WO2008151754A1

WO2008151754A1 - Printing device

Info

Publication number: WO2008151754A1
Application number: PCT/EP2008/004488
Authority: WO
Inventors: Christian Nelissen
Original assignee: Christian Nelissen
Priority date: 2007-06-11
Filing date: 2008-06-05
Publication date: 2008-12-18
Also published as: DE102007027382A1; DE102007027382B4

Abstract

The invention relates to a device for printing a substrate (10) in a high-pressure method, particularly a flexographic printing method. The device comprises a printing roller (10) with open regions (13) and one or more printing elements (12) that create the printed image (14), wherein the printing ink (15) can be applied to the printing elements (12). The device further comprises a counter roller (11). The substrate (10) can be guided over the counter roller during printing, wherein the substrate (40) is operatively connected in the respective current printing region (17) to the printing roller (10) and also to the counter roller (11). The printing roller (10) is provided with additional control printing elements (21) in addition to the actual printed image (14), forming a control wedge (20) for controlling the printing quality. Furthermore, an additional region is provided on the printing roller (10), comprising at least one support element (30) and printing a supporting printed image (31) on the substrate (10). The support element (30) is designed such that it causes the control printing elements (21) to be supported, opposing uneven deformation of the control printing elements created by local pressure differentials. The invention further relates to a method for printing a substrate (40) by means of a device, as mentioned above. For said method, it is essential that, while the control wedge (20) is pushed down, a region of the support element (30) is also operationally connected to the counter roller (11) at the same time.

Description

PRINTING DEVICE

The invention relates to a device according to the preamble of claim 1 and to a method for printing a substrate according to the preamble of claim 13.

Such devices are now widely used, for example in the field of printing on goods and packaging. These can consist of a wide variety of materials, such as paper, plastic film, metal foil and the like. In order to ensure a consistent quality of the print result, it must be constantly checked whether the print result is within the tolerance ranges of the specified target values.

For quality control so-called control wedges have been used for a long time, on which the printing inks are displayed in different print densities. Such control wedges are usually outside of the actual printed image so as not to disturb it.

In the high pressure process, a physical pressure is built up between the pressure roller and the counter roller to provide good transfer of the ink to the substrate. Since the rollers usually have a round cross-section, so only the current pressure range is always subjected to this physical pressure. However, since the printed image is not identical over the entire circumference of the printing roller, sometimes higher and sometimes lower physical pressures occur at the individual printing elements, depending on the area of the printing elements currently located in the current printing area. At higher pressures, however, it comes suggest that the pressure elements deform a little, usually in the elastic range. As a result, the pressure in the region of this pressure element can occupy a larger area than actually provided by the surface of the pressure element.

Such areas of increased pressure can also occur due to other external conditions, such as vibrations in the machine. If this inaccurate pressure then occurs in the area of the control wedge, the subsequent quality measurement is falsified by such inaccuracies. If you then adjust the setting of the printing press on this falsified measurement result, the quality of the generated pressure is impaired.

The object of the invention is therefore to provide a device in which control wedges can be made without affecting local pressure changes in order to check the quality of the print safely and reproducibly. Another object of the invention is to develop a method by which such control wedges are made reproducible. This is achieved by the characterizing features of claims 1 and 13, which have the following special significance.

On the pressure roller one or more areas are additionally provided, on which at least one support element is arranged. This support element prints a supporting pressure image on the substrate during the printing process. The or the support elements are designed so that they cause a support of the control pressure elements during the printing process, whereby they counteract caused by local pressure differences uneven pressure result of the control pressure elements. As a result, the control printing elements provide a uniform printed image, whereby accurate quality controls can be performed, which significantly improves the print quality. Also, this result is reproducible, since even temporarily occurring pressure differences, for example, by vibrations in the printing press barely play a role. The support member is easy and smooth to bring on the pressure roller when applying the printing elements on the surface with. It is particularly advantageous if the or the support elements are designed as Volltondruckelemente. For the realization of a full-tone element, namely, the support element must be fully in operative connection over its entire surface with the substrate located on the counter-roller. As a result, the support element can absorb as much of the resulting physical pressure and thus ensure a more even pressure distribution over the normal pressure elements and the control pressure elements.

