EP2242651A2

EP2242651A2 - Rotary flat-bed printing machine

Info

Publication number: EP2242651A2
Application number: EP09710271A
Authority: EP
Inventors: Axel Hauck; Jörg Heuschkel; Rüdiger Böhm
Original assignee: Heidelberger Druckmaschinen AG
Current assignee: Heidelberger Druckmaschinen AG
Priority date: 2008-02-12
Filing date: 2009-01-28
Publication date: 2010-10-27
Also published as: CN101888929B; CN101888929A; WO2009100817A3; WO2009100817A2; US20110011289A1

Abstract

The invention relates to a rotary flat-bed printing machine having an inking unit with a plurality of inking rolls and a dampening unit with a plurality of dampening rolls, wherein one of the dampening rolls (34) has a porous surface from which the dampening agent exits. In the dampening agent flow, between the dampening roll (34) having the porous surface and the plate cylinder (6a), at least two further rolls (35, 37) are arranged.

Description

Rotary lithographic printing press

description

The invention relates to a rotary flat printing machine with an inking unit, which has a plurality of inking rollers, and with a dampening roller, from the porous surface of the fountain solution emerges.

Rotary printing machines, so for example, roller or

Sheet-fed offset printing presses, usually have in each printing unit an inking unit with multiple inking rollers that direct the color flow from the ink reservoir, the ink fountain to the offset printing plate on the plate cylinder, this even, possibly laterally rub etc. In addition, in the so-called wet offset a dampening unit is required, the offset printing on wets the hydrophilic areas of the printing plate and ensures that the printing plate takes no color there. Such dampeners are usually constructed according to the scoop principle, d. H. a so-called dip roller partially immersed in a water tank and from its surface is transported by further rollers of the water film to the voltage applied to the plate surface dampening roller.

In addition, so-called spray dampening units are known in which instead of the water box and the dipping roller, a spray bar is used, with which on the surface of one or more dampening rollers a water film is sprayed.

Furthermore, it is known from JP 05-064872 A and WO 2006/047997 known to use so-called membrane rolls in the dampening unit, d. H. Dampening agent rolls from whose porous surface the dampening solution emerges. These porous fountain solution rollers are employed according to the prior art directly to the dampening roller u. a. because it has an elastic roll shell, while the porous membrane roll is made of

Sintered metal is and in this way a good for the removal of dampening solution adjustable gap between the rollers results, which would not be the case of a contact of two hard rolls.

In this arrangement, inhomogeneities of the dampening solution on the roll surface can be compensated poorly due to the short transmission path to the printing plate. Finally, there is the problem that the dampening roller to a certain extent also returns color from the printing plate to the porous fountain solution roller so that it becomes dirty and the pores are clogged with paint. This problem is also in the o. G. JP 05-064872 was addressed.

It is the object of the present invention to reduce or avoid the problems associated with the use of porous fountain solution rollers.

This object is achieved with the features specified in claim 1.

According to the invention, at least two further rollers are arranged between the porous fountain solution roller and the plate cylinder.

In a first embodiment, the porous dampening solution roller is employed via at least one further roller, which is interposed in the dampening solution flow, to the application roller of the dampening system contaminated with paint. This makes it possible, this intermediate roller (s) with a at least in operation, d. H. to provide in the moistened state ink-repellent surface. On the way, the return transport of ink from the inking unit to the surface of the porous dampening roller can be reduced or prevented. It is of course also possible and appropriate, the porous

Fountain solution roll even with a paint-repellent surface at least during operation.

According to a second embodiment of the invention, the porous fountain solution roller is assigned to the inking unit and employed at least during the pressing either directly or via one or more intermediate rollers to one or more of the inking unit rollers. In this arrangement, the otherwise required, separate dampening unit can be completely eliminated, so that at the periphery of the plate cylinder additional space is free, which can be used, for example, to integrate there a washing device for the plate cylinder. Nevertheless, the function of the dampening unit is ensured because the dampening water emulsifies in the color transported by the inking unit and thus reaches the plate cylinder or the printing plate in this way.

It is expedient to employ the porous dampening solution roller on the or one of the inking rollers of the inking unit optionally via an intermediate roller, in inking units with three to four applicator rollers best seen in the printing gap from in

Direction of rotation of the plate cylinder first of the inking rollers. This ensures that the plate is already sufficiently moistened when the other inking rollers "come into play." Accordingly, toning of the non-printing areas of the offset plate is avoided.

However, it is also possible to make the porous dampening roller directly or indirectly to a roller in the ink flow of the inking unit. Then the dampening solution can be emulsified more homogeneously into the paint.

