EP0462490B1 - Film dampening system for a rotary press - Google Patents

Description

The present invention relates to printing technology and in particular to dampening devices for sheet-fed and rotary printing machines.

It is well known that the principle of operation of the rotary printing press is based on the fact that bold ink is repelled from a damp surface. For this reason, these printing machines are inevitably equipped with a moistening device, the main task of which is to distribute an even film of dampening solution onto the printing plate stretched around the plate cylinder. This film must be very thin (on the order of a micron) and also very uniform. The slightest non-uniformity would actually lead to a change in the optical density of the printing result (the uniformity of this density changes) and this results in a more or less visible error in the printing result. The aqueous solution used generally contains a certain number of additives, in particular to reduce the surface tension (using isopropyl alcohol) and / or to clean the plate (using citric acid).

There are a number of dampening devices that commonly equip sheetfed and rotary presses.

The humidifiers with a reciprocating lifter should be mentioned first.

The dampening devices of this type consist of a metal plunger roller, which is partly immersed in a fountain solution and which is driven at a slow speed by an independent electric motor, and a pair of rollers which rotates at the speed of the machine (at high speed), namely a chromed one Metal roller, which is the dampening roller, and a rubber-coated dampening roller (which is usually coated with a coating, a kind of textile cover that serves as a reserve) that is in contact with the plate cylinder. Another roller, which is called a siphon roller, is arranged on a reciprocating contact bracket and thus alternately touches the dipping roller and the dampening roller, as a result of which the dampening solution film is transferred from one roller group to the other.

Such moistening devices are used less and less because they do not provide an evenly moist film and make it necessary to use a textile cover, which wears out quickly and has to be replaced regularly, on the dampening roller.

Brush moistening devices should also be mentioned, in which the dampening water is applied to the dampening roller by means of a round brush, the bristle tips of which dip into the dampening water tank and come into contact with firmly attached scrapers, which bend the bristles and produce the spraying of droplets on the dampening roller. In this way, the pair of rollers (namely the chrome-plated dampening roller and the rubber-coated dampening roller) that rotate at the speed of the machine are constantly supplied with dampening water. A variant of this device is that the round brush comes into contact with an immersion roller that is partially immersed in the solution and that the bristles produce a spray of drops.

Such devices, like the dampening water atomizing devices, by the way, are not really satisfactory because the film obtained is never completely regular and the spraying of droplets is rather unsafe.

In order to avoid the aforementioned disadvantages of the moistening devices with reciprocating lifts or with brush moistening devices, film dampening systems are proposed.

Generally, the film moisteners consist of two groups of rollers. A first roller group takes fountain water from the fountain box and rotates at a variable speed, which in any case is much lower than the speed of the machine (the plate arranged on the plate cylinder has a linear speed), this first group of rolls being arranged in such a way that one of the rollers in this group is covered with an even wet film. A second group of rollers touches the plate arranged on the plate cylinder, rotates at the same linear speed as this and enables the fountain solution to be deposited on this plate.

The dampening solution is transferred between these two roller groups via a sliding contact. Indeed, all of the rollers are parallel to each other and touch each other along a surface line (or a transverse contact zone) such that the dampening solution film to be applied evenly to the plate is transported from one roller to another, namely by the dip roller of the first group to the dampening roller of the second group.

• - die beiden Walzen drehen sich im wesentlichen mit der gleichen linearen Geschwindigkeit, aufgrund eines konstanten Verhältnisses und können fest aneinander angestellt werden;
• - die beiden Walzen drehen sich mit sehr unterschiedlichen linearen Geschwindigkeiten und berühren sind schwächer aneinander angestellt, um das relative Gleiten der Walzen zu gestatten.

There are two cases in film humidifiers when two rollers touch along a surface line:

• - The two rollers rotate essentially at the same linear speed, due to a constant ratio and can be placed firmly against each other;
• - The two rollers rotate at very different linear speeds and touch less strongly to allow the relative sliding of the rollers.

In general, the film moisteners available on the market today can be divided into two large groups: the emulsion moisteners with three rollers or the independent moisteners with four rollers.

The film emulsion moistening devices comprise three rollers arranged one after the other: an immersion roller which is coated with elastomer and is partially immersed, a chrome-plated metering roller and an ink or dampening roller coated with elastomer. The moisture film thickness on the metering roller is determined in this device by the passage of the dampening water between the elastomer-coated immersion roller and the chrome-plated metering roller, which are pressed together. A variable speed electric motor drives the plunger roller and the chrome-plated metering roller, which is connected to it via gears, while the dampening roller is in contact with the plate cylinder plate and with the reciprocating dampening roller which is in contact with the speed of the printing press turns. The dampening roller of the emulsion moistening device is thus the only one of the three rollers in said device which is driven at the speed of the machine, the sliding contact taking place directly on the surface of the dampening roller when it comes into contact with the metering roller.

Film emulsion moisteners of the aforementioned type are known, for example, from French Patents No. 1,374,410, No. 1,547,536, No. 2,058,506, No. 2,196,249, No. 2,274,366 and No. 2,448,978.

These film emulsion dampening devices, to which Figure 1 of the accompanying drawings refers below, have the advantage of limiting the channel-related transfers by distributing the excess dampening water which remains on the dampening roller when passing through the channel of the plate due to the sliding contact with the metering roller. However, these humidifiers have the disadvantage that they work with a high proportion of isopropyl alcohol in order to reduce the surface tension (the water-color emulsion actually takes place before contact with the plate).

The independent film moisteners include four rollers arranged in series: a chrome plunge roller (or coated with a water-friendly material) that is partially submerged, an elastomer-coated metering roller, a chrome dampening roller (or coated with a water-friendly material) that moves back and forth, and a dampening roller coated with elastomer. In this moistening device, the wet film thickness is determined by the compression of the chrome dipping roller and the dosing roller coated with elastomer. The electric motor, like the emulsion moistening device, drives the dipping and metering rollers at variable speed, which is connected to it via gearwheels, while the dampening roller is driven at the speed of the printing press. With this moistening device, the sliding contact therefore takes place between the metering roller coated with elastomer and the chrome dampening roller (the strong pressure of the metering roller on the dampening roller is therefore deliberately set to "weak"). The dampening roller of the independent moistening device thus remains in contact with the dampening roller without slipping, and the sliding takes place on the surface of the dampening roller between said dampening roller and the metering roller.

Such independent film humidifiers of the type already mentioned are described, for example, in French Patents No. 1,491,977 and No. 2,211,348.

