RU2490137C2 - System of ink application for gravure printing machine - Google Patents

Abstract

FIELD: printing industry.

SUBSTANCE: system for a gravure printing machine comprises at least a reservoir for ink application onto the surface of the engraved optional rolling cylinder (35), which in its turn applies ink onto the surface of the gravure cylinder (39) of the gravure printing machine with a stencilled shaft (40), having relief ledges corresponding to engravings (38), which are filled with ink on the specified gravure cylinder. The specified system of ink application additionally comprises a wiping system (8, 9) designed to wipe the surface of the specified optional rolling cylinder and to regenerate the wiped ink in the reservoir.

EFFECT: improved printing quality and reduced ink consumption.

24 cl, 6 dwg

Description

The present invention relates to a paint application system for an intaglio printing press printing securities such as banknotes, as well as checks, passports, identity cards and other similar objects.

In the field of multicolor intaglio printing, it is known that it is necessary to fill both small and deep engraved lines of the intaglio form with the exact amount of ink in order to obtain good print quality while minimizing the excess ink needed to fill small engravings, as well as the amount of ink transferred to non-engraved gravure printing shape, thereby increasing machine productivity and reducing ink consumption.

Examples of known printing machines are shown in US patent No. 4516496, 5062359 and 5899145, the contents of which are incorporated into this application by reference.

The state of the art in the field of printing machines and intaglio printing methods provides for a paint application system with coarse regulation of the amount of ink along the axis of the printing cylinder, although it does not provide control means along the peripheral surface of this cylinder.

For example, finer adjustments are known from US Pat. No. 4,604,951, which describes an intaglio printing machine having a conventional configuration, characterized by a duct shaft with recesses holding the ink and having different depths corresponding to the depths of the form. This machine has never been implemented in industrial production, as it has the following disadvantages:

the configuration of the machine provides only a direct method of applying paint;

it is impossible to precisely match the described recesses holding the paint and made on the cylinder of the duct shaft with engraved drawings in the form of intaglio printing;

the arrangement of the ductile shaft and knife described in the aforementioned patent requires a continuous cylindrical surface incompatible with the presence of form clamping devices; engraved forms are much easier to manufacture, install and maintain than cylinders fitted with dekel;

it is impossible to precisely control the high stiffness of the colorful knife with the help of adjusting screws;

the presence of a gap between the colorful knife and the duct shaft causes the appearance of a large amount of paint on the un engraved surface of the duct shaft, and then on the non-engraved intaglio printing surface, which does not allow for economical use of ink;

an additional reduction in the gap between the colorful knife and the duct shaft inevitably leads to the knife coming into contact with the duct shaft and damage to both the knife and the cylindrical surface.

In accordance with the prior art, other systems have been developed to improve the accuracy of ink deposition and to reduce ink consumption, see, for example, European patent application published under number 1442878, the contents of which are incorporated into this application by reference. The aforementioned patent application relates to an intaglio printing machine in which selective cylinders used for applying paint to a pick-up cylinder are driven independently by rotation of the drives, providing a change in the length of the painted print on the rubber sheet of the pick-up cylinder.

Another example is described in the application for a European patent published under the number 1445098, the contents of which are incorporated into this application by reference. In the aforementioned patent application, the offset cylinder for the intaglio printing machine is made with different layers, each of which has different properties. The said layers are engraved and can be lipophilic and / or lipophobic, which makes it possible to achieve very accurate application of paint to the plate cylinder.

Therefore, the aim of the present invention is the improvement of known machines and methods.

An additional objective of the present invention is to provide a printing machine and printing method that does not have the disadvantages of the prior art.

Another objective of the present invention is to provide a printing machine and intaglio printing method, which are easier to implement and provide excellent performance in relation to print quality and ink consumption.

The achievement of these goals is ensured by the fact that the invention meets the wording of the claims.