The best position for the introduction of dampening solution in the inking unit depends on the type of inking unit and its specific structure and can be found by appropriate pressure tests.

In so-called short inking units (anilox inking units) in which the ink is metered with a doctor blade and an anilox roller, usually only a single

Ink application roller provided. Here it is expedient to employ the porous fountain solution roller optionally via one or two intermediate rollers to the inking roller. Especially in connection with anilox inking units, the advantages of the porous dampening solution roller can be used particularly well with regard to optimum utilization of the installation space in the printing unit. Although the volume flow of dampening water, which emerges from a porous dampening solution roller, depends on the internal pressure in the porous fountain solution roller, but otherwise zeitinvariant, ie constant, regardless of how fast is currently being printed, ie how many plates must be moistened per unit time. It is therefore expedient to provide switching and / or adjusting elements, with the aid of which the pressure of the dampening solution in the interior of the porous fountain solution roll is adjustable. Advantages also include a temperature of the fountain solution, which is fed to the porous fountain solution. Because it has been found that the temperature of the fountain solution supplied to the plate should not be too high, should be below the machine temperature, in order to obtain stable production conditions. This is particularly important in the event that should be printed with as little or no alcohol in the dampening water, so where the cooling effect of the otherwise evaporating isopropyl alcohol is less or eliminated.

In addition, the porous fountain solution roller offers the possibility of metering the fountain solution zone by zone, d. H. to let out in different amounts from the roll shell in the axial direction. This makes it possible to stably print even difficult print jobs with a very inhomogeneous distribution of the subjects on the printing plates. This is achieved with the fact that the interior of the porous fountain solution roller consists of individual segments and the pressure in the segments is independently adjustable.

If, in spite of the countermeasures described at the outset, ink adheres to the surface of the porous dampening solution roller, this leads to the fact that the water outlet at the places covered with paint is partially suppressed. In addition, dampening agent increases in the neighboring areas from the porous dampening roller, resulting in over-moistening of the printing plate at the non-image areas. This effect is caused by a dampening water flow in the axial direction within the porous carrier material of the dampening solution roller. To avoid this, it is therefore expedient to give the porous carrier material of the dampening solution roller an anisotropic structure which prevents a dampening water flow parallel to the roll surface. The same effect occurs when the membrane with the narrower pores, which is the primary flow resistance compared to the porous carrier material of the roller, not inside, but externally applied to the hollow cylindrical support material of the roller. In such a configuration, the surface of the porous dampening solution roller can also be better rid of paint residues by z. B. in washing cycles the dampening roller is subjected to increased internal pressure.

Further advantages of the invention will become apparent from the following description of embodiments with reference to Figures 1 to 12 of the accompanying drawings.

Figure 1 shows a four-color sheet-fed offset printing machine, which is equipped with conventional film dampening units.

Figure 2 shows a section through the inking unit 8a in the printing unit 7a (roller pattern) according to a first embodiment of the

Invention.

Figure 3 shows a slightly modified compared to Figure 2

Embodiment of the invention.

FIG. 4 shows the roller scheme of an embodiment of the invention for an anilox inking unit.

Figure 5 shows a schematic diagram of the fountain solution cycle for the supply of porous rolls, z. B. roller 34 in Figure 2.

FIG. 6 shows an alternative embodiment of the invention

Dampening water circuit according to FIG. 5.

FIG. 7 shows a section through the inking unit 8a in the printing unit 7a

(Rolling scheme) according to a second exemplary embodiment of the invention. FIG. 8 shows an alternative embodiment of the inking unit

Figure 2, also in section.

FIG. 9 shows the roller diagram of a further exemplary embodiment of the invention

Invention for an anilox coloring work.

Figure 10a shows a suitable for the embodiments of Figure 2 to 9 porous fountain solution roller (membrane roller) in section.

Figure 10b + c show the structure of the porous roll shell of the roller of FIG

10a in two slightly different variants on an enlarged scale.

FIG. 11a shows a porous fountain solution roller constructed differently in comparison to FIG. 10a.

FIG. 1b shows the structure of the roll mantle of the roll from FIG. 1a on an enlarged scale.

FIG. 12a is a schematic diagram of a segmented porous fountain solution roller.

FIG. 12b shows the roller from FIG. 12a in partial section in a plane containing the roller axis.