Such independent film humidifiers, to which Figures 2 and 3 of the accompanying drawings refer below, have the advantage that they use relatively low alcohol concentrations, in particular thanks to the reciprocating motion of the dampening roller, but they have the disadvantage of poor channel-related transmissions eliminate (the excess dampening water that remains on the dampening roller as it passes through the channel of the plate is actually squeezed out on contact between the roller and the dampening roller, but is not leveled, since there is no sliding contact).

Each of the two film humidifiers mentioned above has advantages and disadvantages, and the user must initially choose the humidifier to be used.

This is not so easy, as the printing form to be used and its area coverage as well as the defect to be remedied are not always definitive, so that it seems to be very interesting to be able to use one or the other type of humidification depending on the circumstances .

GB-A-2 082 121 discloses a film dampening unit of the category "independent film dampening devices" for rotary printing presses. The dampening roller is driven at up to twice the peripheral speed compared to that of the dipping roller. This turns on a relative movement of the outer surfaces of the metering roller and dampening roller. The contact pressures of the individual rollers can be varied by means of pneumatic cylinders, as a result of which excess dampening solution can be squeezed out of the nips. However, since - due to the rolling of the channel - an excess of dampening solution remains on the dampening roller, it is difficult to eliminate these channel-related transfers, since there are limits to squeezing out a suddenly occurring linear amount of dampening solution.

Another dampening configuration is from U.S. 4,729,308 became known. There, a dampening medium transfer roller, which is dependent on the plate cylinder drive and a drive which is independent of a separate motor, is realized in that the roller in question can be changed over. As a result, the gearwheel arranged at one end of this roller either engages in a gearwheel connected to a separate electric motor or in a gearwheel of the gear train coming from the plate cylinder. This can be used to change the location at which a relative movement occurs between the surfaces of moving rollers.

However, there are limits to the accessibility of the dampening units - especially in web-fed rotary presses with printing units arranged one above the other - so that printing, inking and dampening units are more accessible on the drive or operator side.

The object of the invention is to propose a combined, convertible film moistening device which optionally comprises two types of moistening, namely emulsion moistening and moistening with four rollers, so that every situation can make the most of the advantages of each device.

One of the objects of the invention is to provide a film moistening device which is easily convertible, i. that is, when switching from one mode of operation to the other, no lengthy and difficult dismantling and adjustment work is required, the changeover points being easily accessible.

Finally, the object of the invention is also to provide a combined and convertible dampening device which can be attached either to a sheet-fed or to a web-fed rotary printing press.

According to the invention, this object is achieved in that a moistening device for a rotary printing press with an immersion roller, which is driven by an electric motor with variable speed, the immersion roller being coated with a water-friendly material and partially immersed in a fountain solution containing dampening solution, with an elastomer coated metering roller, the rotational speed of which depends on that of the dipping roller, with a dampening roller coated with water-friendly material, and with a dampening roller coated with elastomer, which is in contact with the dampening roller and with the plate cylinder of the printing machine, characterized in that it has a releasable coupling agent the dampening roller can optionally be driven by the electric motor, such that differential sliding occurs between the surfaces of the dampening roller and the dampening roller, or the dampening roller can optionally be driven by the plate cylinder such that differential sliding takes place between the surfaces of the dampening roller and the metering roller.

Advantageously, the shaft of the dampening roller carries a small first gear that meshes with the output shaft of the electric motor and a second small gear that meshes with the shaft of the plate cylinder, the releasable clutch rotating said shaft of the dampening roller with the first or the second small gear connects, the other small gear being movably provided on said shaft. The releasable clutch or coupling means comprises in particular a disk which is arranged at each end of the shaft of the dampening roller, each disk adjoining the first or the second gearwheel, the coupling between the respective disk and the respective gearwheel being effected by means of connecting bolts.

Preferably the releasable clutch comprises a locking means which prevents the simultaneous coupling of the dampening roller with the electric motor and the plate cylinder; the connecting bolts mentioned above are provided in a sufficient number for coupling a single disk to the gear in question in order to rule out a possible simultaneous coupling of the two disks.

According to an interesting variant, the moistening device comprises another variable speed electric motor which drives the dampening roller directly, this electric motor running either at the speed of the metering roller or at that of the plate cylinder. In particular, a tachometer generator, which is mounted on the shaft of the plate cylinder, and a speed sensor, which is connected to each of the electric motors, are provided, the drive motor of the dampening roller being equipped with an electronic control device, which is either from the speed sensor of the drive motor of the plunger roller or signals coming to the tachogenerator of the plate cylinder.

According to another variant, the metering roller is also partially immersed in a dampening water tank and mechanical means are provided for displacing the shaft of the immersion roller, the differential sliding either between the dampening and dampening application roller when the immersion is stopped by the metering roller, or between the dampening roller and the dosing roller are generated when the dipping roller comes into contact with the dosing roller.

The mechanical means which make it possible to move the shaft of the plunger roller therefore essentially consist essentially of the contact brackets which are rotatably mounted on the frame of the printing press and are arranged on both sides of the plunger roller, each contact bracket having a positioning means. In particular, the contact brackets rotate about an axis which runs coaxially to the shaft of the metering roller, the positioning means being designed in the form of a toggle screw which extends through two bearings which are arranged on the respective shaft of the immersion or metering roller.

Advantageously, the moistening device also includes an independent reciprocating mechanism, namely a worm gear connected to the dampening roller, such that the dampening roller is moved with a predetermined alternating reciprocating motion in one or the other type of moistening.

According to another advantageous feature, the dampening device is supplemented by a bridge roller, which is arranged between the dampening roller and the closest inking roller, the bridge roller making contact between the dampening and inking rollers in one or the other type of dampening and also on the drive of the Dampening roller. In particular, the bridge roller is either arranged to be movable or is driven at the speed of the plate cylinder.

The bridge roller is advantageously arranged on the frame of the printing press with an eccentric device which makes it possible to establish or interrupt the contact between the bridge roller and the dampening roller.

