be below the units? of printing 19, at a vertical distance of 1-2 mm, maximum 5 mm, from said units? of print 19.

[0059] The rollers 17 preferably do not lie on the same plane, but are placed staggered in height, so that the central roller is more? top of the two adjacent rolls, to form a curved profile and ensure minimum wrap of the tape 16 on the rolls 17. In other words, the rolls 17 are positioned so that each roll has a guaranteed minimum wrap of the tape.

[0060] If the ribbon to be printed is metallic, said rollers 17 are preferably idle rollers, i.e. they are dragged along by the movement of the metal strip.

[0061] In the event that the tape is not of metallic material, but is made of flexible or in any case non-rigid materials (for example plastic materials), the rollers 17 can instead be motorised, since the properties? mechanical characteristics of the material may not be such as to allow the dragging of the rollers 17.

[0062] ? Is it possible that the tape 16 starts to vibrate, for example, in the changes of speed? of advancement of the tape, or to the passage of the splice between two successive reels. To avoid altering the distance between the tape and the drives? which would lead to a printing defect or even damage to the printer, known vibration damping devices are provided between one roller 17 and the other, which can be mechanical or electromagnetic or pneumatic or a combination thereof.

[0063] These systems for stabilizing the web and damping the vibrations under the print heads can be of the mechanical type, such as for example precision planes positioned near the print heads. of the lower surface of the tape itself, and suitably equipped with a vacuum system (also called vacuum) which guarantees the adhesion of the tape with said surface, on which the tape slides.

[0064] Alternatively, they can be made with a series of motorized or towed stabilizing belts which, by means of a vacuum system and/or an electromagnetic system, adhere to the lower surface of the belt to be printed, and being mechanically guided and rigid, transport it into the correct direction by limiting any lateral and vertical movements.

[0065] These stabilizing devices can be positioned between one roller 17 and the next or they can be extended to cover the entire path affected by the printing and incorporate the rollers 17 themselves.

[0066] These stabilizing and guiding devices can translate transversely to the movement of the web to adapt to the different widths of the web to be printed.

[0067] Figures 3 and 4 show two embodiments of the inkjet printer. In particular, the variation ? linked to the number of units? of printing elements 19 which are provided in the printers 102 and 103, although the same constructive principles are applied also in these embodiments. ? it is obvious that these inkjet printers 102 and 103 can replace the inkjet printer 101 within the production line 100.

[0068] Figure 3 shows the second embodiment 102 of the inkjet printer according to the present invention, built according to the same principles explained above.

[0069] This second embodiment of the inkjet printer 102 provides for the use of four units? of print 19, for example the first of which prints black (K) and cyan (C), the second of which prints yellow (Y) and magenta (M), the third of which prints magenta (M) and yellow (Y), and the fourth of which prints cyan (C) and black (K). The redundancy of the units? print allows you to ensure a better quality? of the printed product. As explained above, each unit? of print 19 ? positioned above a stretch of unwound tape 16 which does not rest on a roller 17. At each unit? of print 19 ? placed a device 37 for collecting the thrown ink which is not? finished on the tape, and optionally a tape stabilization and vibration damping device.

[0070] How already? explained, an ink gelling device 20 can be placed downstream of all the units? print 19 as shown in the Figure, or pu? be used a plurality? of gelling devices 20, which are placed between a unit? of print 19 and the other.

[0071] Figure 4 shows a third embodiment 103 of the inkjet printer according to the present invention, built according to the same principles explained above.

[0072] This second embodiment of the inkjet printer 103 provides for the use of six units? of print 19, for example the first and second of which print a spot color (F), the third of which prints cyan (C), the fourth of which prints magenta (M), the fifth of which prints yellow (Y), and the sixth of which prints black (K). As explained above, each unit? of printing ? positioned in an unwound section of tape 16 which does not rest on a roller 17. At each unit? of print 19 ? placed a device 37 for collecting the thrown ink which is not? finished on the tape and optionally a tape stabilization and vibration damping device.