The sheet-fed offset offset printing machine 1 in series construction shown in FIG. 1 has a feeder 2 in which the unprinted paper stack 3 is located, as well as four printing units 7a-d for the four primary colors black, yellow, magenta and cyan. On the fourth printing unit 7d follows the boom 12 of the printing press. In it grabber bridges run by means of a chain guide. These gripper bridges take over the printed sheet and feed it to the stack of sheets where it is deposited. The printing unit 7a has a counter-pressure cylinder 4a, a blanket cylinder 5a and a plate cylinder 6a, on which the respective pressure plate is clamped. The same applies to the other three printing units 7b-d. The printing plates are dyed with inking units 8a-d, whose rollers cover a large part of the cylinder circumference of the plate cylinder. To the respective inking unit, z. B. 8a, close the four rollers of the dampening unit 9a, of which the fountain roller promotes the fountain solution from a water tank 10a. With 1 Ia, the cloth washing device for the blanket cylinder 5a of the printing unit 7a is designated.

The illustrated in Figure 2 combined ink fountain unit according to the invention consists of a knife ink fountain 13, a ductor roller 14, four inking rollers 28, 29, 30 and 31, with which the printing plate is inked on the cylinder 6a, and a number of other rollers 15 to 27, from which the ink is removed from the ductor 14, distributed and triturated and then fed to the applicator rolls. With 15 of the clockwise between the ductor 14 and the roller 21 oscillating color lifter is designated. The rollers 21, 22, 23 and 24 are traversing distributor rollers, the drivers 23 and 24 being cooled. The ductor 15 and the rollers 16, 17, 18, 19, 20 are provided with a rubber jacket, as are the four inking rollers 28 to 31, while the rollers 27, 26 and 25 are steel rollers.

At the dampening form roller 37, a chrome-plated distributor roller 36 is employed. This serves to even out the fountain solution film of the applicator roll 37. The rough chromium layer is hydrophilic, but also tends to take on color when there is no water film on the surface of the distributor roller 36.

To the fountain solution roller 37 is also indirectly via an intermediate roller 35, a porous dampening roller 34 employed. This dampening roller 34 is, as indicated by the supply line 66a and the return line 86a, connected by means not shown in detail on the bearing journal of the roller 34 to a dampening solution circuit. The fountain solution supplied via the line 66 a floods the interior of the roller 34 and passes with a corresponding overpressure through the porous roll shell, reaches the intermediate roll 35 and is from this to Dampening solution roller 32 transported. The structure of the porous fountain solution roller 34 may be as described in the aforementioned WO 2006/047997, ie, the porous dampening roller 34 may have a two-part construction with a membrane fitting inside the porous roller body 34, which has pores with a smaller diameter than the pores However, it is also possible to apply a porous layer with relatively narrow pores on the outside of the porous sintered metal roller 34.

The intermediate roller 35 and the porous dampening roller 34 have an ink-repellent surface to prevent color is transported back from the pressure plate spanned on the plate cylinder 6a to the porous fountain roller 34 and there clogs the pores through which the fountain solution is to pass. For this purpose, the roller 35 is provided on its surface with a fluoroelastomer or organosilicon layer, which have a low surface energy. As a material, for example, tetrafluoroethylene-hexafluoropropylene-Vinylidenfluoridcopolymer is suitable. Alternatively, the roller 35 also z. For example, be rough chromium-plated or be provided with another hydrophilic metal or ceramic layer, which then, when wetted with water, has ink-repellent properties. The roller 34, however, is provided with an elastic, water-permeable layer. This can z. B. a shrunk plastic membrane of polysulfane or a thin layer of another water-permeable, elastic plastic.

In addition, the roller 35 can be deactivated via an actuator 69 of the dampening roller 37 and the roller 37 can be turned off via an actuator 68 from the plate cylinder 6a. This ensures that after each print interruption or before each resumption of printing the hard, z. B. chrome roller 35 is only once in contact with the porous dampening solution roller or can be brought and so a dampening solution film builds up on its surface before it comes into contact with the possibly contaminated by color dampening roller 37. The actuator 68, with which the dampening roller 37 is employed on the printing plate on the plate cylinder 6a, ensures that the fountain solution is supplied to the printing plate at the times at which the printing plate must be moistened before the start of the printing process. Not shown in detail is the drive for the two rollers 34 and 35, with which the speed of the two rollers can be adjusted independently of the rollers of the inking unit. This makes it possible to generate a slip between the rollers 35 and 37, with the help of which the roller 35 supplied fountain solution in the

Color layer on the dampening roller 37 is effectively emulsified, which forms by the contact with the roller 37 with the inked printing plate.

