Abstract:
A first roller, which takes up dampening fluid from a dampening agent reservoir, and a second roller, are controlled. The first roller transfers the dampening fluid to the second roller. The first roller and the second roller have separate driving devices and their individual surface velocities differ from each other because of their separate driving devices. A change in the velocity of a form cylinder results in a change in the slip between the first and second rollers. Dampening systems are also contemplated.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is the U.S. national phase, under 35 USC 371, of PCT/DE2003/004038, filed Dec. 9, 2003; published as WO 2004/054804 A1 on Jul. 1, 2004, and claiming priority to DE 102 58 326.9 filed Dec. 13, 2002, the disclosures of which are expressly incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention is directed to methods for controlling a first roller, which takes up a dampening agent from a dampening agent source, and a second roller and to dampening units. The rollers are part of a roller train which is used for conveying the dampening fluid to the forme cylinder. 
     BACKGROUND OF THE INVENTION 
     A dampening unit is known from U.S. Pat. No. 3,168,037. Either a fountain roller, which takes up the dampening agent from a dampening agent reservoir, or a transfer roller which is rolling off on the fountain roller, are driven by a controllable drive mechanism in such a way that a rotating speed of these two rollers can be changed. However, the magnitude of the rotating speed of these two rollers is always identical. 
     A dampening unit is known from U.S. Pat. No. 3,986,452. A fountain roller, taking up a dampening agent from a dampening agent reservoir, and at least one further roller, which is in roller-to-roller contact with the fountain roller, have controllable drive mechanisms, each of which drive mechanisms is independent of the other. This further roller is in a roller-to-roller contact with a dampening agent application roller that is placed against a forme cylinder. A traversing bridge roller is placed against the dampening agent application roller. 
     A dampening unit, with a fountain roller taking up a dampening agent from a dampening agent reservoir and with a slip roller rolling off on the fountain roller, is known from EP 0 893 251 A2. Both rollers can be driven by separate drive mechanisms, if required. Both rollers always have the same surface speed. 
     A film-type dampening unit for rotary printing presses is known from EP 0 462 490 A1. In a roller train extending from a dampening agent tank as far as the forme cylinder and consisting of three or four rollers, a fountain roller and a metering roller are driven together by a first electric motor. A dampening agent distribution roller following the metering roller in the roller train is additionally moved axially back and forth by a mechanism. A bridge roller is placed against a dampening agent application roller which is placed against the dampening agent distribution roller and the forme cylinder. 
     A dampening unit of an offset rotary printing press is known from DE 29 32 105 C2. The dampening unit has a roller train, consisting of three rollers, extending from the dampening agent pick-up up to the forme cylinder. Each one of the three rollers is driven independently of each other by a controllable electric motor, each of which controllable electric motor preferably can be set in an infinitely variable manner. 
     A drive mechanism for the dampening unit of an offset printing press is known from DE 38 32 527 C2. A traversing bridge roller is provided, which is simultaneously placed against a dampening agent application roller and an ink application roller. The bridge roller is pneumatically driven. Its number of revolutions is controlled by changing the pneumatic pressure. 
     A dampening unit for a printing press is known from DE 299 00 216 U1. A first roller, which takes up a dampening agent, and a second roller, which is connected with the first roller for transferring dampening agent, are provided. Both of these rollers are rotatably driven. A slippage between the two rollers exists, which slippage can be set by a control device when the dampening unit is operated. 
     Drive mechanisms for a printing group are known from WO 03/039873 A1. The rotatory driving device and the traversing driving device of a roller are arranged on opposite ends of the roller. 
     A dampening unit of an offset rotary printing press is known from JP-A-01 232 045. The dampening unit has a roller train consisting of three rollers that are positioned extending from the dampening agent pick-up up to the forme cylinder. The fountain roller, which is the first roller, as well as the transfer roller which is the second roller are driven independently of each other, each by a controllable motor. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is directed to providing a method for controlling a first roller, which takes up a dampening agent from a dampening agent source, and a second roller. 
     In accordance with the present invention, the object is attained by the provision of a roller train that conveys dampening fluid from a source of dampening fluid to a forme cylinder in a printing press. The roller train includes at least first and second rollers, the first of which contacts the dampening fluid and the second of which is in contact with the first. Each of these at least two rollers has its own separate drive motor. The first and second rollers are a roller train that may include other rollers which may also have their own drive sources. Surface speeds of the at least first and second rollers may be different from each other. 
     The advantages to be gained by the present invention lie, in particular, in that the first or fountain roller and an adjacent second dampening agent transfer roller can be controlled completely independently of each other. The slippage that is formed between them, because of an intentional difference in their surface speeds, is adjustable as may be needed, for accomplishing a correct metering of a dampening agent which is to be applied to the rollers. The adjustment of the slippage takes place, in particular, as a function of a change of the surface speed of the forme cylinder. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the present invention are represented in the drawings and will be described in greater detail in what follows. 