• Fig. 1 ist eine schematische Schnittansicht einer bekannten Emulsionsbefeuchtungseinrichtung mit drei Walzen,
• Fig. 2 ist eine schematische Schnittansicht einer unabhängigen Filmbefeuchtungseinrichtung mit vier Walzen,
• Fig. 3 zeigt einen vergrößerten Ausschnitt der das Problem des kanalbedingten Übertrags veranschaulicht, mit der Erhöhung, die von dem überschüssigen Feuchtwasser auf der Farb- bzw. Feuchtauftragwalze beim Passieren des Kanals der Platte gebildet wird.
• Fig. 4 ist eine schematische Schnittansicht einer erfindungsgemäßen umstellbaren Befeuchtungseinrichtung,
• Fig. 5 zeigt zum Teil eine Schnittansicht von Fig. 4, die gemäß Ebenen, die durch die Achsen der Walzen (Linie AA, BB, CC, DD der Fig. 4) gehen, entwickelt wurde; diese Schnittansicht läßt den Antriebselektromotor der Tauchwalze sowie die lösbare Kupplung (hier mit einer Scheiben-Zahnradanordnung, die man an jedem Ende der Welle der Feuchtreibwalze durch Verschraubung befestigen kann) sowie den sich hin-und herbewegenden Mechanismus der Feuchtreibwalze erkennen,
• Fig. 6 ist eine Fig. 5 entsprechende Schnittansicht, die eine Variante aufweist, bei der die Feuchtreibwalze separat von einem zweiten Elektromotor angetrieben wird, der entweder mit der Geschwindigkeit der Tauchwalze oder mit der des Plattenzylinders umläuft,
• Fig. 7 ist eine Fig. 4 entsprechende schematische Schnittansicht, die eine andere Variante der Erfindung aufweist, bei der auch die Dosierwalze zum Teil eingetaucht ist; die Tauchwalze kann von der Dosierwalze an- bzw. abgestellt werden, je nach dem welche Filmbefeuchtungsart man wählt.

Other features and advantages of the invention will appear more clearly in the following description and in the accompanying drawings, which relate to a specific embodiment with reference to the following figures:

• Fig. 1 is a schematic sectional view of a known three-roller emulsion humidifier,
• Fig. 2 is a schematic sectional view of an independent film roller with four rollers,
• Fig. 3 shows an enlarged section illustrating the problem of channel-related transfer, with the increase that is formed by the excess fountain solution on the ink or dampening roller when passing through the channel of the plate.
• 4 is a schematic sectional view of a convertible humidifying device according to the invention,
• Fig. 5 shows in part a sectional view of Fig. 4 developed according to planes passing through the axes of the rolls (line AA, BB, CC, DD of Fig. 4); this sectional view reveals the drive electric motor of the dipping roller and the releasable coupling (here with a disk gear arrangement which can be fastened to each end of the shaft of the dampening roller by screwing) and the reciprocating mechanism of the dampening roller,
• 6 is a sectional view corresponding to FIG. 5, which has a variant in which the dampening roller is driven separately by a second electric motor which rotates either at the speed of the dipping roller or at that of the plate cylinder,
• FIG. 7 is a schematic sectional view corresponding to FIG. 4, which has another variant of the invention, in which the metering roller is also partially immersed; the dipping roller can be turned on or off by the metering roller, depending on the type of film moistening selected.

1 shows an emulsion moistening device 1 with three rollers.

As mentioned above, the film moistening device 1 successively comprises an immersion roller 2 coated with elastomer, a chrome-plated metering roller 3 and an inking or dampening application roller 4 coated with elastomer contains; In addition, a constant water inflow (faucet 9) and an overflow (pipe 10) are provided, which keep the fountain water level in the water tank or in the fountain tank 7 constant. One of the rollers 2 and 3 (here it is the dipping roller 2) is driven by an electric motor 11 with variable speed by means of a belt 12 (or moreover by means of a cardan device not shown here) driven. The dipping roller 2 is in contact with the chrome-plated metering roller 3, these two rollers being connected to one another by intermeshing gearwheels 13, 14 (shown here in phantom). Since the gears of the dipping roller 2 and the metering roller 3 mesh with one another, the speed of these two rollers is proportional (generally in a ratio of 1: 3).

The dampening roller 4 is in contact with the plate cylinder 5, on which the printing plate 6 is clamped. The inking roller 4 is also in contact with a reciprocating inking roller 15 which is driven at the speed of the machine, and this inking roller is in turn in contact with an inking roller 17 and an adjacent inking roller 16 (the first one) Group of three or four inking rollers), these latter rollers belonging to the inking unit of the offset rotary printing machine. The ink or dampening roller 4 is thus driven at the speed of the printing press and the chrome-plated metering roller 3 is in turn driven by the electric motor 11; the ink or dampening roller 4 very lightly touches the chrome-plated metering roller 3, on which it slides and from which it removes a fine dampening film. In such a film moistening device, the passage of the fountain solution between the immersion roller 2 and the chrome roller 3, which are pressed against one another, determines the fountain solution film thickness present on the metering roller. In the specific case, the differential sliding zone 20 corresponds to the contact zone between the metering roller 3 and the inking or dampening roller 4 (the contact between the immersion roller 2 and the metering roller 3 is in turn either slip-free or with sliding in a fixed ratio, but without differential sliding takes place).

As mentioned above, this type of humidification has the advantage of limiting channel-related transmission. In fact, the plate cylinder 5 is provided with a channel 18, which enables the plate 6 to be clamped in such a way that excess dampening water remains on the inking or dampening roller 4 as it passes through the channel 18, but this error is made with the sliding contact 20 leveled between the metering roller 3 and the inking or dampening roller 4 due to the differential sliding between the rollers. As mentioned above, this type of humidification requires large amounts of isopropyl alcohol to function properly. This is due to the fact that the water-color emulsion takes place before contact with the printing plate 6.

Fig. 2 shows another known film moistening device, which is hereinafter referred to as an independent moistening device with four rollers.

Such a moistening device 50 comprises, in succession, an immersion roller 51 which is chrome-plated (or coated with a water-friendly material) and is partially immersed in a dampening water tank 57 containing the dampening water 58, a metering roller 52 coated with elastomer and a chrome-plated reciprocating dampening roller 53 (or coated with a water-friendly material) and an ink or dampening roller 54 coated with elastomer. As mentioned above, the drive is carried out by an electric motor 61 with variable speed and by a belt 62; a device with a tap 59 and an overflow pipe 60 ensures an adequate dampening solution level. The dipping roller 51 and the metering roller 52 work together via meshing gears 63, 64, as was the case with the first pair of rollers in the emulsion moistening device already mentioned.