In the slightly modified embodiment of the invention of Figure 3, the porous dampening roller 34 via two intermediate rollers 35a and 35b with the

Dampening solution roller 37 connected. While the first intermediate roll 35a carries a rubber jacket, which is coated with a material of lower surface energy such. Example, a fluoroelastomer or an organosilicon compound is coated, the second intermediate roller 35b has a ceramic or metal surface, such as a chrome surface. The combination of these two intermediate rolls is very well suited to prevent the return of color from the fountain solution application roller 37 to the porous fountain solution roller 34.

To separate the dampening roller train, the intermediate roller 35a can be lifted off the two rollers 34 and 35b via the actuator 67. Alternatively, the roller 35a may also remain in contact with the porous dampening roller 34 and be separated from the intermediate roller 35b by a pivoting movement about the axis of the roller 34. The shutdown of the dampening unit from the plate cylinder takes place as shown in the figure by a pivoting movement of the roller 37 about the axis of rotation of the roller 36 by means of the actuator 68, while the hard roller 35 can be pivoted with an actuator 69 about the axis of rotation of the roller 35a.

FIG. 4 shows a printing unit 402 for offset printing with a short inking unit. The printing unit has a printing forme cylinder 433, a blanket cylinder 434 and a so-called "anilox" inking unit 403. The anilox

The inking unit 403 comprises an anilox roller 406 and an inking roller 407, both of which are of the same diameter as the printing form cylinder 433. In addition, the anilox Inking unit 403 two adjacent to the anilox roller 408 and 409 and a roller 410, wherein the third roller 410 in turn rests bridged on both rollers 408 and 409. The inking roller 407 has the same diameter as the anilox roller 406 and the printing forme cylinder 433. However, it is provided with a clamping device 411 for mounting a blanket 412, with which the ink transfer from the

Anilox roller 406 is effected on the printing form cylinder 433 or the printing plate mounted thereon. Designated at 415 is a color doctor blade which abuts the anilox roller 406 and receives an ink supply 416.

In this sheet-fed offset printing machine with anilox inking, drawn in the figure dampening unit has a dampening roller 420, a transfer roller 419 and a chrome driver roller 421st

To the transfer roller 419, which carries a color-repellent coating, a porous fountain solution roller 434 is employed. This roller 434 corresponds to the roller 34 according to FIG. 2 and, like the latter, can be turned off the roller 419 via an actuator 467 and, like the latter, is connected to the dampening solution circuit via lines 466a and 466b.

The hard, hydrophilic roller 419 in turn can be turned off by a second actuator 469 by pivoting about the axis of the roller 434 of the roller 420, while the fountain solution supply to the printing plate can be interrupted by an actuator 468, the roller 420 about the axis of the roller 421 pivoted.

The combined ink fountain unit according to the invention shown in Figure 7 consists of a knife ink fountain 713, a fountain roller 714, four inking rollers 728, 729, 730 and 731, with which the printing plate is inked on the cylinder 706a, and a number of other rollers 715 to 727, from which the ink is removed from the ductor 714, distributed and triturated and then fed to the applicator rolls. With 715 the clockwise between the ductor 714 and the roller 721 oscillating color lifter is designated. The rollers 721, 722, 723 and 724 are traversing distributor rollers, the drivers 723 and 724 being cooled. The ductor 715 and the rollers 716, 717, 718, 719, 720 as well as the four inking rollers 728 to 731 are provided with a rubber jacket, while the rollers 727, 726 and 725 are steel rollers.

To the first inking roller 728, a porous fountain solution roller 734 is employed indirectly via an intermediate roller 735. This dampening roller 734 is, as by the

Supply line 766a and the return line 786a indicated connected by means not shown connections to the bearing pin of the roller 734 to a dampening solution circuit. The fountain solution supplied via the line 766a floods the interior of the roller 734 and passes through the porous roll shell at a corresponding overpressure, reaches the intermediate roller 735 and is conveyed by this to the inking roller 728. The structure of the porous fountain solution roller 734 may be as described in the aforementioned WO 2006/047997, d. H. the porous dampening roller 734 may have a two-part construction with a membrane fitting inside the porous roller body 734 having pores of smaller diameter than the pores of the porous roller shell itself. However, it is also possible to have a porous layer with relatively narrow pores on the outside porous sintered metal existing roll 734 apply.

