WO2006045472A1

WO2006045472A1 - Unit for damping printing plates

Info

Publication number: WO2006045472A1
Application number: PCT/EP2005/011140
Authority: WO
Inventors: Richard Munz
Original assignee: Richard Munz
Priority date: 2004-10-21
Filing date: 2005-10-17
Publication date: 2006-05-04
Also published as: DE102004051342A1

Abstract

Disclosed is a unit (1) for damping printing plates of an offset printing press. Said damping unit (1) comprises a damping device (10) for spraying moisture onto at least one damping roller (9) which is used for transferring moisture to the printing plates. The damping device (10) is provided with a porous wall that is spaced apart from the damping roller (9) and is located between the damping roller (9) and at least one liquid outlet (22) which is directed towards the porous wall and the damping roller that is to be damped. Preferably, the porous wall of the damping device (10) is formed by the jacket (4) of a rotating hollow roller (11), which is porous in at least some sections, while the liquid outlet (22) is positioned within the hollow roller (11).

Description

Dampening unit for moistening printing plates

The invention relates to a dampening unit for moistening printing plates of an offset printing press, with a moistening device for spraying moisture onto at least one dampening roller, which serves to transfer moisture to the printing plates.

Offset printing uses the contrast of grease and water in the printing process. In this case, the surface of the pressure plate is such that the image-carrying layer assumes the print color (fat) and the non-imaged areas accept water.

In the printing press, the printing cylinder is moistened via a dampening unit before the dyeing process and then inked by means of the inking unit.

The parts moistened in this way repel the printing ink while the image-carrying layer removes the printing ink from the inking rollers and transfers them to a blanket cylinder which delivers the printed image to the paper.

There are various moisturizing techniques for moistening the printing plates.

Contact dampening units are known in which, starting from a scoop roller (dampening ductor) rotating in a dampening water tank, the dampening water film is transferred to the rotating printing plate cylinder via a roller arrangement. These dampening units have the disadvantage of the splitting back of the printing ink from the printing plate cylinder into the fountain bath, which makes this system expensive to maintain. There are also contactless dampening units in which the fountain solution is sprayed onto the dampening rollers via rotating elements. From the dampening rollers of the wet film is transferred to the printing plate cylinder.

In addition to this contactless dampening water transfer, spray dampening units are known in which nozzles are arranged over the width of the dampening rollers, which nozzles permanently spray dampening water onto the dampening rollers during the printing process. However, this technique has some disadvantages. The fountain solution must be very clean, otherwise the nozzles may become clogged. This immediately leads to dry spots on the printing plate cylinder, so that they accept printing ink and color stripes become visible on the paper. To ensure the necessary water quality, elaborate dampening water treatment plants are required. Also, the maintenance of the nozzle technology in practice is very expensive.

Object of the present invention is to provide a dampening unit of the type mentioned, with which the aforementioned disadvantages, ie in particular susceptibility to interference, Qualitäts¬ reduction of the printed product, are avoided and that ein¬ fold and compact in construction.

To achieve this object, it is proposed that the humidifying device has a porous wall which is at a distance from the dampening roller and has at least one liquid outlet directed towards the porous wall and the moisturizing roller to be moistened and the dampening roller.

The porous wall ensures that the one or more liquid jets impinging on one side, usually water, breaks down and as a spray mist on the other side of the porous wall escape. Such a device does not require fine spray nozzles, which can be clogged by contamination particles in the liquid, so that quality reductions of the printed product are avoided by uneven spray application. In addition, expensive wet water treatment systems are therefore not required.

According to one embodiment of the invention, the porous wall can be movably arranged relative to the liquid outlet and coupled with a movement drive. As a result, closures of the pores or of the fine through-openings of the porous wall can be avoided, since contaminating particles can not settle.

A further embodiment of the invention provides that the porous wall is arranged at an angle deviating from 90 ° relative to the longitudinal axis of the liquid outlet.

Experiments have shown that this refinement of the spray can be achieved.

A preferred embodiment of the invention provides that the porous wall of the moistening device is formed by the at least partially porous shell of a rotating hollow roller and that the liquid outlet is located inside the hollow roller.