The present invention will be best understood after reading the description of several options for its implementation with reference to the accompanying drawings, in which:

FIG. 1 is a first embodiment of a paint application system in accordance with the present invention;

FIG. 2 is a second embodiment of an ink coating system in accordance with the present invention, illustrating a first configuration of a printing press;

FIG. 2b is the configuration option of FIG. 2;

FIG. 3 is yet another configuration of a printing press with an ink coating system in accordance with the invention;

FIG. 4 is an additional configuration of a printing press with an ink coating system in accordance with the invention;

FIG. 5 is a “multi-color” configuration of a printing press with an ink coating system in accordance with the invention.

In FIG. 1 shows a first embodiment of a paint application system in accordance with the invention. In this embodiment, there is a reservoir, designated as a whole by reference numeral 1, wherein said reservoir comprises a duct shaft 2, a paint adjustment knife 3 for the duct shaft 2 and a paint source 4. The duct shaft applies paint to a selective rolling cylinder 5, which has an engraved surface. The surface of the sample rolling cylinder 5 can be engraved directly, or, in a preferred embodiment, the cylinder can bear an engraved shape with engravings corresponding to the pattern, which should be painted in a given color. As is known in the art, the rolling cylinder comprises a cavity 7 in which there are clamping means (not shown) for holding the mold 6 in a predetermined position.

The paint application system further comprises a wiping roller 8, preferably a dry wiping roller, which is used to wipe the surface of the rolling cylinder 5, so that only the paint present in the engravings of the rolling cylinder 5 remains, and the paint present on the non-engraved surface of the cylinder 5, completely removed.

The wiping system further comprises a doctor blade 9 for scraping the surface of the wiping roller in order to remove ink from non-engraved gravure printing elements, and the ink scraped in this way is regenerated in the ink source 4, as shown in FIG. one.

Accordingly, the function of supplying ink from the reservoir is separated from the function of adjusting the thickness of the ink. The duct shaft 2 supplies excess paint to a selective rolling cylinder 5 through a duct shaft knife 3. You can not equip this knife with adjusting screws, because there is no need for axial adjustment of the amount of paint. It is not necessary and precisely to adjust the gap between the knife 3 for the duct shaft and the duct shaft 2. As an example, it should be noted that if a gap of, for example, 80 μm is required for the maximum amount of paint required, this gap can be adjusted with a wide excess tolerance, for example, 100-300 microns. The reason is that the duct shaft 2 does not perform the function of regulating the paint. The duct shaft 2 is preferably coated with hard rubber or plastic (for example, polyvinyl chloride (PVC) with an appropriate hardness in units of Shore scale D at 50 °). This shaft is removed from the press for maintenance or replacement and is equipped in accordance with the state of the art of the state of the art to provide regulation of contact with the circulating fluid for thermoregulation. In addition, this shaft is preferably configured to quickly automatically turn on / off movement at each revolution in order to avoid transferring paint to the mold near the bend position.

A selective rolling cylinder 5 has the function of regulating the paint and is equipped, as mentioned above, with a mold clamping device for engraved mold 6, usually a nickel-chromium mold. The engraved form 6 is in contact with the roller shaft 2 and receives excess paint from it, and the transfer of paint occurs both in the engraved recesses of form 6, and on the surface of the form. After exposure to the dry wiping roller 8, each point of the engraved shape carries the exact (or slightly excess) amount of ink needed for the intaglio printing method.

The dry wiping roller 8 is located above the duct shaft 2, is in contact with a selective rolling cylinder 5 and rotates in the same direction, so that the two surfaces in contact move in different directions. Similar to a conventional wiping unit wiping the intaglio printing form, the dry wiping roller 8 removes excess paint from the surface of the mold 6, leaving the ink engraved. Excess paint is transferred to the surface of the roller 8 for dry wiping, and the doctor blade 9 removes most of the paint from the surface of the roller 8 for wiping. The removed paint falls by gravity into the tank 1, and therefore it can be reused.

