HK1115014A - Ink fountain of a printing press - Google Patents

Description

Ink fountain of printing machine

Technical Field

The invention relates to an ink fountain of a printing press and an ink fountain roller for such an ink fountain.

Background

There are two types of ink fountain. In an ink fountain, one or more metering elements, such as a doctor blade or doctor blades (farbschaber), form a metering gap with the fountain roller. In another type, an ink fountain sheet, which is located between the metering element and the ink fountain roller, forms a metering gap with the ink fountain roller. Regardless of the ink fountain type, the components forming the metering gap that come into contact with the printing ink are subject to excessive wear when handling printing inks that are very abrasive. Very abrasive printing inks are empirically UV inks, high hiding white inks and matte oils. For reasons of abrasion, for example in UV inks, it is the tendency of such UV inks to polymerize and in this case harden in the form of particles due to the hydrodynamic pressure acting in the metering gap. The particles can grow such that they accumulate in the inlet of the metering gap as an abrasive layer.

DE 19914179 a1 describes an ink fountain sheet with filaments which increase the wear resistance. In one embodiment of the ink fountain sheet, the filaments are fixed to the carrier layer and covered by the cover layer in such a way that linear grooves extend between the filaments.

Disclosure of Invention

The aim of the invention is to provide an ink fountain which is sufficiently resistant to wear even when processing highly abrasive printing inks.

This object is achieved by the ink fountain according to the invention. The ink fountain of a printing press according to the invention comprises a member having a carrying surface for carrying printing ink and small recesses machined in the carrying surface.

In tests it has been established that particles, such as the UV ink particles mentioned, are flushed out of the metering gap by small recesses. The components that delimit the metering gap, such as the ink fountain sheet (farskastenfole) or the metering element, are no longer subjected to the abrasive action of the particles that accumulate in the metering gap, thereby resulting in an extended durability.

Unlike a linear groove, the opening of each small dimple has a rim that is closed around.

Further configurations of the ink fountain according to the present invention are exemplified in the following technical solutions.

In a further embodiment, the support surface forms webs between the small recesses, which webs occupy a higher area proportion than the small recesses. Accordingly, the total amount of the area of the tab per unit surface is greater than the total amount of the area of the small pocket.

In another further configuration, the small recess has an opening with an opening width that is less than 1 millimeter. If the individual small recesses have the shape of a hollow pyramid and the opening is thus square, the opening width is the side length of the square.

In another further configuration, the opening is circular and the opening width is a diameter. This geometry is obtained when the individual small pits have a spherical segment shape or a hollow cone shape.

In a further development, the small recess has a depth which amounts to at most 50% of the opening width. Accordingly, each small pit is at most as deep as half the width.

In another further configuration, the small pits are arranged in a regular grid. The small pits may be arranged, for example, in a checkerboard pattern.

In a further development, the component with the structure of small recesses is an ink fountain roller. Preferably the fountain roller is an ink fountain roller which is periodically in contact with the ink transfer roller.

The invention also relates to an ink fountain roller having a support surface for supporting printing ink and small recesses formed in the support surface, and to a printing press equipped with an ink fountain according to the invention or configured according to one of the further embodiments.

According to a further embodiment of the ink fountain roller, the small recesses formed in the ink fountain roller form a regular grid. However, in contrast to this preferred further configuration, the small recesses can also be produced in an irregular or random distribution in the circumferential surface of the fountain roller.

Drawings

Further structurally and functionally advantageous configurations of the invention emerge from the following description of a preferred embodiment and the figures thereof. The attached drawings show that:

FIG. 1 an ink fountain with an ink fountain roller, and

fig. 2 shows the surface structure of the ink fountain roller in fig. 1.