The intermediate roller 735 and the porous dampening roller 734 have an ink repellent surface to prevent ink from being transported back from the inking roller 728 to the dampening roller 734, where it clogs the pores through which the dampening water is to pass. For this purpose, the roller 735 is provided on its surface with a fluoroelastomer or organosilicon layer, which have a low surface energy. As a material for example, tetrafluoroethylene-hexafluoropropylene-Vinylidenfluoridcopolymer is suitable. Alternatively, the roller 735 also z. Example, be chromed rough or be provided with a different hydrophilic metal or ceramic layer, which then, when wetted with water, has color-repellent properties. The roller 734, however, is provided with an elastic, water-permeable layer. This can z. B. a shrunk plastic membrane of polysulfane or a thin layer of another water-permeable, elastic plastic. Furthermore, the fountain solution roller 734 can be shut off via an actuator 767 from the intermediate roller 735. The actuator 767 is connected to the control of the printing machine, which ensures that the fountain solution roller 734 is not turned on the roller when dampening agent emerges from the surface of the roller and wets the surface, so that a sticking of color is avoided.

Another actuator 768 ensures that the roller 735 can be pivoted about the axis of the roller 734 and so can be turned off together with the roller 734 by the inking roller 728. Thus, it is possible to first moisten the roller 735 and make it ink repellent before it comes into contact with the inking roller 728.

Not shown in detail is the drive for the two rollers 734 and 735, with which the speed of the two rollers can be adjusted independently of the rollers of the inking unit. This makes it possible to generate a slip between the rollers 735 and 728, with the help of which the fountain 735 supplied fountain solution in the ink layer on the inking roller 728 is effectively einul giert.

8 shows the modified according to the invention inking another sheetfed offset printing press. Cylinders and rollers with a similar function compared to the embodiment of Figure 7 have a 600 lower

Reference number and are therefore not explained again in each case. Also, this inking unit has four inking rollers 128 to 131, which are used for coloring the printing plate 103 on the plate cylinder 106. 105 is the blanket cylinder of the printing press.

Conventionally, the printing plate 103 is wetted by a film dampening with fountain solution, as shown in the area H with the dotted lines rollers. However, according to the invention, this is eliminated. Instead, a porous dampening roller 134 is indirectly in contact with the surface of the distributor roller 140 of the inking unit via an intermediate roller 135. The roller 140 takes a central

Position in the inking, in so far as it is passed over the entire color flow, the color lifter 115 decreases from the ductor roller 114. Thus, here is central Dampening solution is emulsified into the ink layer transported by the roller 140. This color water emulsion is then distributed over two further rollers 119 and 142 and the rollers 122 and 123 and further rollers 116, 118, 120, 124 and 127 on the four inking rollers. The printing plate 103 assumes at its hydrophilic non-image areas the moisture content of the emulsion, while the image areas are colored with color.

Also in this Ausfϊihrungsbeispiel the dampening roller 134 is offset from the intermediate roller 135 and this in turn can be pivoted about the actuator 168 of the roller 140. Of course, both rollers can be provided with a color-repellent coating here. The coating of the roller 135 is elastic in this case, so z. Example, of a rubber coated with a fluoroelastomer, while the surface of the porous dampening roller 134 is hard and made of sintered metal or ceramic.

Furthermore, it is also possible, the intermediate roller 135 not only in contact with the

Roller 140, but also to run with the roller 141 of the inking unit, when the latter is adapted to the diameter of the roller 140. In this way, an even better emulsifying the dampening solution in the color can be achieved.

The porous fountain solution roller 134 is shown in more detail in FIGS. 10a to c. It consists of a porous carrier sleeve 134a of sintered metal with a thickness of several millimeters. Externally on the carrier sleeve 134a, a porous ceramic layer 134b of, for example, titanium dioxide is applied in a thickness of a few tenths of a millimeter. This layer 134b has become firmly bonded to the carrier sleeve 134a in the course of sintering the titanium dioxide powder from which it originated. The pores in this

Ceramic layer 134b are much smaller than the pores in the support sleeve 134a made of sintered metal. For example, the pore size in the sintered metal is about 1 micrometer and the pore size in the ceramic layer 134b is 0.1 micrometer.

But these are only examples. The pore size can be selected by choosing

Grain of the ceramic or metal powder to be sintered and the process control during sintering vary widely and thus to the needs in individual cases adjust that for a given pressure range for the dampening solution and the dimensions of the roller 134, the desired dampening water volume flow is adjusted.

In addition, it is also possible to produce the outer membrane layer 46 by applying to the carrier sleeve 34a a layer which is subsequently perforated by electron beams, laser beams or by etching.

Insofar as the hydrophilic properties of the ceramic layer 134b or its lipophobic properties are insufficient, the surface of the ceramic layer 134b is additionally vapor-deposited with a lipophobic layer 134c, as shown in FIG. 4b, to a thickness of a few nanometers to ensure that through the additional vapor-deposited layer 134c, the pores in the z. B. porous titanium dioxide layer 134b are not added.