       Shown are in: 
         FIG. 1 , a dampening unit with four rollers in a roller train extending to the forme cylinder in accordance, with the present invention, and in 
         FIG. 2 , a dampening unit with three rollers in a roller train extending to the forme cylinder also in accordance with the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In somewhat schematic representations,  FIGS. 1 and 2  each show a dampening unit  01 , preferably a film-type dampening unit  01  in accordance with the present invention and, with a first roller  04  and a second roller  06 . The first roller  04  takes up a dampening agent  02 , such as, for example, water  02  or an alcohol-water mixture  02  from a dampening agent source  03 , such as, for example, a dampening agent reservoir  03 , and, in particular, a dampening agent tank  03 , or from a dampening agent trough  03 . The first roller  04  transfers at least a portion of the dampening agent  02  directly to the second roller  06 , which is arranged adjacent to the first roller  04 . Therefore, the first roller  04  is preferably embodied as a fountain roller  04  or as a duct roller  04 . Alternatively, the dampening agent source  03  can be embodied as, for example, a spray crosspiece  03  with a least one spray nozzle  03 , which sprays the dampening agent  02  onto the first roller  04 , and wherein the dampening agent  02  is now applied to the first roller  04  in the form of finely distributed droplets. Further possible configurations provide for embodying the dampening unit  01  as a brush dampening unit or as a centrifugal dampening unit, with which the dampening agent  02  is also applied to the first roller  04  in a contactless manner. The second roller  06  can be a metering roller  06 , a dampening agent transfer roller  06  or a distribution roller  06 , each one of which is preferably provided with a chrome-plated surface, or with a ceramic-coated surface. The first roller  04  is the first of several rollers in a roller train, over which the dampening agent  02  is conveyed from the dampening agent reservoir  03  to the forme cylinder  09  of a printing press operated by the offset printing process, to which the dampening unit  01  has been assigned. The two embodiments of the present invention, as depicted in  FIGS. 1 and 2 , differ, in particular, in the number of rollers which are arranged in the roller train. 
     The printing press is configured as, for example, a jobbing printing press. Its printing group has at least one forme cylinder  09  and one transfer cylinder, which is not specifically represented, and wherein these two cylinders roll off on each other. A jobbing printing press, and preferably a jobbing printing press which is operating using the offset printing method, is understood to be a printing press with a forme cylinder  09 , wherein only a single printing forme is arranged on its forme cylinder  09  in the axial direction of the forme cylinder, wherein the printing forme preferably has several print image locations in a direction extending axially in respect to the forme cylinder  09 , and wherein the print image locations are not in a predetermined format, so that these print image locations can have any arbitrary width within defined limits, in particular in a direction extending axially with respect to the forme cylinder  09 . 
     To attain a good printing result, dampening units  01 , which use a dampening agent  02  to which dampening agent  02 , for example for reducing environmental stress or for the reduction of its cost, preferably no alcohol at all, or only very little alcohol and, in particular isopropyl alcohol (IPA) of clearly less than 5% of the volume of all the matter added to the dampening agent  02  as a whole has been added, require a very precise setting of the amounts of dampening agent  02 . This precise setting of the amount of dampening agent  02  is matched to the respective production speed of the printing press and to the amount of dampening agent  02  that is to be conveyed to the forme cylinder  09  during the production of the printing press, i.e. while it is printing. To make matters worse, it is necessary to accomplish an increasingly higher production speed of the printing presses. Today&#39;s printing presses easily attain a production speed of their printing group cylinders in the range of 70,000 to 80,000 revolutions per hour. If the diameters of the transfer cylinders and of the forme cylinders  09 , which are in operative contact with each other, are identical, the production speed of the printing press corresponds to the surface speed v 09  of the forme cylinder  09 . The dampening unit  01 , with the characteristics which will be described in what follows, assures the transport of a sufficient amount of dampening agent  02 , which amount can be exactly metered, even at such high production speeds. 
     Furthermore, the amount of the dampening agent  02  which is required at the forme cylinder  09  for attaining good printing results is a function of the emulsification properties of the ink used and of the amount of ink required for producing the printed product. The ink and the dampening agent  02  form a mixture in which depending on the condition of the ink, a volumetric portion of the amount of the dampening agent  02 , which can be varied within defined limits, can be mixed together with the ink. The ink switched back into the dampening unit  01  can absorb the dampening agent  02  in amounts between 15% and 25%, for example. The amounts absorbed increase with an increase in the surface speed v 09  of the forme cylinder  09 . However, a threshold value for the amount of dampening agent  02  emulsified by the ink is set because, for example, the ink which is imprinted on a material to be imprinted, such as, for example, a paper web, must dependably dry in the course of the passage of the material to be imprinted through a drying unit, such as, for example, a headset dryer, which is arranged downstream of the printing group. Because of the desired high production speed of the printing press, of 12 m/s or more, the retention time of the material to be imprinted in the drying unit is very short. 