However, the film thickness is determined by the compression between the chrome plunge roller 51 and the dosing roller 52 coated with elastomer. The inking or dampening roller 54 is - as in a previous example - in contact with the plate cylinder 55 which carries the printing plate 56 and whose channel 68 can be seen. In such a moistening device, the dampening roller 53 is driven and moved back and forth; it is easily placed against the adjacent metering roller 52: the sliding contact (namely the differential sliding) takes place between the metering 52 and the dampening roller 53 in a zone 70. The dampening roller 54, which applies the dampening film to the pressure plate 56, lies between elements, that rotate at the speed of the press, d. that is, on the one hand between the plate 56 and on the other hand between the chrome-plated dampening roller 53, in such a way that the excess water caused by the channel 68 of the plate is not eliminated or is not even partially leveled (in contrast to the emulsion moistening device already mentioned, the contact between the Moist friction 53 and the dampening roller 54 slip-free or with a sliding in a fixed ratio and therefore shows no differential sliding).

Fig. 3 clearly shows the defect caused by the channel 68 of the plate: in fact in this figure on the surface of the dampening roller 54 one can see a part of the film 69 which has a single elevation 71 which corresponds to the transfer of the channel 68 Pressure plate 56 corresponds. This increase 71, which corresponds to an excess of water, which remains on the surface of the dampening roller 54 and is compressed only on further contact with the dampening roller 53 without being leveled due to the lack of differential sliding on this contact.

2 and 3 also have a bridge roller 65 which is arranged between the dampening roller 54 and the first inking roller 66. This bridge roller 65 improves the operation of the moistening device 50; with certain printing forms, this moistening device works better than the emulsion moistening device 1. The bridge roller actually enables printing with alcohol substitutes instead of high-proof alcohol. Furthermore, due to the reciprocating movement of the moistening device, the errors on the printed product that are caused by local strips or Scratches on the dampening roller or the chrome roller.

As is apparent from the foregoing description relating to the known dampening devices, it is important to note that in the emulsion dampening device 1 in Fig. 1, only the inking or dampening roller 4 rotates at the speed of the printing machine, and that the sliding with the other rollers on their surface (differential sliding with the sliding contact 20), while with the independent moistening device 50, which is shown in FIGS. 2 and 3 with four rollers, the inking or dampening roller 54 is slip-free (or with sliding) remains in contact with the dampening roller 53, these two elements being driven at the speed of the machine, and sliding with the other dampening rollers on the surface of the dampening roller 53 (for the sliding contact 70 this corresponds to the differential sliding zone between the Dosing 52 and the dampening roller 53). In the four-roller dampening device 50, the dampening unit also includes a reciprocating dampening roller 53, thereby reducing the dampening irregularities in the direction of the roll width.

A combined and convertible film moistening device according to the invention is described below, which optionally has two different operating modes, namely emulsion moistening and independent moistening with four rollers, so that the advantages of each type of moistening can be optimally used for each special situation.

In Fig. 4 can be seen a film moistening device 100, which successively comprises a dip roller 101 partially immersed in a fountain solution 107, which contains the fountain solution 108, the dip roller being driven by an electric motor with variable speed (not shown) and with a water-friendly material (e.g. a chrome-plated outer surface), as well as a metering roller 102 coated with elastomer, the rotation speed of which corresponds to that of the dip roller 101, and a dampening roller 103 coated with a water-friendly material (e.g. chrome-plated on the outside) and one coated with elastomer Damping roller 104, which is in contact with the dampening roller 103 and with the plate cylinder 105 of the printing press. The dipping roller 101 and the metering roller 102 are connected to one another via intermeshing gear wheels 113, 114 in such a way that their speeds are proportional to one another. The dampening water tank 107 also includes a constant water supply (tap 109) and an overflow (pipe 110), which correspond to the elements described above.

Until then, the film moistening device 100 according to the invention behaves like a moistening device with four rollers, which is related to the known independent moistening devices which have already been mentioned in connection with FIGS. 2 and 3. Nevertheless, there is an essential difference between the dampening device 100 according to the invention and the independent dampening device 50 with four rollers, this difference being the way the dampening roller is driven.

In fact, according to a main feature of the invention, the dampening roller 103 of the moistening device 100 can either be driven by the metering roller 102 in such a way that differential sliding between the rollers, namely between the dampening roller 103 and the dampening roller 104 (through the sliding contact 120) takes place , or from the plate cylinder 105, such that a differential sliding between the rollers, namely between the dampening roller 103 and the metering roller 102 (by a sliding contact 119) is produced, the selective drive of the dampening roller 103 in the same way one or the other of the used two different types of humidification.

When a selective drive is provided for the dampening roller 103 either via the metering roller 102 or via the plate cylinder 105, a combined and convertible film moistening device can be realized, which optionally has two different types of moistening, namely emulsion moistening or independent moistening with four rollers.

A first exemplary embodiment of this selective coupling of the dampening roller 103, which is described below, is illustrated in FIG. 5.

The section through FIG. 5 shows the dipping roller 101, which is partially immersed in the fountain solution 107, the roller being equipped with an electromo gate 111 is driven at variable speed. For this purpose, the output shaft 126 of the electric motor 111 comprises a small gear 125, which meshes with another small gear 127, which is attached coaxially to the dip roller 101, but is coupled to the shaft 123 of the dip roller by means of a cardan drive 124. The metering roller 102 in turn rotates around its shaft 128 which is attached to the frames of the printing press (frame 121 is often called the drive side and frame 122 the operator side). The gears 113 and 114 connect the plunger roller 101 to the metering roller 102. The chrome-plated dampening roller 103 is rotatably supported on the frames 121 and 122 by its shaft 141, a reciprocating device 155 being provided at one end of this shaft is described in more detail. The dampening roller 104 is in turn arranged by its shaft 147 on two contact brackets 148 and 149 which are rotatably mounted on the frames 121 and 122, respectively. The plate cylinder 105, which carries the pressure plate 106, is in turn rotatably supported by its shaft 151 on the frames 121 and 122. The moistening device 100 in this case comprises a releasable coupling or coupling means 150, via which the dampening roller 103 either with the electric motor 111, the drives the dip 101 and the metering roller 102, or is connected to the plate cylinder 105.

In this specific case, the shaft 141 of the dampening roller 103 carries a first small gear 144 which meshes with the output shaft of the electric motor 111 (or more precisely, with the small gear 125 which is mounted on the output shaft 126 of the motor) and a second small gear 145, which meshes with the shaft 151 of the plate cylinder 105 (more precisely, with a gear 152, which is fixedly connected to the shaft 151 of the plate cylinder 105, by means of a small intermediate gear 153 which is movably arranged on a pin 154, which is on operating side 122). The releasable clutch 150 enables the shaft 141 of the dampening roller 103 to either rotate together with the first gear 144, such that the second gear 145 is movably supported on the shaft 141, or with the second gear 145, such that the first gear is arranged to be just as movable on the shaft 141.