Detailed Description

Fig. 1 shows a detail of a printing press 1 for printing sheets by offset printing. The detail shows an inking unit which comprises an ink fountain 2 with an ink fountain roller 4 and an ink transfer roller 5. The ink fountain 2 contains a wedge-shaped reserve of printing ink 3 and is equipped with a metering device 6 which is divided over the printing width into individually controllable ink zones. During the printing operation, the distributor roller 5 is periodically applied to the fountain roller 4 in order to receive printing ink from the latter. The ink fountain roller 4 is provided with a macroscopic pit structure on the circumferential side, which is shown in an enlarged section in fig. 2.

Fig. 2 shows that the circumferential surface of the fountain roller 4 forms a support surface 7, which is formed by webs 8 that merge into one another in a mesh-like manner. In the circumferential surface, small recesses 9 are produced according to a grid 11, for example by laser engraving. The grid 11 has a grid width according to the center distance a of the dimples 9. The center distance A can take, for example, a value of 400 μm to 900 μm. The pit distance S, which can be measured from pit to adjacent pit, can for example take values of 200 μm to 600 μm, which corresponds to the width of the web 8. The dimples 9 each have an opening 10 whose diameter D can take values of 200 μm to 300. mu.m. The depth t of each dimple 9 takes a value of at least 10 μm.

For example, if the bearing or area ratio of the tab 8 or bearing surface 7 is about 76%, the center distance a is about 500 μm, the pit distance S is about 280 μm, and the diameter D is about 250 μm, wherein the depth t is about 15 μm.

The preferred embodiment is one in which the loading ratio or area ratio of the tab 8 or the bearing surface 7 is about 88%, wherein the center distance a is about 770 μm, the pit distance S is about 560 μm, the diameter D is about 275 μm, and the depth t is about 15 μm.

The small recesses 9 machined into the fountain roller 4 prevent the ink gap which exists between the fountain roller 4 and the metering device 6 or between this fountain sheet and the fountain roller 4 in the case of an interposed fountain sheet between the fountain roller 4 and the metering device 6 from becoming clogged with dirt particles and ink particles. The small recesses 9 prevent the printing ink 3 from accumulating in the ink gap and reduce the wear of the ink fountain roller 4, which would otherwise be caused by dirt particles or ink accumulations. This increases the reproduction accuracy of the adjustment of the metering device 6 and reduces quality fluctuations of the printed image. The duct roller 4 is particularly well suited for use in such cases: the printing ink 3 is a UV ink.

List of reference numerals

1 printing machine 9 Small pit

2 ink fountain 10 opening

3 printing ink 11 grid

4 ink fountain roller A center distance

5 ink transfer roller D diameter

6 measuring device S small pit distance

7 bearing surface t depth

8 contact piece

Claims (10)

1. An ink fountain (2) for a printing press (1) comprises a component having a support surface (7) for supporting printing ink (3) and dimples (9) formed in the support surface (7).

2. The ink fountain according to claim 1, wherein the carrying surface (7) constitutes tabs (8) located between the small recesses (9), which tabs occupy a higher area proportion than the small recesses (9).

3. The ink fountain according to claim 1 or 2, wherein the dimples (9) have an opening (10) with an opening width, said opening width taking a value of less than 1 mm.

4. An ink fountain according to claim 3, wherein the opening (10) is circular and the opening width is the diameter (D).

5. The ink fountain according to claim 3 or 4, wherein the dimples (9) have a depth (t) which is at most 50% of the width of the opening.

6. The ink fountain according to one of claims 1 to 5, wherein the dimples (9) are arranged in a regular grid (11).

7. The ink fountain according to one of claims 1 to 6, wherein the member is an ink fountain roller (4).

8. Ink fountain roller (4) for an ink fountain (2) of a printing press (1), wherein the ink fountain roller (4) has a carrying surface (7) for carrying printing ink (3) and dimples (9) formed in the carrying surface (7).

9. An ink fountain roller according to claim 8, wherein the dimples (9) are arranged in a regular grid (11).

10. Printing machine (1) having an ink fountain (2) according to one of claims 1 to 7.