     The more colored print image locations a printed product has, the more ink is needed at the forme cylinder  09 . Accordingly, to set a required balance between ink and dampening agent  02 , it is also necessary, in such a case, to make available a greater amount of dampening agent  02  at the forme cylinder  09  if a more color-intensive printed product is produced by the printing press. Therefore, to obtain a satisfactory printing result, the dampening unit  01 , with the characteristics to be described in what follows, matches the amount of dampening agent  02  made available at the forme cylinder  09  also as a function of the condition of the ink and as a function of the amounts of the ink required for the printed product to be formed. 
     In order to make possible an adaptation of the requirements of the amounts of dampening agent  02  made available at the forme cylinder  09 , as a function of the production speed of the printing press and as a function of the balance between ink and dampening agent  02  to be set, the first roller  04  and the second roller  06  have separate drive mechanisms  07 ,  08 , which can be controlled independently of each other. Drive mechanisms  07 ,  08  for the first roller  04  and for the second roller  06  respectively, which drive mechanisms  07 ,  08  can be controlled independently of each other, have the advantage that a surface speed v 04  of the first roller  04 , as generated by the drive mechanism  07 , and a surface speed v 06  of the second roller  06 , as generated by the drive mechanism  08 , do not rigidly follow a parameter affecting the amount of dampening agent  02 . Instead, for accomplishing a matching of the amounts of dampening agent  02  to be conveyed, the ratio of the surface speeds v 04 , v 06  with respect to each other, can also be variably set according to the requirements, by which variation the metering of the dampening agent  02  to be conveyed by the dampening unit  01  is considerably affected. As a function of the actually existing printing process, and for the same value of the surface speed v 09  of the forme cylinder  09 , different settings of the surface speed v 04  of the first roller  04  and of the surface speed v 06  of the second roller can result, as well as differences regarding their ratio with respect to each other. 
     As a rule, the surface speed v 04  of the first roller  04 , as generated by the first drive mechanism  07 , and the surface speed v 06  of the second roller  06 , as generated by the second drive mechanism  08  are different from each other. Preferably, the surface speed v 04  of the first roller  04  is less than the surface speed v 06  of the second roller  06 . The surface speeds v 04 , v 06  can be set independently of each other and can both be set variably. In a preferred embodiment of the present invention, the surface speed v 06  of the second roller  06  lies, for example, between twice and four-and-a half times, and in particular is three times that of the surface speed v 04  of the first roller  04 . The magnitude of the surface speed v 04  of the first roller  04  is limited by the requirement that the first roller  04  must dependably pick up the dampening agent  02  out of the dampening agent reservoir  03  on its surface. Experience has shown that, at a surface speed v 04  of the first roller  04 , starting at more than 2 m/s, the dependable pickup of dampening agent  02  is no longer assured. At surface speeds above that value, considerable amounts of the dampening agent  02  are flung off the surface of the first roller  04 . Therefore, the surface speed v 04  of the first roller  04  is preferably set to values which are lower than its upper limit speed, such as, for example, to a value of at most 1.5 m/s. In contrast to this, the surface speed v 09  of the forme cylinder  09  lies in a range of 12 m/s to 15 m/s, for example. 
     If the surface speed v 06  of the second roller  06  is greater than the surface speed v 04  of the first roller  04 , which as a rule, is the case, a slippage exists between the first roller  04  and the second roller  06 , because the surface speed v 04  of the first roller  04  lags behind the surface speed v 06  of the second roller  06 . This slippage, which is formed by a ratio of the two surface speeds v 04 , v 06  of the two rollers  04 ,  06 , can be variably set by the use of the drive mechanisms  07 ,  08  of the first roller  04  and of the second roller  06 , which drive mechanisms  07 ,  08  are independent of each other. 