There are, of course, several ways of realizing such a releasable clutch by using known toothed or friction clutches with an electrical, mechanical, pneumatic or hydraulic drive. A special embodiment of this releasable coupling is presented here, which is particularly simple, and which also comprises a locking means which prevents the simultaneous coupling of the dampening roller 103 with the electric motor 111 and with the plate cylinder 105.

The releasable clutch 150 comprises a disk 142 or 143 which is mounted at each end of the shaft 141 of the dampening roller 103; each disc 142 or 143 adjoins the first gear 144 or the second gear 145, and the coupling between the disc and the gear 142, 144 or 143, 145 in question takes place by means of stud bolts 146. It is found that here each Gear 144 and 145 is provided with a recess which receives the adjacent disk 142 and 143, the holes have an internal thread, which firmly connect the disk to the gear by means of bolt screws 146. It goes without saying that when moving from one type of dampening to the other, the printing machine is stopped, the stud bolts 146 are removed from the unit formed by the gear and the disk and on the other side of the printing machine in the gear-disk unit must be screwed on again.

When the releasable clutch 150 rotates the disk 142 with the first gear 144 (left side Fig. 5), the dampening roller 103 is driven directly by the metering roller 102, such that the differential sliding between rollers, namely between the dampening roller 103 and the dampening roller 104, which creates contact zone 120. This type of moistening consequently corresponds to the previously mentioned emulsion device, with the exception that it consists of four and not three rollers. However, when the stud bolts 146 are used to connect the washer 143 to the second gear 145 (right side FIG. 5), the gears 152 and 153 allow the shaft 141 of the dampening roller 103 to be connected to the shaft 151 of the plate cylinder 105 , such that the dampening roller 103 is driven directly by the plate cylinder 105, and the differential sliding between the rollers, namely between the dampening roller 103 and the metering roller 102, is generated according to a type of dampening of the independent four-roller device described above.

In addition, the releasable clutch 150, as described above, includes a locking means which enables the simultaneous coupling of the dampening roller 103 with the electric motor 111 and the plate cylinder 105 due to a just sufficient number of connecting bolts 146 which are used for the coupling of a single disc 142 and 143, respectively the gear 144 or 145 in question are prevented. In this way, any risk of a simultaneous coupling of the two disks 142, 143 can be excluded in a simple and reliable manner.

Thus, according to a very important feature of the invention, the film moistening device 100 comprises a dampening roller 103 (here a chrome-plated roller), which can be driven either at the speed of the printing machine or at the linear speed of the metering 102 and the immersion roller 101, as desired by the user, which is supplied by an independent electric motor 111.

4, it can also be seen that a bridge roller 115 is arranged between the dampening roller 104 and the closest inking roller 116. In both the one of the previously mentioned types of moistening, the bridge roller 115 makes contact between the dampening roller 104 and the first inking roller 116 and also participates in the drive of the dampening roller 104. Such a bridge roller is therefore advantageous in that it not only secures a bridge between water and ink in the traditional way, but also supports the drive of the dampening roller 104, thereby preventing excessive pressure between the dampening roller and the plate cylinder (because excessive pressure could actually squeeze the film). The dip roller 101, which rotates in the direction of the arrow, transfers a dampening solution film to the line of contact between the dip roller 101 and the metering roller 102; the metering roller distributes and limits the thickness of this liquid film by passing only a metered film between the two rollers, which is much finer and more regular. In an emulsion moistening device, the bridge roller 115 proves to be particularly advantageous because it ensures good driving of the dampening roller 104. In fact, the bridge roller 115 is in contact with the inking roller 116 and supports the drive, in particular when passing through the channel 118, in the pressure line between the dampening roller 104 and the pressure plate 106.

As already mentioned above, a reciprocating mechanism 155 is also provided which is connected to the dampening roller 103; an exemplary embodiment is described in FIG. 5. One can actually see a reciprocating mechanism 155, which essentially comprises a worm wheel 156 and a worm 157, the worm of which is fixedly connected to the shaft 141 of the dampening roller 103 and the worm wheel of which is provided with an eccentric device 160, which connects with the frame 122 via a connecting rod 159, which is movably mounted on the frame 122 at the pivot point 161. Such a worm gear is mounted on the movable housing 158 in such a way that the rotary movement of the dampening roller 103 alternately produces a forward and backward translation movement. Such a device can also be implemented by other appropriate means, which are usually known to those skilled in the art under the name of a reciprocating device. The purpose of this device is to give the dampening roller 103 an alternating back and forth movement of a small size (of approximately 8 mm) and with a frequency of 5 to 6 dampening roller revolutions in order to make a forward and backward translation movement possible. In practice, this frequency is determined by the worm gear. It should be noted here that the reciprocating mechanism 155 connected to the dampening roller 103 is designed so that it can be used in the two types of humidification, since the adjacent releasable coupling 150 can engage independently of the reciprocating mechanism .

5 shows the mechanical means 131 and 132 for setting the pressure force used between the metering roller 102 and the plunger roller 101. The adjustment means 131 thus comprises a contact bracket 129 which is rotatably mounted on the frame 121 of the printing press, said contact bracket being able to rotate about the axis 162 which runs coaxially with the shaft 128 of the metering roller 102. Two bearings 137, 138 are connected to the shaft 123 of the plunger roller 101 and the shaft 128 of the metering roller 102, respectively, and a screw spindle 133 with an operating lever 135 passes through these two bearings in such a way that that from the rotation of the said lever into the respective one Direction generated coupling and uncoupling of the bearings 137, 138 changes the contact pressure force between the two rollers in question. At the other end of this pair of rollers there is of course a symmetrical device, a mechanical means 132, which also comprises a contact bracket 130 which is rotatably mounted on the frame 122 of the printing press about the axis 163, which is coaxial with the shaft 128 of the metering roller 102 and a screw spindle 134 with an operating lever 136, which enables the engagement and disengagement of the bearings 139, 140, which are connected to the shaft 123 of the plunger roller 101 and to the shaft 128 of the metering roller 102.