The rotating hollow roller in particular has the advantage that a punctual application of ink on the hollow roller does not yet lead to maculature, because such punctiform ink deposits are compensated by the surrounding regions of the porous hollow roller wall.

Expediently, within the rotating hollow roller spaced apart from the dampening roller, there is preferably a spray tube extending approximately over the length of the hollow roller, preferably with several onto the porous roll shell and the to-be-conveyed moist dampening roller directed liquid outlet openings provided.

The length of the spray tube is dimensioned so that the adjacent wetted roller can be moistened uniformly over its entire length.

An alternative embodiment of a dampening unit for achieving the stated object provides that the moistening device has a porous wall which is at a distance from the dampening roller and which dips into a liquid bath with a partial region and a blower device with a porous wall and the moist roller to be moistened gas outlet is provided. The structure of the porous wall is in this case designed so that it absorbs fountain solution when immersed in the liquid bath (dampening water bath), so that the capillaries are filled with fountain solution. With the blowing device, the dampening water contained in the capillaries of the porous wall is blown out and transferred to the dampening rollers.

It is preferably provided that the moistening device has as a porous wall a rotating hollow roller spaced apart from the dampening roller with an at least partially porous roll shell, that the hollow roll is immersed in a liquid bath with a partial circumference of its porous shell and that inside the hollow roll and above the liquid level, the blowing device is provided with a directed to the porous roll shell and the moistening wet roller gas outlet. The rotating roll shell absorbs fountain solution when it is immersed in the liquid bath (dampening water bath), so that the capillaries of the roll shell are filled with dampening water when they are immersed in the fountain solution level and closed. The above- The dampening solution stored in the capillaries of the roll shell is then transferred to the dampening rollers by means of the blowing device located inside the roll shell.

Expediently, a tubular, preferably approximately over the length of the hollow roller relationship or the porous region of the roll shell extending Blas¬ chamber is provided with at least one forming a Blasrakel flat nozzle or with a plurality of gas outlet openings within the hollow cylinder. The width of the flat nozzle or the arrangement of the gas outlet openings is dimensioned so that the adjacent wet roller (s) are uniformly moistened over their entire length.

The control of the dampening water quantity to be transferred can advantageously be effected by changing the rotational speed of the hollow cylinder. In this case, the exiting air stream (blowing pressure) can remain constant while the rotational speed of the roller is varied.

Preferably, the porous wall or the porous roll shell of the rotating hollow roller made of metal, polyamide or plastic and is in particular designed as a fabric or tissue-like with a fine fabric structure. On the one hand, such a structure enables a fine splitting of a spray jet into a fine spray jet, whereby the capillaries of the porous wall can be dimensioned so large that clogging by fine dirt particles is avoided. Accordingly, no elaborate dampening water treatment plants are required. On the other hand, the structure of the porous roll mantle makes it possible to take up a sufficient amount of liquid and to transport it in front of a blowing device, where the liquid is then blown off onto the wetting roll as a spray jet. Additional embodiments of the invention are set forth in the further subclaims. The invention with its essential details with reference to the drawings is explained in more detail below.

It shows something schematized:

1 shows a cross section of a first embodiment of a dampening unit,

2 shows a cross section of a second embodiment of a dampening unit,

3 shows a front view of the dampening unit shown in FIG. 2 with a hollow cylinder shown cut longitudinally, FIG.

Fig. 4 shows a cross section of a further, in principle Fig.1 corresponding embodiment of a dampening unit, but here with a porous wall instead of a hollow cylinder and

Fig. 5 shows a cross section of a further, in principle Fig.2 corresponding embodiment of a dampening unit, but here with a porous wall instead of a hollow cylinder.

A first embodiment of a dampening unit 1 is shown in FIG. It is used for the indirect moistening of printing plates of an offset printing machine by means of a dampening roller 9, which is sprayed by a moistening device 10 with water or the like moisture. The dampening roller 9 then serves for Transfer of moisture to the printing plates. The moistening device 10 has a to the dampening roller 10 spaced, rotating hollow cylinder 11, which has an at least partially porous roll shell 4. Within the hollow roller is a liquid outlet 22, which is directed to the porous roll shell 4 and the moistening roller 9 to be moistened.