As the roller 8 for dry wiping, and the doctor blade 9 is made with the possibility of unsynchronized axial movement to even out wear on the surface of the roller. This roller is preferably coated with hard rubber or plastic (for example, PVC with an appropriate hardness in units of Shore D scale at 50 °). The dry wiping roller 8 is preferably driven by an independent electric motor in order to optimize rotation speed to minimize the amount of paint in the non-engraved area of form 6 selectively coated with paint. Its thickness is in the range of up to several microns. The doctor blade 9 is preferably steel having a ceramic coating. Alternatively, the surface of the dry wiping roller may be coated with a layer of paint repelling material to increase the amount of reusable paint that falls into the tank under the combined effect of gravity and centrifugal force.

In FIG. 2 shows a second embodiment of a paint application system. In this embodiment, the reservoir 10 comprises a colorful chamber 11 with a paint spraying device 12 that sprayes the paint along the duct shaft 13. Due to the direction of rotation of the duct shaft, in this embodiment, the duct shaft knife can not be used as in the first embodiment, and therefore it becomes possible to directly use the engraved duct shaft 13 (either with an engraved surface or bearing an engraved shape), which simplifies the corresponding designs. Paint spraying is synchronized with the rotation of the duct shaft in order to avoid the application of ink in the non-engraved zone of the duct shaft and in the cavity of the shaft where the mold clamp is located. Above the colorful chamber 11 there is a wiping system with a wiping roller 8 and a doctor blade 9. Under the doctor blade 9 there are regenerating means, such as a tank 14 with pumping means 15 for supplying the regenerated ink to the ink supply circuit.

The printing machine of the embodiment of FIG. 2 is an indirect gravure printing machine. Accordingly, an engraved duct shaft, engraving of which corresponds to the engraving of the plate cylinder 16, transfers the ink from the engraving to the screen shaft 17 with embossed protrusions 18 corresponding to the parts on which the ink is applied, said embossed protrusions transfer the ink to the pick-up cylinder 19 before being transferred to the mold of the plate cylinder 16. The same pick-up cylinder 19 can receive inks of different colors from other ink application units, and the corresponding screen rolls are not shown in FIG. 2, but are similar to that which is present in the present ink application unit. The indirect ink application method within the intaglio printing method is known per se in the art, for example, from the aforementioned US patents Nos. 5062359 and 5899145.

In FIG. 2b shows a configuration option according to FIG. 2. In this embodiment, technical elements are denoted by the same reference numerals. This option is different from the configuration of FIG. 2 in that the pick-up cylinder 19 of FIG. 2 is absent, as a result of which a configuration is obtained involving direct application of paint. Accordingly, this option comprises a tank 10 with a colorful chamber 11 and a device 12 for spraying paint on the duct shaft 13. Under the spraying system there is a wiping system with a wiping roller 8, as well as a doctor blade 9 and regeneration means, for example, in the form of a tank 14 with a pump means for scraping paint 15.

An engraved duct shaft 13 with engravings corresponding to the engravings of the plate cylinder 16 transfers the ink from these engravings to the screen shaft 17 with embossed protrusions 18 corresponding to the parts on which the ink is applied, said embossed protrusions transfer ink to the shapes of the plate cylinder 16.

In FIG. 3 shows a configuration of a printing press with an ink coating system in accordance with the invention. In this configuration, the machine directly applies ink to the intaglio form. The paint application portion of this machine is that portion shown in FIG. 1, and its similar elements have identical designations. Accordingly, there is a reservoir 1, a duct shaft 2, a knife 3 for a duct shaft, the duct shaft 2 applying paint to the mold 6 of the selective rolling cylinder 5, which preferably carries an engraved shape 6, and a wiping roller 8 wiping the surface of the selective rolling cylinder 5. The doctor blade 9 scrapes the surface of the wiping roller 8, and the paint scraped in this way is regenerated in the tank 1.

The selective rolling cylinder 5 then applies paint to the transfer shaft 20 with a deformable surface so that the paint penetrates the engraving of form 6, said transfer shaft 20 transferring the paint to the screen shaft 21 with embossed protrusions 22, which then, in turn, apply paint directly to the mold by deposition plate cylinder 23 of the printing machine.