The aforementioned bridge roller 115 cannot be seen in the sectional view of FIG. 5; however, the use of such a roller is in the independent four roller humidifiers such. B. the humidifier 50 described with reference to FIGS. 2 and 3, already known. This bridge roller 115 can be movably mounted or additionally driven at the speed of the plate cylinder 105 will. In addition, it is advantageous to arrange the bridge roller 115 on the frame of the printing press with an eccentric device which makes or breaks the contact between the bridge 115 and the dampening roller 104.

As already explained, the movement of the dampening roller 103 can either be from the electric motor 111 via the gear wheels 125, 144, the bolt screws 146 and via the washer 142 or from the plate cylinder 105 via the gear wheel 152 and the gear wheels 145, 153, the same bolt screws 146 and generated over the washer 143 (provided that the latter washer is connected to the gear 145 through the bolt screws 146). Depending on the circumstances, the dampening roller 103 rotates either at a linear speed generated by the motor 111 or at the linear speed generated by the printing press.

Two variants of the moistening device according to the invention are described below with reference to FIGS. 6 and 7, these variants comprising different means for realizing the selective drive for the dampening roller 103 either over the metering roller or over the plate cylinder, always from the point of view of one Perform film humidification device that can be combined and converted at the same time.

6 shows a first variant 200 of the dampening device according to the invention, in which the dampening roller 103, now continuously with a second electric motor 171, is also driven at a variable speed, instead of the dampening roller 103 — with one or the other gearwheel — according to the wishes of the user connect to.

The film humidifier 200 comprises a large number of elements which the aforementioned film humidifier 100 has, and consequently need no further description.

In the film moistening device 200, the shaft 141 of the dampening roller 103 always includes a reciprocating mechanism 155, but no longer a releasable coupling 150, which was provided on both sides of the press frame. It is still possible to use the washer 142 and the first gear 144 which is connected to it by bolts 146, using these elements from the previous device (of course, this functional unit could be replaced by a single gear which is associated with the shaft of the dampening roller rotates).

On the output shaft 172 of the electric motor 171, a gear 173 is provided, which in this case meshes with the gear 144 of the dampening roller 103 such that it can drive the dampening roller 103 continuously. The electric motor 171 of the film moistening device 200 also runs either at the speed of the metering roller 102 or at that of the plate cylinder 105, as a result of which the dampening roller 103 can be driven either via the metering roller 102 or via the plate cylinder 105; this also applies to the film moistening device described above. This selective drive of the dampening roller thus enables the use of one or the other type of moistening. Of course, the aforementioned speeds of metering roller 102 and plate cylinder 105 are linear speeds on the surface of these rollers.

The electric motor 171 preferably runs at the speed of the speed controller 176. The control circuit of the electric motor 171 can be oriented in such a way that a speed sensor 177 is connected to the electric motor 111, which drives the immersion 101 and the metering roller 102, another speed sensor 174 with is connected to the electric motor 171, which drives the dampening roller 103, and a tachometer generator 180 is connected to the plate cylinder 105. The speed controller 176 thus receives signals coming from the speed sensors 177, 174 via electrical connections 178 and 175, as well as signals coming from the tachometer generator 180 via an electrical connection 181. In addition, a switchover device 179 is provided at the input of the speed controller 176. When the switching element 179 is in the position which is indicated by a solid line, the speed controller 176 receives the signals from the speed sensor 174 and the tachometer generator 180, the speed of the motor 171 being adapted to the speed of the plate cylinder 105 (this is what is involved here) it is the independent type of humidification with four rollers); and when the switch 179 is in the dotted position, the speed controller 176 receives the signals from the speed sensors 174 and 177, the speed of the motor 171 being adapted to the speed of the metering roller 102 (this is the type of emulsion moistening).

In emulsion humidification, the voltage setpoint that determines the speed of motor 171 is provided by speed sensor 177, which is driven by motor 111 in such a way that motor 171 rotates at the speed proportional to motor 111. In contrast, in the case of the independent type of humidification with four rollers, the voltage setpoint that is supplied to the switching element is determined by the one with tachometer generator 180 connected to the printing press (in this case to the plate cylinder 105), consequently the motor 171 runs at a speed which corresponds to or is proportional to that of the printing press.

This variant is interesting in that it enables a simple transition from one type of humidification to the other, by acting only on the switching element. However, it requires a second electric motor with variable speed.

7 shows another exemplary embodiment of a moistening device 300 according to the invention, in which the metering roller 102 - like the immersion roller 101 - is partially immersed in the wet box 107. The moistening device 300 thus formed comprises mechanical means for displacing the shaft of the immersion roller 101 such that the differential sliding either between the dampening roller 103 and the dampening application roller 104 when the immersion roller is stopped by the metering roller 102, or between the dampening roller 103 and of the metering roller 102 is generated when the dipping roller comes into contact with the metering roller. In this other variant, attempts have been made to make use of the possibility of pivoting the immersion roller 101 transversely relative to the adjacent metering roller 102, which is also partially immersed (such a shift is indicated in FIG. 7 by the arrow 190).

The mechanical means provided for displacing the shaft of the plunger roller 101 can be of various types; above all, the mechanical means 131 and 132 already described with reference to FIG. 5 can be used. However, in this case the mechanical means 131 and 132 not only have the task of regulating the contact pressure of the roller pair in question, but also of moving the plunger roller 101 between two working positions, namely from a first "parked" position, in which the Dip roller is parked by the metering roller, and in an "adjusted" position, in which the dip roller 101 is pressed strongly against the metering roller 102.

When the plunger roller 101 is stopped by the metering roller 102 by means of position adjustment members 133, 135 and 134, 136, the metering roller 102, which rotates in the direction of the arrow, transfers a thick film which, by passing between the dampening 103 and the metering roller 102, is dosed. In this mode of operation, which corresponds to the first working position of the plunger roller 101, the metering roller 102 and the dampening roller 103 rotate at approximately the same speed, while the dampening roller 104 continues to be driven at the speed of the printing press. The differential sliding takes place in the zone 120 between the dampening roller 104 and the dampening roller 103, and the distribution of the film takes place through these rollers, the contact force of which naturally decreases, so that the differential sliding can take place. This is a type of emulsion moistening.

However, when the operator acts on the position adjustment members 133, 135, 134, 136 such that the plunger roller 101 is strongly pressed against the metering roller, the dampening film thickness is determined by its passage between the dipping roller 101 and the dosing roller 102, which are approximately the same Rotate speed, which speed is supplied by the drive electric motor 111. The film expands as it is transferred to the dampening roller 103 which rotates at the speed of the printing press; and as it passes between the dampening 103 and dampening rollers 104, there is a simple transfer between rollers rotating at approximately the same speed. Differential sliding takes place in zone 119 between metering roller 102 and dampening roller 103. This is an independent type of humidification with four rollers.