As in the slightly modified embodiment of FIG. 10c, this layer can be dispensed with if the ceramic material of the layer 234b itself is sufficiently hydrophilic or if the surfaces of the grains constituting the ceramic layer 234b are already coated hydrophilic or lipophobic prior to sintering.

An alternative embodiment for the roller 134 of Figure 10a-c is shown in Figures 1 Ia to b. This may be, for example, the fountain solution roller 34 of FIG. This roller has a metal support sleeve 34a, which is several millimeters thick and provided with a plurality of capillary bores 34c. The capillaries have a diameter of several micrometers and can, for. B. mechanically by electron beams, by laser beams or by etching, etc. may have been introduced into the carrier sleeve. Inside the sleeve 34a is a water-permeable plastic membrane 34b z. B. of polysulfan. Alternatively, the membrane layer 34b may also consist of a sintered ceramic or a sintered metal, wherein the pores of the sintered ceramics or the sintered metal with several tenths of a micrometer are small in comparison to the diameter of the bores 34c. The material of the metal sleeve 34a may be, for example, aluminum or steel. The surface of the roller 34 is preferably carried out rough and may additionally be provided, as indicated by the reference numeral 34e, with a chromium layer, which partially also penetrates into the interior of the capillaries 34c.

The membrane layer 34b represents the greatest flow resistance for the dampening water 34d in the interior of the dampening solution roller 34. The dampening water which has passed through here passes into the capillaries 34c and then can only escape radially outward. In particular, it is no longer possible to form a surface flow parallel to the roll surface when individual capillaries have been clogged, for example, by the color transported back. The same applies to the roller 134 in FIG. 4. Here, the outer layer 134b represents the greatest flow resistance. Although adding the pores of this layer may cause an increase in the internal cylinder pressure overall in extreme cases, smeared individual regions lead to the surface of the layer 134b not to the dampening water increasingly in areas adjacent to the areas smeared with paint on the surface of the roller 134b exits when the internal pressure of the fountain solution 34d is kept constant.

FIGS. 12a to c show in more detail the exemplary embodiment of a further porous dampening solution roller. This roller 534 is divided into five individually supplied with fountain solution segments 536, 537, 538 .... These segments are supplied by feed tubes 546, 547 ... from the corresponding feed lines on a rotary feedthrough 541 on the journal 531 of the roller 534.

The individual subsegments 536, 537, 538... Are of similar design as the roller shell 134 in FIGS. 410 a to c, namely of sintered stainless steel support sleeves 536 a, which in this exemplary embodiment are closed off from one another by disk-shaped wall sections 536 c. On the outside of the segment sleeves consisting of the support structure then a thin sintered ceramic layer 536b is applied, which extends over the entire length of the roller 534 (apart from the front-side wall 532 and the pins 530/531). By controlling the pressure of the dampening solution inside the segments 536, 537, 538..., The outlet of the fountain solution from the porous surface of the roller can be controlled zone by zone. It is therefore possible to supply by the use of such a roller of the printing plate locally different amounts of dampening solution. As a result, the print run is more stable in certain subjects or the printer has more room for setting the dampening water balance in the case of spot-shaped subjects.

It may also be advantageous if the fountain solution a gumming agent z. As carboxy-methyl cellulose (CMC) is added. This substance forms on the surface of the dampening solution rollers described in FIGS. 4 to 6 a hydrophilic film which largely prevents clogging of the porous surface with recycled ink.

FIG. 9 shows a printing unit 902 for offset printing with a short inking unit. The printing unit has a printing form cylinder 933, a blanket cylinder 934 and a so-called "anilox" inking unit 903. The anilox inking unit 903 includes an anilox roller 906 and an inking roller 907 both of the same diameter as the printing form cylinder 933. In addition, the anilox inking unit comprises 903 two rollers 908 and 909 resting against the anilox roller and a roller 910, wherein the third roller 910 in turn abuts the two rollers 908 and 909 in a bridge-like manner

Ink roller 907 has the same diameter as the anilox roller 906 and the printing forme cylinder 933. However, it is provided with a clamping device 911 for mounting a blanket 912, with which the ink transfer from the anilox roller 906 takes place on the plate cylinder 933 and the pressure plate mounted thereon. Designated at 915 is a color doctor blade which abuts the anilox roller 906 and receives an ink reservoir 916.