In a configuration involving direct application of paint, as shown in FIG. 3, it is necessary to use the transmission shaft 20 due to the direction of rotation of the plate cylinder 23.

In FIG. 4 shows yet another configuration of a printing press. In this configuration, the machine is an indirect gravure printing machine. The presented paint application system is similar to the paint application system of FIG. 1 or 3, while similar elements have identical designations. Accordingly, there is a reservoir 1, a duct shaft 2, a knife 3 for a duct shaft, the duct shaft 2 applying paint to the surface of a selective rolling cylinder 5 engraved or bearing an engraved shape 6, and a wiping roller 8 wiping the surface of the selective rolling cylinder 5. the knife 9 scrapes the surface of the roller 8 for wiping, and the paint scraped in this way is regenerated in the tank 1.

The selective rolling cylinder 5 then applies ink to the screen shaft 24 with embossed protrusions 25, which then in turn deposits the ink directly onto the pick-up cylinder 26. Then, the pick-up cylinder 26 applies ink by engraving 26 on the printing cylinder 28 of the printing press. In this example, the plate cylinder 28 has three shapes.

 The wiper assembly 45, which is itself known in the art, removes a minimal excess of ink from the engraving and from the surface of the molds.

In FIG. 4 shows a printable sheet 29, which is passed through a printing contact area 30 formed between the printing cylinder and the printing cylinder 31, as is usually the case in the gravure printing area. Of course, the system of the present invention is also suitable for roll presses.

The principle of indirect ink application in an intaglio printing machine is known per se in the art and is described, for example, in the aforementioned US Patents Nos. 4,516,496, 5,063,259 and 5,899,145, the contents of which are incorporated herein by reference.

The configuration of the press shown in FIG. 5 corresponds to an indirect gravure printing machine of four colors.

It contains four separate units 30, 31, 32 and 33 for applying paint, each of which has selective rolling cylinders 34-37, the engraving of which (or the forms that these cylinders bear) have the corresponding engraving 38 on the plate cylinder 39 in accordance with the principle of this inventions. Each application unit contains a duct shaft 2, a paint source and a knife 3 for the duct shaft. The paint is applied to selective rolling cylinders 34, 35, 36 and 37 and wiped with a roller 8 for wiping in the manner described above. Each of the selected rolling cylinders 34, 35, 36, and 37 receives ink of a different color and has engravings corresponding to the desired pattern on the shape of the plate cylinder 39, and the ink is transferred to the screen rollers 40, 41, 42, and 43 of each ink application unit.

In this configuration, the selective rolling cylinders 34, 35, 36, and 37 can only have a pattern whose engravings correspond to the color for which these selective rolling cylinders are intended. In yet another embodiment, all of the sample roll cylinders 34, 35, 36, and 37 can advantageously be engraved with the same pattern corresponding to the full pattern of the plate cylinder 39. In this case, the full pattern gets different colors on said sample roll cylinders 34, 35 , 36 and 37, and the choice of paint on each of the mentioned selective rolling cylinders 34, 35, 36 and 37 is carried out by the screen rolls 40-43, transferring only the desired paint to the picking cylinder 44. The advantage of this configuration is that everything is in Selective roll cylinders are identical, and this reduces manufacturing costs.

Then, the ink is transferred from each screen roll 40, 41, 42 and 43 to the pick-up cylinder 39. The wiper unit 45, which is itself known in the printing press industry, removes a minimal excess of ink from the engraving and from the surface of the mold.

After that, the actual printing process is carried out on the sheet 40, which passes into the printed contact zone 41 formed between the plate cylinder 39 and the printing cylinder 42, as is usually the case in the printing field.

The paint application system of the present invention has numerous advantages, such as simplicity and the important ink savings that it provides. Substantial amounts of paint are no longer wasted because proper wiping occurs at the level of the paint tank, rather than at the level of the plate cylinder, where all the colors of the paint are then mixed due to the wiping operation, so that reuse is not possible. In this case, only a minimal excess of paint is actually transferred to the plate cylinder, so that only a minimal amount of paint is wiped and lost.