The liquid outlet may be provided on a spray tube 12 which extends approximately over the length of the hollow cylinder 11 and which has lateral liquid outlet openings in its longitudinal course. At one end of the spray tube 12, a connection 23 for supplying water is provided.

The roll shell 4, on which the water impinges on the inside, preferably consists of a fine fabric structure of metal, polyamide (nylon) or plastic fabric and is structured so that impinging jets of water are decomposed into a fine spray or spray jet 15, which is deposited on the dampening roller 9 reflected. Instead of a rotating hollow cylinder 11 with a porous roll shell 4 could be arranged between the liquid outlet 22 and the dampening roller 9 in the simplest case, a stationary porous wall. However, the rotating hollow cylinder 11 has the advantage that water is continuously applied to new wall sections, so that, inter alia, punctual ink deposits are avoided in the surroundings from the usually existing color mist. This can also be achieved, as will be described below, with a porous wall which is movable.

FIGS. 2 and 3 show another embodiment of a dampening unit 1a. This moistening device 10a likewise has a rotating hollow roller 11 spaced apart from the dampening roller 9 and having a roll shell 4 which is at least partially porous. However, this hollow cylinder 11 is immersed with a partial circumference of its porous shell 4 in a liquid bath 13 and within the hollow cylinder 11, a blowing chamber 5 is provided above the liquid level 3 with a directed to the porous roll shell 4 and the dampening roller 9 to be humidified gas outlet opening 7. The porous roll shell 4, which is preferably formed by a fabric structure, is such that it absorbs dampening water when immersed in the dampening water level, whereby the capillaries of the roll shell are closed and filled with dampening water and the water is then stored up to the blow-out point , In order to avoid the escape of the dampening solution from the roll shell by the rotation (centrifugal force), the structure of the roll shell is designed so that it absorbs so much water that the demand (level of experience) is covered without requiring a high speed is.

The arranged within the hollow cylinder 11 Blaskammer 5 is tubular and preferably extends approximately over the length of the hollow cylinder 11 (see also Fig.3). In the exemplary embodiment, it has a flat nozzle 6 forming a blowing blade whose gas outlet opening is arranged close to the inner side of the porous roll shell 4. Instead of a flat nozzle 6, a plurality of gas outlet openings can be provided distributed over the length of the blow chamber 5. The distance between the gas outlet opening 7 and the porous roller shell 4 can be a few tenths of a millimeter down to a few millimeters, preferably about 0.5 mm.

The gas outlet opening 7 of the blowing chamber 5 is also located close to the liquid surface 3 at a distance of, for example, 10 mm. The liquid picked up by the porous roll mantle 4 is conveyed by rotation of the hollow roll 11 in the direction of the arrow Pf.1 along the shortest path in front of the gas outlet opening 7 and there from that from the flat die 6 blown out air stream and transferred as spray 15 to the dampening roller 9. The air turbulence when Durch¬ passes through the fabric structure of the porous roll shell 4 ensures a fine, uniform distribution of water to a water mist, the corresponding evenly distributed wetting the surface of the fountain roller.

The control of the amount of dampening water to be transferred is done in such a way that the exiting air flow (blowing pressure) is kept constant, while the rotational speed of the

Roller is variable. If the roller rotates faster, correspondingly more dampening water is blown onto the dampening rollers. If more or less dampening water is required by changing the speed of the printing press, the rotational speed of the hollow cylinder 11 is increased or slowed down. In this way you can react very quickly, which is very important for the printing process.

The liquid of the liquid bath 13 is supplied via a liquid connection or an input 27.

It can also be seen in FIG. 3 that a drive motor 20 for the rotation of the hollow cylinder 11 is attached laterally to the housing 16. Opposite is the feed 21 for blowing air.

As can be seen in FIGS. 1 and 2, the hollow rollers 11 are each located within a chamber 2, which forms a wet cell and which faces the dampening roller 9, a slot-like outlet opening 14 (FIGS. 2 and 3) for the spray jet 15. has. The hollow rollers 11 are thus enclosed up to the outlet opening 14 and thus are well protected against contamination. The wet cell (chamber 2), for its part, is arranged inside a housing 16 which is open on one side to the dampening roller 9, whose upper side 17 and lower sides 18 extend close to the dampening roller 9 and thus form a shield for the spray jet and also a dirt seal ,

The underside 18 of the housing 16 is formed as a collecting trough for excess fountain solution, which is fed to a liquid keitsablauf 19.