In particular, it is conceivable to replace the clutch mechanism of the dampening roller 103 either with a completely different type of positive or frictional clutch type or the like. Likewise, the floating independent worm gear could be replaced by another equivalent model, e.g. B. can be replaced by a fast electromagnetic or a positive coupling.

Of course, the bridge roller 115 can be dispensed with in the film moistening device according to the invention in that - in one variant - the dampening roller 104 can be driven mechanically via a gearwheel which is connected to the printing press (e.g. the plate cylinder) in such a way that for the Drive function does not require a bridge roller (such an arrangement could even cause vibrations that would affect the uniformity of the pressure). The advantages of the bridge roller 115 are retained, regardless of whether it is made of metal with a surface that is easily wettable with paint (plastic or copper) or with an elastomer. In general, this bridge roller is preferably provided with an eccentric device which establishes or interrupts the contact between itself and the dampening roller.

Other ancillary facilities such as B. the eccentric mechanism of the dampening roller, the metering roller or the bridge roller, and the one Setting devices of the rollers have not been described in this context. These traditional devices are used in all humidifiers currently in use.

REFERENCE SIGN LIST

• 1 Befeuchtungseinrichtung
• 2 Tauchwalze
• 3 Dosierwalze
• 4 Farb-/Feuchtauftragwalze
• 5 Plattenzylinder
• 6 Druckplatte
• 7 Feuchtwasserkasten
• 8 Feuchtwasser
• 9 Wasserhahn
• 10 überlauf
• 11 Elektromotor
• 12 Riemen
• 13 Zahnrad
• 14 Zahnrad
• 15 Farbreibwalze
• 16 Farbauftragwalze
• 17 Farbverteilerwalze
• 18 Kanal
• 20 Differentialgleitzone
• 50 Befeuchtungseinrichtung
• 51 Tauchwalze
• 52 Dosierwalze
• 53 Feuchtreibwalze
• 54 Farb-/Feuchtauftragwalze
• 55 Plattenzlinder
• 56 Druckplatte
• 57 Feuchtwasserkasten
• 58 Feuchtwasser
• 59 Wasserhahn
• 60 überlauf
• 61 Elektromotor
• 62 Riemen
• 63 Zahnrad
• 64 Zahnrad
• 65 Brückenwalze
• 66 Farbauftragwalze
• 68 Kanal
• 69 Film
• 70 Gleitkontakt
• 71 Erhöhung
• 100 Befeuchtungseinrichtung
• 101 Tauchwalze
• 102 Dosierwalze
• 103 Feuchtreibwalze
• 104 Feuchtauftragwalze
• 105 Plattenzylinder
• 106 Druckplatte
• 107 Feuchtwasserkasten
• 108 Feuchtwasser
• 109 Wasserhahn
• 110 überlauf
• 111 Elektromotor
• 113 Zahnrad
• 114 Zahnrad
• 115 Brückenwalze
• 116 Farbauftragwalze
• 118 Kanal
• 119 Gleitkontakt
• 120 Gleitkontakt
• 121 Gestell (Antriebsseite)
• 122 Gestell (Bedienungsseite)
• 123 Welle
• 124 Kardanantrieb
• 125 Zahnrad
• 127 Zahnrad
• 126 Abtriebswelle
• 128 Welle
• 129 Kontaktbügel
• 130 Kontaktbügel
• 131 mechanische Mittel
• 132 mechanische Mittel
• 133 Schraubenspindel
• 134 Schraubenspindel
• 135 Bedienungshebel
• 136 Bedienungshebel
• 137 Lager
• 138 Lager
• 139 Lager
• 140 Lager
• 141 Welle
• 142 Scheibe
• 143 Scheibe
• 144 Zahnrad
• 145 Zahnrad
• 146 Bolzenschrauben
• 147 Welle
• 148 Kontaktbügel
• 149 Kontaktbügel
• 150 Kupplung
• 151 Welle
• 152 Zahnrad
• 153 Zahnrad
• 154 Zapfen
• 155 hin- und herbewegender Mechanismus
• 156 Schneckenrad
• 157 Schnecke
• 158 Gehäuse
• 159 Pleuelstange
• 160 exzentrische Einrichtung
• 162 Achse
• 163 Achse
• 171 Elektromotor
• 172 Abtriebswelle
• 173 Zahnrad
• 174 Drehzahlgeber
• 175 elektrische Verbindung
• 176 Geschwindigkeitsregler
• 177 Drehzahlgeber
• 178 elektrische Verbindung
• 179 Umschaltorgan
• 180 Tachogenerator
• 181 elektrische Verbindung
• 190 Pfeil
• 200 Befeuchtungseinrichtung

300 Befeuchtungseinrichtung

• 1 humidifier
• 2 dipping roller
• 3 metering roller
• 4 ink / dampening roller
• 5 plate cylinders
• 6 pressure plate
• 7 fountain solution box
• 8 fountain solution
• 9 faucet
• 10 overflow
• 11 electric motor
• 12 straps
• 13 gear
• 14 gear
• 15 inking roller
• 16 inking roller
• 17 ink distribution roller
• 18 channel
• 20 differential sliding zone
• 50 humidifier
• 51 dipping roller
• 52 metering roller
• 53 dampening roller
• 54 ink / dampening roller
• 55 plate cylinders
• 56 pressure plate
• 57 fountain solution box
• 58 fountain solution
• 59 water tap
• 60 overflow
• 61 electric motor
• 62 straps
• 63 gear
• 64 gear
• 65 bridge roller
• 66 inking roller
• 68 channel
• 69 film
• 70 sliding contact
• 71 increase
• 100 humidifier
• 101 dipping roller
• 102 metering roller
• 103 dampening roller
• 104 dampening roller
• 105 plate cylinders
• 106 printing plate
• 107 fountain solution box
• 108 fountain solution
• 109 faucet
• 110 overflow
• 111 electric motor
• 113 gear
• 114 gear
• 115 bridge roller
• 116 inking roller
• 118 channel
• 119 sliding contact
• 120 sliding contact
• 121 frame (drive side)
• 122 frame (operating side)
• 123 wave
• 124 cardan drive
• 125 gear
• 127 gear
• 126 output shaft
• 128 wave
• 129 contact bracket
• 130 contact bracket
• 131 mechanical means
• 132 mechanical means
• 133 screw spindle
• 134 screw spindle
• 135 operating lever
• 136 operating lever
• 137 bearings
• 138 bearings
• 139 bearings
• 140 bearings
• 141 wave
• 142 disc
• 143 disc
• 144 gear
• 145 gear
• 146 bolts
• 147 wave
• 148 contact bracket
• 149 contact bracket
• 150 clutch
• 151 wave
• 152 gear
• 153 gear
• 154 cones
• 155 floating mechanism
• 156 worm wheel
• 157 snail
• 158 housing
• 159 connecting rod
• 160 eccentric facility
• 162 axis
• 163 axis
• 171 electric motor
• 172 output shaft
• 173 gear
• 174 speed sensor
• 175 electrical connection
• 176 cruise control
• 177 speed sensor
• 178 electrical connection
• 179 switching device
• 180 tachometer generator
• 181 electrical connection
• 190 arrow
• 200 humidifier