Of course, the described embodiments are provided by way of non-limiting examples, and numerous changes are possible within the scope of the invention.

For example, in the machine configurations shown in FIG. 3-5, a paint application system according to FIG. 2.

In a preferred embodiment, the screen rolls are obtained in the usual way (in the form of a cylinder with screen forms or a solid cylinder). An advantage of the present invention is that the edges of the zone patterns of the screen rolls receive a minimum amount of ink — its thickness is a few microns. Therefore, the ink does not build up at the edges of the recessed part of the screen mold, and its washing becomes much easier for the operator.

In a preferred embodiment, the engraved selective roll cylinders of the present invention contain engravings that do not fully correspond to engravings of the printing form, but have lines characterized by:

a pattern identical to that of a printing plate (with the exception of the necessary mirror image, i.e., depending on whether the pattern engraved on the selected rolling cylinders should be a mirror image of the engraved pattern on the printing form);

the fact that they are larger than in engravings on a printed form, ensuring coordination with the tolerance of the position of the engraved lines on the printed form and compensation for this tolerance;

depth, in a certain ratio with the depth of the lines in printed form; in practice, this allows for engraving on selective rolling cylinders having a depth that, for example, is 30% greater than the depth of the engraving on the printing form, thus ensuring that an adequate amount of ink is transferred onto the printing form;

engraving using the same technology as for the printing plate.

In the case where some areas of the printing form have finely engraved patterns (with a depth of less than several tens of microns, in particular less than 10 microns), the presence of any engraving on a selective rolling cylinder (selective rolling cylinders) may not be necessary at all, but only engraving should be provided for deeper printing inks. In fact, the wiping system can be performed with the possibility of leaving a small amount of paint in the non-engraved areas of the corresponding selective rolling cylinder, and this amount of paint is sufficient to fill the paint with small engravings on the plate cylinder.

As for the patterns engraved on each sample roll cylinder, it should be noted accordingly that these engraved patterns, strictly speaking, are not identical to the corresponding patterns in printed form. Therefore, the definition of “appropriate”, used within the scope of the present invention to describe the relationship between engravings provided on a selective roll cylinder (selective roll cylinders) and on a plate cylinder, should be considered to mean a significant degree of similarity between the mentioned engravings, which is accompanied by slight differences in width depth and / or position. In addition, as mentioned above, the parts of the surface of the selective rolling cylinder (selective rolling cylinders) that correspond to fine engraving on the plate cylinder may not have any engraving at all, since the non-engraved zones of the selective rolling cylinder (selective rolling cylinders) may carry enough paint to fill her such small engravings.

In the embodiments shown in the drawings, various cylinder diameter ratios are provided. For example, in FIG. 3-5, the ratio of the diameters of the pick-up cylinder and the screen shaft is 3: 1, whereas in FIG. 2 this ratio is 2: 1. Of course, this should not be considered a limitation, but an illustration of various equivalent configurations that can be selected in accordance with the circumstances.

As mentioned above, all cylinders having an engraved surface may be directly engraved or may bear an engraved shape using clamping means.

Claims (24)