In the embodiment according to Figures 2 and 3, the excess fountain solution (dripping water) is returned by means of a hose in a liquid circulating system.

Figures 4 and 5 show embodiments of dampening units 1b, 1c, with moistening devices 10b and 10c, in which instead of a hollow cylinder 11, as shown in Fig. 1 to 3, a flat, porous wall 24,24a is provided.

The embodiment of the dampening unit 1b according to FIG. 4 is constructed in principle like the dampening unit 1 shown in FIG. 1, but instead of the hollow cylinder 11 it has a porous wall 24 between one of the dampening rollers 9 directed liquid outlet 22 and the dampening roller 9 is arranged. The porous wall 24 is held by a frame 25. In particular, if the porous wall 24 is not intrinsically stable, for example, if it is made of fabric or fabric-like ausge¬ forms with a fine fabric structure, this frame can serve as a clamping frame. He can attack on opposite sides or circumferentially on the porous wall 24. The porous wall 24 can be moved relative to the liquid outlet 22 by a movement drive, not shown here, in order to constantly open up new wall sections with liquid, so that dirt particles do not settle and thereby clog the fine passage openings can. The movement can be a float or a circling motion.

It is still clearly visible in FIG. 4 that the porous wall 24, with its flat side, is not arranged at right angles to it but at a different angle to the longitudinal axis of the liquid outlet 22. Due to the inclination, the decomposition of the liquid jet emerging from the liquid outlet or outlets 22 into a fine spray mist is promoted or a refinement of the spray mist is achieved. The skew angle can be varied according to the requirements.

The remaining components of the dampening unit 1b correspond to those of the - dampening unit 1 in Figure 1 and are marked with the same reference numbers ge.

The embodiment of the dampening unit 1c according to FIG. 5 is constructed in principle like the dampening unit 1 shown in FIG. 2, but instead of the hollow roller 11 has a porous wall 24a which dips into a liquid bath 13 with a partial area. By means of a blowing device which has a directed onto the porous wall 24 and the dampening roller 9 to be humidified gas outlet 7, the capillary sucked, located in the porous wall 24a liquid is blown out and transferred to the dampening roller 9 as a fine spray mist. As can be seen in the exemplary embodiment, the porous wall 24a can be suspended on the upper side on a holder 26 and can dip into the liquid bath 13 with its lower end. Again, a movement of the porous wall 24 may be provided relative to the or the gas outlet openings 7 in order to avoid clogging by dirt particles. For such a movement, the holder 26 may be formed as a guide rail.

The porous wall 24a shown in Figure 5, as the porous wall 24 of the embodiment of Figure 4, arranged obliquely in this case, obliquely to the longitudinal axis of the gas outlet 7, in order to achieve a finer spray. The remaining components of the dampening unit 1 c correspond to those of the dampening unit 1a in Figure 2 and are marked with the same reference numerals.

The dampening units 1, 1a, 1b, 1c according to the invention have a compact design and are relatively small. They can be fastened laterally to holders via quick-release fasteners in the printing press. For removal, only the connections of the fountain solution supply and return hose and in the case of the embodiment according to FIGS. 2 and 3 of the blown air connection 21 and the quick-release closures have to be loosened.

/Claims

Claims

claims

1. dampening unit (1) for moistening printing plates of an offset printing machine, with a moistening device (10) for spraying moisture onto at least one dampening roller (9), which serves to transfer moisture to the printing plates, characterized in that the moistening device ( 10.10b) a porous wall (4, 24) spaced from the dampening roller (9) between at least one liquid outlet (22) and the dampening roller (9) directed onto the porous wall (4, 24) and to the dampening roller (9) to be moistened. having.

2. dampening unit according to claim 1, characterized in that the porous wall (4,24) relative to the liquid outlet

(22) is movably arranged and coupled to a movement drive.