In a known, distributed by the applicant sheetfed offset printing machine with anilox inking the dotted line shown in the figure dampening unit consisting of the water tank, the fountain roller, a transfer roller, the dampening roller and a chrome drive roller. According to the invention, this dampening unit eliminated, creating space for other auxiliary equipment such. B. a washing device.

Instead, a porous fountain solution roller 934 is attached to the remaining bridge roller 922 carrying an ink-repellent coating. This roller 934 corresponds to the rollers 34 and 134 according to FIGS. 2 and 3 and, like these, can be turned off the roller 922 via an actuator 967 and, like the latter, is connected to the dampening solution circuit via lines 966a and 966b. Likewise, the roller 922 may be pivoted about the axis of the roller 934 from the blanket 912 via the actuator 968.

In the schematic diagram of Figure 5 of the dampening solution circuit for supplying the membrane rolls shown in the embodiments for two printing units is shown. Here is located in a reservoir 45, the processed and optionally offset with additives and tempered not shown facilities fountain solution for supplying all the printing units of the printing press. A pump 47 conveys through the line 46, the fountain solution in the inlet 66a and 66b for the two illustrated dampening fountain rollers 34a and 34b, where the dampening water passes through rotary feedthroughs on the bearing pin 44a and 44b in the interior of the rollers 34a and 34b. Between the pump 47 and the supply lines 66a and 66b are each a pressure reducer 48a and 48b and a multi-way valve 49a and 49b.

Via the pressure reducer 48a, 48b, the internal pressure in the membrane roller for each printing unit can be adjusted separately to the value required during the printing operation depending on the printing speed to ensure that the printing plate is sufficiently supplied with fountain solution even at higher printing speeds. This is symbolized by the corresponding arrow. For this purpose, the pressure reducers 48a, 48b are connected to the control of the printing press (not shown here).

The multi-way valves 49a, 49b allow the internal pressure of the membrane rollers to be switched back quickly from the operating pressure (which is the drawn position shown) via the pressure reducers 48a, 48b to a value at which no fountain solution is present emerges from the membrane roller. In this case, when the dampening is to be interrupted (pressure-down), the line 66a is shut off from the inflow and at the same time connected to a surge tank 52, so that the overpressure in the roller 34 can relax quickly in this way. A few tenths of a second thereafter is then indexed to the third position, in which the membrane rolls are also separated from the equalizing vessel 52.

Shown at 51a and 51b are check valves in the return lines 86a and 86b. These valves can be opened at greater intervals to flush the interior of the roll and thus free from deposits under the porous membrane of the rollers 34a, b.

From the reservoir 45, a second circuit is in which a pump 147 and the supply line 166 a much higher volume flow for the purpose of tempering the rollers 34a, b is pumped through them. This circuit is in the interior of the rollers 34a, b separated by a thin, highly thermally conductive sleeve of the actual dampening water flow. In the return 186 of the temperature control circuit is a cooling or heating device 88, which is controlled by a temperature sensor in the storage vessel 45.

In the embodiment of Figure 6 is a comparison with FIG 5 modified

Exemplary embodiment of the dampening solution circuit shown. Here, the interior of the dampening solution rollers 334a and 334b is connected to the dampening solution circuit only from one side via the respective bearing journal and a multichannel rotary union 355a or 355b connected thereto. With the help of separate pumps 357a and b respectively permanently tempered dampening solution is circulated through the interior of dampening solution rollers 334a, b of the respective printing units, wherein cooling elements 353a, b in combination with mixing units 354a, b temper the circulating dampening solution for the rollers 334a, b separately and Keep at the desired temperature for the respective printing unit.

Change-over valves 350a and 350b make it possible to depressurize the rollers 334a and 334b in the respective closed, pre-stressed damping fluid circuits, if necessary. The circuits are supplied via check valves 356a and 356b from a dampening solution reservoir 345, in which case a pump 347 in the supply line 346 in conjunction with a respective pressure reducer 348a and 348b ensure that in the closed temperature control circuits for the respective roller 334a and 334b the desired pressure is maintained.

Rapid lowering of the pressure level in the closed, temperate dampening solution circuit can be achieved by switching valves 349a and 349b. These then separate the pre-stressed combined dampening water supply and

Temperierkreisläufe for the rollers 354a and b of the dampening water supply, while at the same time the switching valves 350a and 350b, the pressure from the interior of the rollers 334a and b in the expansion tank 352 to drain.

Before the printing press shown in FIGS. 2/3 or 4 returns to "print on" after an interruption or the first printing of a new print job, the water pressure in the dampening solution rollers is switched on in all printing units and the respective porous fountain solution roller 34/434 is transferred A few seconds later, when the rollers 35 to 37 of the dampening unit are provided with a fountain solution film, they are then applied to the printing plates via the second actuator 38 and 438, respectively In this way it is ensured that the surface of the rough chrome driver rollers 36 and 421 receive a fountain solution before they take on color due to the contact of the fountain solution application roller 37 and 420 with the printing plate can.