1. An intaglio printing machine designed to print sheets or rolls of securities, such as banknotes, checks, passports, identity cards and other similar objects, containing at least a feed unit, a printing cylinder (31; 42), a plate cylinder (16; 23; 28; 39), bearing at least one printing plate and a system for applying ink to the plate cylinder (16; 23; 28; 39), a printing contact area (30; 41) formed between the plate cylinder ( 16; 23; 28; 39) and a printing cylinder (31; 42), while the ink coating system for the printing machine is deep The first print contains at least a reservoir (1; 10) for applying paint to the surface of the engraved selective rolling cylinder (5; 13; 34, 35, 36, 37), which, in turn, applies paint to the surface of the plate cylinder ( 16; 23; 28; 39) by means of a screen roll (17; 21; 24; 40, 41, 42, 43) having relief projections (18; 22; 25) corresponding to engravings (27; 38), which are filled with paint, on said plate cylinder (16; 23; 28; 39), wherein said paint application system further comprises a wiping system (8, 9) for wiping a surface of said selective rolling cylinder and regenerating wiped paint in a tank (1; 10). 2. The machine according to claim 1, in which said reservoir (1) includes a duct shaft (2) for applying paint to the surface of a selective rolling cylinder (5; 34, 35, 36, 37). 3. The machine according to claim 2, in which the duct shaft (2) is coated with hard plastic or rubber. 4. The machine according to claim 1, in which the reservoir (10) is formed by a colorful chamber (11) with a device (12) for spraying paint, intended for applying paint to the surface of a selective rolling cylinder (13). 5. The machine according to claim 4, in which the spraying device (12) is synchronized with the rotation of the selective rolling cylinder (13) in order to avoid applying paint in the non-engraved zones of the selective rolling cylinder (13). 6. The machine according to claim 1, in which a selective rolling cylinder (5; 13; 34, 35, 36, 37) carries an engraved shape (6). 7. The machine according to claim 1, in which the wiping system includes a roller (8) for wiping. 8. The machine according to claim 7, in which the wiping system further comprises a doctor blade (9) for scraping the surface of the wiping roller (8). 9. The machine according to claim 7, in which the roller (8) for wiping is a roller for dry wiping. 10. The machine according to claim 7, in which the roller (8) for wiping rotates in the same direction as the selective rolling cylinder (5; 13; 34, 35, 36, 37). 11. The machine according to claim 7, in which the roller (8) for wiping is coated with hard plastic or rubber. 12. The machine according to claim 7, in which the roller (8) for wiping is coated with a material that repels paint. 13. The machine according to claim 7, in which the roller (8) for wiping is driven by an independent drive. 14. The machine according to claim 1, in which the screen shaft (17; 24; 40, 41, 42, 43) performs indirect paint application on the surface of the plate cylinder (16; 28; 39) by means of a pick-up cylinder (19; 26; 44) . 15. The machine according to claim 1, in which a selective rolling cylinder (5) applies paint to the screen shaft (21) by means of a transfer cylinder (20). 16. The machine according to claim 1, in which the wiping system (8, 9) is configured to leave a small amount of paint in the non-engraved areas of the selective rolling cylinder (5), and this amount of paint is sufficient to fill small engravings on the plate cylinder (16) ; 23; 28; 39). 17. The machine according to claim 1, in which the engraving of the selective rolling cylinder (5; 13; 34, 35, 36, 37) corresponds to the engraving (27; 38) in printed form and are characterized by a pattern that is an image or a mirror image of an engraved pattern in printed form. 18. The machine according to claim 1, in which the engraving of the selective rolling cylinder (5; 13; 34, 35, 36, 37) is larger than the engraving (27; 38) in printed form. 19. The machine according to claim 1, in which the engraving depth of a selective rolling cylinder (5; 13; 34, 35, 36, 37) is in a certain ratio with the engraving depth (27; 38) in printed form. 20. The machine according to claim 19, in which the engraving of the selective rolling cylinder (5; 13; 34, 35, 36, 37) has a depth that is approximately 30% greater than the depth of the engraving (27; 38) on the printing form. 21. The machine according to claim 1, in which the engraving of the selective rolling cylinder (5; 13; 34, 35, 36, 37) is engraved using the same technology as the engraving (27; 38) in printed form. 22. The machine according to claim 1, containing many systems (30, 31, 32, 33) for applying paint with corresponding tanks (2), wiping systems (8, 9), selective rolling cylinders (34, 35, 36, 37) and patterned shafts (40, 41, 42, 43), which apply paint to a common pick-up cylinder (44). 23. The machine according to item 22, in which each selective roll cylinder (34, 35, 36, 37) has only that engraved pattern that matches the color for which the transfer roll cylinders are intended. 24. The machine according to item 22, in which all of the sample roll cylinders (34, 35, 36 and 37) have the same engraved pattern, with each screen shaft (40, 41, 42, 43) transferring only the desired ink to pick-up cylinder (44).

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