In addition, a measuring device can be provided on the device, which measures the control wedge after the pressure in order to check the quality of the pressure. If the measurement result is not within the desired range, the press can then be adjusted accordingly.

Furthermore, the present invention teaches a method for printing a substrate by means of a device already described above. The essence of this method is that while the pressure of each control wedge at the same time always an area, at least one support element, is in operative connection with the counter roll. Precisely by this measure, it is then possible to minimize the inaccuracies in printing the control wedge caused by any local pressure deviations. For further details of this method, reference is made to the above-mentioned and to the following description.

In the figures, the invention is shown in one embodiment. Show it:

Fig. 1 shows the printing process in one, executed according to the invention

Contraption,

2 shows the development of a pressure roller according to the invention,

Fig. 3a - 3d several embodiments for the arrangement of control wedges and support elements. In Fig. 1, the principle of operation of the device according to the invention is shown. The printing roller 10 has printing elements 12 and free areas 13. The printing ink 12 is applied to the printing elements 12. The substrate 40, which is shown here as a continuous web, is guided over the counter roll 1 1. In the current printing area 17, the printing ink 15 is transferred from the printing elements 12 to the substrate 40 in order to produce the printed image 14 there. For this purpose, the pressure roller 10 moves in its direction of movement 16.

Fig. 2 shows the development of a pressure roller 10. Then the print image 14 is formed by the printing elements 12. Any print images are possible. The printed image 14 is designed here so that during the printing process in the current pressure range 17 is not always the same physical pressure between the surface of the pressure element 12 and the backing roll 1 1 is present. For quality control of the printing result, a control wedge 20 is provided. This consists in the present case of a series of fields 22 which are provided with different printing densities of the ink 15. It is customary here, for example, to provide a field with full tone and in each case one field with 75%, 50% and 25% printing density. Directly adjacent to the control pressure elements 21, which form the control wedge 20, a support member 30 is provided. This support element 30 is strip-shaped here and extends in the direction of the movement direction 16 of the pressure roller 10. This is particularly advantageous because it always occurs when a control pressure element 21 with the counter-roller 11 in operative connection, always a part of the support member 30 with the counter-roller. 1 1 enters into operative connection. The arrangement of the support member 30 directly adjacent to the control pressure element 21, a particularly good support of the control pressure elements 21 takes place, whereby occurring local differences in the physical pressure on the control pressure elements 21 is particularly effectively counteracted.

The control wedge 20 and the support element 30 are provided here in a seam region of the actual printed image 14. This is useful if the printed image is still cut out after printing and processed further. Not Required residues of the substrate 40 can then be easily recycled and reused. However, if the control wedge or the support element is located on these residues, recycling is often not or only very cumbersome possible, since for recycling color residues in the material bring undesirable properties. However, if one arranges these areas in an interface, where the material is later glued, welded or otherwise processed, for example, the remains of the substrate 40 can be easily recycled.

Various possible arrangements of support elements 30 and control wedges 20 are shown in FIGS. 3a to 3d. FIG. 3 a shows the arrangement of the support element 30 directly adjacent to one side 24 of the control wedge 20.

In an arrangement according to FIG. 3 b, two support elements 30 are provided, which enclose the control wedge 20 on both sides 24. As a result, the pressure distribution in the region of the control pressure elements 21 is particularly uniform. In such a case, it is sufficient if the width of the two support members 30 together is the same size as in a single support member 30 of FIG. 3a.