[0073] How already? explained, an ink gelling device 20 can be placed downstream of all the units? print 19 as shown in the Figure, or pu? be used a plurality? of gelling devices 20, which are placed between a unit? of print 19 and the other.

unwinder

coil

unwound tape

arm

rectifier

roller

roller

roller

vertical portion of ribbon unwound bridle

vertical portion of tape unwound heater

roller

roller

roller

unwound tape

roller

stretch of tape between units? of print unit? of printing

unit? of gelation

unwound tape

unit? of curing/roller drying

roller

vertical section of tape unwound on a roll

horizontal stretch of tape unwound on a roll

roller

unwound tape

quality control station horizontal stretch of tape unwound arm

coil

winder

web pretreatment system central line ink recovery device

left margin

right margin

productive line

inkjet printer

inkjet printer

inkjet printer

Claims (10)

Claims 1. Inkjet printing apparatus (101, 102, 103) for printing continuous web on one of the two surfaces, called the printing surface, comprising: ? at least one unit? print bar (19) for printing at least one colour, each provided with at least one print bar; ? a support structure provided for supporting said continuous strip below said units? of print (19); characterized in that ? said support structure of said continuous ribbon to be printed comprises at least two rollers (17) having a length greater than the width of the ribbon to be printed; ? the said units? printing presses (19) print said continuous ribbon at points located between two adjacent rollers (17). 2. Inkjet printing apparatus (101, 102, 103) for printing continuous web according to claim 1, wherein devices (37) are provided at the printing positions of the printing bars (19) for collection of the ink thrown beyond the side edges (41, 42) of the ribbon to be printed. 3. Inkjet printing apparatus (101, 102, 103) for printing continuous web according to claim 2, wherein said collection devices (37) are further provided with devices for removing the ink accidentally finished on the opposite surface to the print surface of the ribbon. 4. Ink jet printing apparatus (101, 102, 103) for printing continuous ribbon according to one or more of the previous claims, in which between a unit? press (19) and the other, and/or downstream of all the units? of print (19) ? at least one device (20) for gelling the inks is arranged. 5. Ink jet printing apparatus (101, 102, 103) for printing continuous ribbon according to one or more of the previous claims, in which downstream of the unit? of printing (19) and of the at least one optional device (20) for gelling the inks ? expected a unit? (22) crosslinking/drying the inks printed by the printer (101, 102, 103). 6. Ink jet printing apparatus (101, 102, 103) for printing continuous ribbon according to one or more of the preceding claims, wherein upstream of the apparatus (101, 102, 103) ? provided a heater device (12) to bring said ribbon to a suitable temperature for printing, while upstream of the apparatus (101, 102, 103), but downstream of said optional heater device (12) ? a pre-treatment system (36) is provided for the strip selected from the group consisting of: corona treatment, or flame treatment, or plasma treatment. 7. Ink jet printing apparatus (101, 102, 103) for printing continuous ribbon according to one or more of the preceding claims, wherein the ribbon to be printed is in metallic material or in plastic or paper material or derivative due to the coupling of two or more? of these materials. 8. Inkjet printing apparatus (101, 102, 103) for printing continuous web according to claim 8, wherein said rollers (17) are idle rollers, or alternatively they are motorised. 9. Ink jet printing apparatus (101, 102, 103) for printing continuous ribbon according to one or more of the preceding claims, equipped with at least one device for stabilizing the tape and damping the vibrations of the mechanical, pneumatic or electromagnetic type or a combination of these, which can be positioned transversally with respect to the direction of advancement of the tape. 10. Ink jet printing apparatus (101, 102, 103) for printing continuous tape according to one or more of the preceding claims, wherein the ribbon to be printed has any length, a width from 200 mm to 6000 mm, and a thickness ranging from 0.006 mm to 5 mm.