3. dampening unit according to claim 1 or 2, characterized in that the porous wall (24) deviating in a 90 °

Angle is arranged relative to the longitudinal axis of the liquid outlet (22).

4. dampening unit (1) according to one of claims 1 to 3, characterized in that the porous wall of the Befeuchtungsein¬ direction (10,10b) by the at least partially po¬ rösen jacket (4) of a rotating hollow roller (11) is formed and the liquid outlet (22) is located inside the hollow roller (11).

5. dampening unit according to claim 4, characterized in that within the to the dampening roller (9) spaced ro¬ tierenden hollow roller (11) is preferably about about the length of the hollow roller extending spray tube (12) is provided with preferably a plurality of on the porous roll shell (4) and to be moistened dampening roller (9) liquid keits-outlet openings (22).

6. dampening unit (1 a, 1 c) according to the preamble of claim 1, da¬ characterized in that the moistening device (10 c) to the dampening roller (9) spaced, porous wall (24 a) which with a partial area in a liquid bath (13 ) and that a blowing device is provided with a gas outlet (7) directed onto the porous wall (24a) and to the dampening roller (9) to be moistened.

7. dampening unit according to claim 6, characterized in that the porous wall (24a) relative to the gas outlet (7) movably arranged and is coupled to a movement drive.

8. dampening unit according to claim 6 or 7, characterized in that the porous wall (24a) is arranged in a deviating from 90 ° angle relative to the longitudinal axis of the gas outlet (7) ange¬.

9. dampening unit (1a) according to one of claims 6 to 8, characterized in that the moistening device (10a) as a porous wall to the dampening roller (9) spaced ro¬ tierende hollow roller (11) with an at least partially porous roll shell (4 ), that the hollow roller with a partial circumference of its porous shell immersed in a liquid keitsbad (13) and that within the hollow roll (11) and above the liquid level, the Blasein¬ direction with a on the porous roll shell (4) and the moisturizing roller (9) directed to be humidified is provided.

10. dampening unit according to claim 9, characterized in that within the hollow roller (11) has a tubular, preferably approximately over the length of the hollow cylinder extending blow chamber (5) with at least one a Blasrakel bil¬ forming flat nozzle (6) or with several Gas outlet openings are provided.

11. dampening unit according to claim 9 or 10, characterized gekennzeich¬ net, that the gas outlet opening (s) (7) of the blow chamber

(5) is arranged close to the inside of the porous roll mantle (4) and that the distance is a few tenths of a millimeter up to a few millimeters, preferably about 0.5 mm.

12. dampening unit according to one of claims 9 to 11, characterized ge indicates that the gas outlet opening (s) (7) of the puffer chamber (5) is arranged close to the liquid surface at a distance of for example 10mm and that the direction of rotation of the hollow roller (11 ) is provided for direct För¬ tion of liquid in front of the gas outlet opening (s) (7) of the puffer chamber.

13. dampening unit according to one of claims 9 to 12, characterized ge indicates that the rotational speed of the Hohl¬ roller (11) is variable for controlling the amount of moisture to be transferred liquid.

14. dampening unit according to one of claims 1 to 13, characterized ge indicates that the porous wall (24,24a) relationship, the porous roll shell (4) of the rotating hollow roller (11) made of metal, polyamide or plastic and is in particular designed as a fabric or tissue-like with a fine fabric structure.

15. dampening unit according to one of claims 1 to 14, characterized ge indicates that the hollow roller (11) or the porous wall (24,24a) within a chamber (2) be¬ find as a wet cell, the dampening roller (9) facing a Austritts¬ opening (14) for at least one spray jet.

16. dampening unit according to claim 15, characterized in that the chamber (2) (wet cell) within a housing (16) is arranged, whose upper and lower sides (17,18) extend to close to the dampening roller (9) and that the housing (16) is formed on the underside as a collecting trough for über¬ schüssiges dampening water.

17. Dampening according to claim 15 or 16, characterized gekennzeich¬ net, that the chamber (2) (wet cell) has a liquid effluent (19) for itself in the wet cell accumulating liquid keit.

18. dampening unit according to one of claims 1 to 17, characterized ge indicates that it has snap closures for releasable connection with the printing press.

/Summary