Claims

claims

A rotary flat-plate printing machine with an inking unit with a plurality of inking rollers and a dampening unit with a plurality of dampening rollers, wherein one of the dampening rollers (34; 134; 334; 434; 734; 934) has a porous

Surface has, from which the fountain solution emerges, characterized in that in the dampening solution flow between the dampening roller (34; 134; 334; 434; 734;

934) with the porous surface and the plate cylinder (6a; 433) at least two further rollers (35, 37, 135, 140, 142, 123, 128/129, 419, 420, 735, 728, 922, 907) are arranged.

2. Rotary flat printing machine according to claim 1, wherein the at least two rollers are dampening roller and the surface of at least one (34, 419) of the two intermediate dampening rollers is formed at least in the moistened state ink repellent.

3. A rotary flat printing machine according to claim 1, wherein the fountain solution roller (134; 734; 934) during printing directly or indirectly via one or more rollers (135; 735; 922) to an inking unit roller (140; 728; 907) in the ink flow of the inking unit, preferably an inking roller (28, 407), is employed.

4. rotary flat printing machine according to claim 2, wherein the fountain solution roller (734) via one or more intermediate rollers (735) to the first from the printing nip in the direction of rotation of the plate cylinder (728) of a plurality of inking rollers (728 to 731) is employed.

A rotary flat printing machine according to claim 1, wherein the fountain solution roller (134) is set via one or more intermediate rollers (135) to an inking unit roller (140) in the ink flow of the inking unit.

5. Rotary flat printing machine according to claim 4, wherein the fountain solution roller (134) via at least one intermediate roller (135) to one or more friction rollers (140) of the inking unit is employed.

6. rotary flat printing machine according to one of claims 1 to 5, characterized by

Switching or adjusting elements (48, 49, 348), of which the pressure of the dampening solution in the interior of the dampening solution roller (34, 334, 434) is adjustable.

7. Rotary flat printing machine according to one of claims 1 to 6, characterized by a temperature control device (353, 354), of which the temperature of the dampening solution in the interior of the dampening solution roller (334) is adjustable.

8. rotary flat printing machine according to claim 1, characterized by a storage device (67, 167, 467), via which the contact of the dampening solution roller (34, 434) with other rollers of the dampening unit is interruptible.

9. rotary flat printing machine according to claim 1, characterized by a storage device (68, 168, 468), via which the contact of rollers (34, 134, 434) in dampening solution flow of ink-carrying rollers (28, 140, 407) can be turned off.

10. Rotary flat printing machine according to claim 1, wherein the porous dampening solution roller (34, 134, 334, 434) and / or one or more intermediate rollers, preferably the roller (35, 135, 735, 922) against which the porous dampening roller, at least one possesses in the moistened state ink-repellent surface.

11. Rotary printing machine according to claim 10, wherein the surface is formed as a fluoroelastomer layer or organosilicon layer.

12. rotary flat printing machine according to claim 10, wherein the surface is hydrophilic and consists of metal or ceramic.

13. Rotary flat printing machine according to one of claims 1 to 12, wherein the interior of the porous fountain solution roller consists of individual segments and the pressure in the individual segments is independently adjustable.

14, rotary flat printing machine according to one of claims 1 to 13, wherein the porous roller body of the fountain solution roller has an anisotropic structure such that the flow resistance in the axial direction within the porous roller body is greater than the flow resistance in the radial direction through the roller body.

15 rotary flat printing machine according to one of claims 1 to 11, wherein the roller body is externally provided with a water-permeable membrane and the pores in the membrane are smaller than the pores of the roller body.

16. Rotary flat printing machine according to claim 1, wherein the membrane (134b) at least but the outer surface of the membrane (134b, 536b) is formed ink repellent.

17. Rotary printing machine according to claim 14, wherein the pores of the dimensionally stable carrier (34a) are formed as through holes or channels (34c).

18. Rotary printing machine according to claim 14, wherein the outer surface of the roller body (34 a) with a color-repellent coating (34 e) is provided.

19. Rotary printing machine according to claim 1 to 18, characterized by an engageable with the porous dampening roller cleaning device.

20. Rotary printing machine according to claim 1 to 19, wherein the dampening water (34d, 134d) in the interior of the dampening solution roller (34, 134) contains a gumming agent.