300 humidifier

Claims (16)

1. Dampening device for a rotary printing machine, having a dipping roller (101) which is driven at a variable speed by an electric motor (111), the dipping roller (101) being coated with a hydrophilic material and partially dipping into a dampening-medium trough (107) containing dampening medium, having a metering roller (102) which is coated with elastomer and the rotational speed of which is dependent on that of the dipping roller (101), having a dampening distributor roller (103) coated with hydrophilic material, and having a dampening applicator roller (104) which is coated with elastomer and which is in contact with the dampening distributor roller (103) and with the plate cylinder (105) of the printing machine, characterized in that by virtue of a releasable coupling means (150) it is possible either for the dampening distributor roller (103) to be driven by the electric motor (111), such that a differential sliding occurs between the surfaces of the dampening distributor roller (103) and the dampening applicator roller (104), or for the dampening distributor roller (103) to be driven by the plate cylinder (105), such that a differential sliding occurs between the surfaces of the dampening distributor roller (103) and of the metering roller (102).

2. Dampening device according to Claim 1, characterized in that the shaft (141) of the dampening distributor roller (103) comprises a first gearwheel (144), meshing with the output shaft of the electric motor (111), and a second gearwheel (145) meshing with the shaft (151) of the plate cylinder (105), and by means of the releasable coupling means (150) the shaft (141) of the dampening distributor roller (103) can be connected fixedly in terms of rotation to the first gearwheel (144) or the second gearwheel (145), the other gearwheel in each case being supported movably on the shaft (141).

3. Dampening device according to Claim 2, characterized in that the releasable coupling means (150) comprise a disc (142, 143) which is arranged at each end of the shaft (141) of the dampening distributor roller (103), each disc (142, 143) being adjacent respectively to the first and the second gearwheel (144, 145), the coupling between the disc and the respective gearwheel (142, 144 and 143, 145 respectively) being made by means of connecting bolts (146).

4. Dampening device according to Claim 1, characterized in that the releasable coupling means (150) comprise locking means which prevent the simultaneous coupling of the dampening distributor roller (103) to the electric motor (111) and to the plate cylinder (105).

5. Dampening device according to Claims 3 and 4, characterized in that the connecting bolts (146) are provided in a number just sufficient to couple an individual disc (142, 143) to the respective gearwheel (144, 145), such that the two discs (142, 143) cannot be coupled simultaneously.

6. Dampening device according to Claim 1, characterized in that this comprises a further electric motor (171) of variable speed which drives the dampening distributor roller (103) directly, this electric motor running either at the speed of the metering roller (102) or at that of the plate cylinder (105).

7. Dampening device according to Claim 6, characterized in that this comprises a tachogenerator (180), mounted on the shaft (151) of the plate cylinder (105), and a rotational-speed transmitter (177, 174) connected to each of the electric motors (111, 171), the drive motor (171) of the dampening distributor roller (103) being equipped with an electronic control device which receives signals either from the rotational-speed transmitter (177) of the drive motor (111) of the dipping roller (101) or from the tachogenerator (180) of the plate cylinder (105).

8. Dampening device according to Claim 1, characterized in that the metering roller (102) likewise partially dips into a dampening-medium trough (107), and in that mechanical means (131, 132) are provided for radially displacing the shaft (123) of the dipping roller (101), the differential sliding occurring either between the surfaces of the dampening distributor roller (103) and the dampening applicator roller (104), when the dipping roller (101) is set away from the metering roller (102), or between the surfaces of the dampening distributor roller (103) and the metering roller (102), when the dipping roller (101) is brought into contact with the metering roller (102).

9. Dampening device according to Claim 8, characterized in that the mechanical means (131, 132) allowing the radial displacement of the shaft (123) of the dipping roller (101) comprise contact bars (129; 130) mounted rotatably in the stand (121, 122) of the printing machine, which contact bars are arranged on both sides of the dipping roller (101), and each of the contact bars (129, 130) has a positioning means (133, 135; 134, 136).

10. Dampening device according to Claim 9, characterized in that the contact bars (129, 130) rotate about an axis (162, 163) which extends coaxially relative to the shaft of the metering roller (102), the positioning means being designed in the form of a tommy screw (133, 135, 134, 136) extending through two bearings which are arranged on the respective shaft (123, 128) of the dipping roller (101) and that of the metering roller (102).

11. Dampening device according to one of Claims 1 to 10, characterized in that the dampening distributor roller (103) comprises a mechanism (155) - operable irrespective of the particular coupling mode of the dampening distributor roller (103) - which produces an axial distributing movement and moves the dampening distributor roller (103) with a defined axial travel.

12. Dampening device according to Claim 11, characterized in that the mechanism (155) producing an axial distributing movement comprises a worm wheel (156) and a worm (157).

13. Dampening device according to one of Claims 1 to 12, characterized in that this is supplemented by a bridging roller (115) which is arranged between the dampening applicator roller (104) and the next ink applicator roller (116), in one type of dampening or the other the bridging roller (115) making contact between the dampening applicator roller (104) and the ink applicator roller (116) and also coacting on the drive of the dampening applicator roller.

14. Dampening device according to Claim 13, characterized in that the bridging roller (115) is mounted movably.

15. Dampening device according to Claim 13, characterized in that the bridging roller (115) is driven at the speed of the plate cylinder (105).

16. Dampening device according to one of Claims 13 to 15, characterized in that the bridging roller (115) is mounted on the stand of the printing machine by means of an eccentric device which makes it possible to make or break contact between the bridging roller (115) and the dampening applicator roller (104).

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