Another possibility is provided by FIGS. 3c and 3d. In Fig. 3c, two support elements 30 are also provided, which are, however, arranged at right angles to each other. Here they enclose a part of the control wedge 12 L-shaped. This arrangement is particularly advantageous if, for different print images 14, the areas with the control wedges 20 and the support elements 30 can shift by 90 °, depending on the exact structure of the pressure roller 10. Since it is advantageous, the support element 30 always in the direction of movement 16 to let the pressure roller 10, one is free in such an arrangement and you can use this regardless of the exact attachment of the printed image 14 on the platen roller 10 in any case. This works even better with an embodiment according to FIG. 3d, on which the control wedge 20 is surrounded by the support element 30 from all sides 24. Of course, it is also possible to provide several control wedge areas when using multiple printing inks 15. It is particularly favorable to provide a separate control wedge area 23 for each printing ink 15. Each of these control wedge areas 23 should have at least one own support element 30 in order to support the associated control pressure elements during the printing process. In most cases, a separate pressure roller 10 is also provided for each printing ink 15. Thus, each pressure roller 10 should have one or more support members 30 for the corresponding control wedge area 23. The support elements 30 on each pressure roller 10 should have the same shape and position, so that all supporting elements 30 in the finished printed image 14 form a common support pressure image 31. The control wedge areas 23 should then be best placed below or next to each other during final printing, as this greatly simplifies a measurement to check the print quality.

It should be understood that the embodiments illustrated herein are merely exemplary representations of the invention. This is not limited to this. On the contrary, further modifications are possible.

LIST OF REFERENCE NUMBERS

platen

backing roll

pressure element

outdoor Space

print image

printing ink

Movement direction of 10

Current pressure range

control wedge

Control pressure element

Fields of 20

Control wedge area

Page of 20

support element

Support print image

substratum

Claims

Patent claims

1. Device for printing a substrate (40) in a high-pressure process, in particular in the flexographic printing process,

with a pressure roller (10), the free areas (13) and one or more printing elements (12) which form the printed image (14), wherein on the printing elements (12) the printing ink (15) can be applied,

with a counter-roller (11), via which the substrate (40) can be guided during printing, wherein the substrate (40) in the respective current pressure region (17) with the pressure roller (10) and with the counter-roller (1 1) in operative connection occurs,

and wherein on the pressure roller (10) in addition to the actual printed image (14) additional control pressure elements (21) form one or more control wedges (20) for controlling the print quality,

characterized,

in that one or more areas are additionally provided on the pressure roller (10) which comprise at least one support element (30) which prints a support pressure image (31) on the substrate (40)

wherein the support element (s) (30) are designed to provide support for the control pressure elements (21) during the printing process, counteracting an uneven pressure result of the control pressure elements (21) caused by local pressure differences.

2. Apparatus according to claim 1, characterized in that the or the support elements (30) are strip-shaped and extend in the direction of movement (16) of the pressure roller (10).

3. Device according to one of claims 1 or 2, characterized in that the or the support elements (30) directly adjacent to the control pressure elements (21) are arranged.

4. Device according to one of claims 1 to 3, characterized in that at least two support elements (30) are provided, which are arranged on opposite sides (24) of the control wedge (20).

5. Device according to one of claims 1 to 4, characterized in that at least two support elements (30) are provided, which are arranged orthogonal to each other.

6. Apparatus according to claim 5, characterized in that the support elements (30) enclose at least a part of the control wedge (20) in an L-shape.

7. Device according to one of claims 1 to 6, characterized in that the or the support elements (30) are formed as Volltondruckelemente.

8. Device according to one of claims 1 to 7, characterized in that the control wedge (20) comprises a series of fields (22) which are printed with different printing densities.

9. Device according to one of claims 1 to 8, characterized in that when using a plurality of printing inks (15) Kontrollkeilbereiche (23) for each ink (15) are provided, wherein support elements (30) support each Kontrollkeilbereich (23) during the printing ,

10. The device according to claim 9, characterized in that for each ink (15) a separate pressure roller (10) is provided, wherein each pressure roller (10) has one or more support elements (30) for the corresponding control wedge area (23)

and that the support elements (30) on each pressure roller (10) have the same shape and position, so that a uniform support pressure image (31) is formed.

11. Device according to one of claims 1 to 10, characterized in that the KontroUkeil (20) and / or the support element (30) in a seam region of the actual printed image (14) are provided.

12. Device according to one of claims 1 to 11, characterized in that a measuring device is provided, which checks the quality of the pressure by measuring the control wedge (20).

13. A method for printing a substrate by means of a device according to one of the preceding claims, characterized in that

that during the pressure of the control wedge (20) always simultaneously a region of the support member (30) with the counter-roller (1 1) enters into operative connection.