EP0445661B1 - Ink transfer roller - Google Patents

Abstract

An ink transfer roller of a multicolour printing machine having a plurality of inking units (1, 31, 32), whose ink transfer rollers (1) have surface regions (10, 11, 12, 13) of different ink capacity. With few inking units (1, 31, 32) and blocks (B), printing areas (20, 21, 22, 23) of different ink saturation, e.g. with area and picture printing or security printing pattern, can be formed adjacently on the printing carrier (2). The printing machine is suitable for printing brochures, labels, packages, security-related papers and money. <IMAGE>

Description

The invention relates to an ink transfer roller of a multicolor printing machine with printing units according to the preamble of claim 1.

It is known from the document DE-30 46 257 A1 to arrange doctor rollers which can be placed on a scoop roller in a coating device on printing presses, by means of which a downstream metering roller is selectively supplied with paint, from which a metered amount of lacquer is applied by means of a doctor blade. This arrangement allows the paint to be applied in a certain thickness on an adjustable format width. The device is not suitable for an ink application with different ink density.

From document DE 33 36 374 C2 it is known to impress depressions or cells arranged in a grid in the surface of an ink transfer roller.

It is also from the US magazine Flexo, Vol. 10, No. 10, 45-50, known to burn the wells with a laser beam in the surface of an ink transfer roller.

For this purpose, it is known from DE-GM 87 10 726 to use distributing rollers with a structured surface in printing units, cups in the form of a pointed pyramid, a truncated pyramid or a spherical cap being knurled into the surface in a uniform pattern.

In the manufacture of such previously known ink transfer rollers, the aim is to cover the entire surface as evenly as possible with depressions, so that when used in a printing device the most uniform possible color saturation of the prints of the associated printing forms is achieved on the printed printing material. This means that more than 6 different inking units have to be used in the printing device for printing high-quality labels, packaging or advertising brochures, which often have an image part and a rich-colored lettering part, so smaller printing devices are not suitable for this.

It is therefore the object of the invention to create an ink transfer roller with which high-quality prints, in particular advertising material and security prints, with colors of different color densities can be produced, but only a small number of inking units of a multi-color printing machine should be necessary.

The solution consists in the features of the characterizing part of claim 1.

In a special embodiment of the inking roller, the surface areas of different ink capacities are arranged axially on the ink transfer roller, in each case as surface sections next to one another, adjoining one another. The assigned printing form is then designed in such a way that areas that require lean coloring are each assigned to one of the surface areas that has the lower color capacity and those areas that require rich coloring.
are each assigned to one of the surface areas with the higher color capacity.

In this way, it is possible to produce multi-color prints and multi-colored richly colored labeling fields in sections on a simple five or six printing unit printing machine. This has the additional advantage that only a correspondingly small number of printing plates have to be produced and set up on the forme cylinder.

The transition between the areas of different color capacity can be carried out abruptly from one circumferential line to the next, or a transition area can be designed with a constant increase or decrease in color capacity with a width suitable for an intended application. In this way, already existing printing forms can be printed in a new effect design by varying the saturation of the different colors and shadows in a simple manner, namely by suitable selection of the ink transfer rollers.

Another completely new application of such ink transfer rollers with different areas of different ink capacity results in the printing of value and security-relevant printing units, for. B. shares, banknotes, stamps or identity documents. For this purpose, the different surface areas can advantageously be designed as a security pattern, which can be introduced into the surface, for example, by a predetermined electronic control sequence of a burn-in laser. This security pattern overlays the print. It is practically impossible to fake. A close look at his Presence is easily possible with a magnifying glass by examining and assessing the individual color grid points with one another with regard to their relative size and according to their arrangement and the type of security pattern that they form. The individual colors can advantageously be applied with different security patterns by different rollers to increase security.

Fig. 1

zeigt einen Ausschnitt aus einem Druckwerk einer Druckmaschine;

Fig. 2

zeigt einen vergrößerten Ausschnitt aus den Oberflächenbereichen einer Farbübertragungswalze in Aufsicht;

Fig. 3

zeigt einen versetzten Schnitt nach Linie III-III durch Fig. 2, vergrößert;

Fig. 4

zeigt einen Tiefenschnitt in mit einem Laser hergestellte Oberflächenbereiche.

Fig. 5

zeigt eine Oberflächenstruktur einer Sicherheitsdruck-Farbwalze.

Advantageous embodiments of the invention are shown with reference to FIGS. 1 to 5.

Fig. 1

shows a section of a printing unit of a printing press;

Fig. 2

shows an enlarged section of the surface areas of an ink transfer roller in supervision;

Fig. 3

shows an offset section along line III-III through Fig. 2, enlarged;

Fig. 4

shows a depth section into surface areas produced with a laser.

Fig. 5

shows a surface structure of a security printing ink roller.

In Figure 1, an ink transfer roller 1 is shown schematically, the ink is supplied from an ink supply or doctor chamber 32 and which transfers the ink on a printing form B, which is mounted on a forme cylinder 31, in a surface line contact. The form cylinder 31 transfers this color to a printing material 2, the partially wraps around a printing cylinder 30 and further inking units, which are not shown, are arranged around its circumference. The ink transfer roller 1 has axially different surface areas 10, 11; 12, 13, which have different capacities for receiving the color. In each case, the surface areas 11, 12 with low capacity are assigned to those shape areas that each touch less to be saturated fields B1, B3, for example image fields, and those surface areas 10, 13 with high capacity are assigned to the shape areas of fields B0, B3, each are highly saturated with color and contain, for example, color bars and fields, ie full areas. Accordingly, imprints 21, 23, 20, 22 are carried out on the printing substrate 2 each in a more or less high color saturation, ie with a low or high color density. The illustration shows a printing form, each with the same use in the same orientation next to each other, so that the ink transfer roller 1 accordingly has two sections of high and two sections of smaller capacity alternately. The printing benefits are, for example, self-adhesive labels made of high-quality glossy paper, which are held releasably on a carrier tape.

FIG. 2 shows a plan view of the adjoining two surface areas 10, 11 of the ink transfer roller 1. The cups 40, 41 in the two surface areas 10, 11 are arranged in the same grid, which is designed with a row-like offset. Cross sections and widths W0, W1 of the cups 40, 41 are different, so that the ratio of the webs to the cups 40, 41 is also different for the same grid dimension. As a result, the ink transfer capacities of the surface regions 10, 11 are different.

FIG. 3 shows that depths T0, T1 of the wells 40, 41 are also different, so that the different capacities for the amounts of ink to be transferred also result accordingly in terms of area.

The configurations of the cups 40, 41 shown in FIGS. 2 and 3 correspond to embossments with a truncated pyramid with different impulses and different energies.

Similar are the different cups in Fig. 4, which are burned with a shaped laser beam into a hard ceramic roller surface K of different shapes. The width W0, W1 and the depth T0, T1 of the cells can be changed by suitably reversing the focusing of the beam and / or the intensity of the laser pulses. In addition, the grid spacing A0, A1 of the cells can be changed in a simple manner by controlling the pulse repetition frequency of the laser. The left and right image areas are each shown cut in the circumferential direction. All of these variations in the shape of the cells influence the color saturation and / or the color effect, so that the most varied of desired printing configurations can also be produced in the interaction of different colors.

FIG. 4 shows a depth section of a first laser L0 with a large width WO and a second laser L1 with a small width W1 but the same depth TO, T1. As a result, the roller produces approximately the same ink transfer ratio of the two areas until the end of the service life, which is determined by the depth TO, T1, in the event of wear occurring during use. The cells are one in the ceramic coating Branded metal roller M. Narrow cells L1 are introduced with a smaller grid spacing A1 than wide cells L0.

5 shows an enlarged top view of a surface section of a security ink transfer roller. The different surface areas BB, BG of different wells 40, 41 are nested one inside the other as security patterns in a small space. The design of the letters DB in the pattern is selected as an example for a stamp printing, the surface area BB having a larger color capacity than the surface area BG being designed as the basic area.

Claims (5)

1. Inking roller for a multi-colour printing press comprising a plurality of printing units, each incorporating a plate cylinder bearing a printing plate and the inking roller (1) in contact with said plate cylinder on a line around the circumference, and wells (40, 41) arranged in a grid being incorporated in the surface of said inking roller (1),
   characterised in that the inking roller (1) has at least two surface regions (10, 11, 12, 13, BB, BG) whose wells (40, 41) each have different capacities.
2. Inking roller according to claim 1, characterised in that the surface regions (10, 11, 12, 13) are axially contiguous surface sections with the different capacities.
3. Inking roller according to claim 1, characterised in that the surface regions (BB, BG) with different capacity take the form of a security pattern such that the depressions of one type constitute a predetermined pattern between the depressions of the other type.
4. Inking roller according to claim 1, characterised in that the wells (40, 41; L1, L0) of the surface regions (10, 11, 12, 13; BB, BG) have different widths (W0, W1), different depths (T0, T1) and/or different grid spacings (A0, A1).
5. Multi-colour printing press having at least one inking roller according to any of the preceding claims, characterised in that the wells (40, 41; L1, L0) of the various surface regions (10, 11, 12, 13) are burned into the surface (10, 11) using a laser torch unit and exhibit different widths and approximately the same depth.

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