     The amount of dampening agent  02  which is to be conveyed by the roller train of the dampening unit  01  must be adjusted as a function of a change of the surface speed v 09  of the forme cylinder  09  which is driven by a further, separate drive mechanism  18 , such as, for example, when increasing the surface speed v 09  of the forme cylinder  09 , for example when increasing the surface speed v 09  from a set-up speed of the printing press to its production speed. For example, the set-up speed of the printing press lies between 1.7 m/s and 3.4 m/s, and preferably lies between 2 m/s and 2.6 m/s, and therefore amounts to between 11% and at most to 25% of the production speed of the printing press, or the surface speed v 09  of the forme cylinder  09 . Thus, to reach the production speed, the surface speed v 09  of the forme cylinder  09  is increased by a magnitude of between four times to nine times, starting from the set-up speed. A rapidly reacting dampening system unit  01 , which can be matched to the requirements of the dampening agent  02  to be conveyed, is therefore required for such a large increase in speed. In the same way, the conveyed amount of dampening agent  02  must also be adjusted during a period of start-up of the printing press from its stopped state, or when the production speed is being reduced. Moreover, as previously mentioned, the actual requirement for dampening agent  02  is a function of the amount of ink needed for the production of the printed product. In many cases of application, and in particular in connection with printing presses with a large increase in speed, a sufficient reaction to this matching requirement is not always possible with a rigid coupling, such as, for example, with a gear coupling between the first roller  04  and the second roller  06 . 
     To provide the required matching, the number of revolutions of the drive mechanisms  07 ,  08  of the first and second rollers  04 ,  06 , respectively of the dampening unit  01  are controllable, and preferably are infinitely variably controllable, and in particular are electronically controllable. Control of the numbers of revolution can be performed remotely, such as, for example, from a control console that is assigned to the printing press. The drive mechanisms  07 ,  08  for the first roller  04  and for the second roller  06 , respectively are preferably embodied as electric motors  07 ,  08 , such as, for example, a.c. or d.c. motors  07 ,  08 , or as frequency-controlled, multiphase a.c. motors  07 ,  08 . The drive mechanism  18  of the forme cylinder  09  can also be embodied as an electric motor  18 , such as, for example, an a.c. or a d.c. motor  18  or as a frequency-controlled multiphase a.c. motor  18 . In a manner that is the same as the drive mechanisms  07 ,  08  of the rollers  04 ,  06  of the dampening unit  01 , this motor  18  can also be controllable. The drive mechanism  18  of the forme cylinder  09  is independent of the drive mechanisms  07 ,  08  of the rollers  04 ,  06  of the dampening unit  01 . There is no positive connection between the drive mechanisms  07 ,  08  of the rollers  04 ,  06  and the drive mechanism  18  of the forme cylinder  09 . It is not a requirement that the drive mechanism  18  of the forme cylinder  09  only drives the forme cylinder  09 . The drive mechanism  18  can transfer the torque it has generated at least to the forme cylinder  09 , and possibly also to the transfer cylinder, which is not specifically represented, and which works together with the forme cylinder  09 . 
     If required, the control device for the drive mechanisms  07 ,  08 ,  18  can be expanded into a regulating device by adding a positive feedback device, that is picking up an actual value, and an evaluation device for evaluating a feed-back signal. The actual value of a number of revolutions of the rollers  04 ,  06  or of the forme cylinder  09  is detected, for example, by the use of a sensor which is providing an electrical output signal. The control or the regulation of the drive mechanisms  07 ,  08  is preferably performed with the aid of a suitable computing unit which is not specifically represented, and which, for example, predetermines a corridor for advantageous setting values. 
     The first roller  04  and the second roller  06  of the dampening unit  01  constitute the first and second rollers in the roller train that is conveying the dampening agent  02  to the forme cylinder  09 . The surface speed v 04  of the first roller  04  and the surface speed v 06  of the second roller  06  can be set independently of each other and each without a rigid dependence on the surface speed v 09  of the forme cylinder  09 . As a rule, the surface speed v 04  of the first roller  04 , or the surface speed v 06  of the second roller  06  are both less than the surface speed v 09  of the forme cylinder  09 . 
     In a first operating state of the dampening unit  01 , it is possible to provide an operating mode so that the surface speed v 09  of the forme cylinder  09  and the surface speed v 06  of the second roller  06  are at a first ratio with respect to each other, while in a second operating state of the dampening unit  01 , the surface speeds v 09 , v 06  are at a second ratio with respect to each other. The surface speed v 09  of the forme cylinder  09  can have the same value during both of the operating states of the dampening unit  01 , or alternatively can assume values which differ from each other. 
     The roller train to the forme cylinder  09  can be expanded by the addition of a third roller  11 , or also by the addition of a fourth roller  13 , wherein the third roller  11  is placed downstream of the second roller  06  and the fourth roller  13  is placed downstream of the third roller  11 . The third roller  11  is coupled, for example by the use of a set of gears  12 , such as, for example, a gear wheel drive  12  or a belt drive  12 , with the second roller  06 . Alternatively, driving of the third roller  11  can take place by friction, for example at the second roller  06 , or by friction with the forme cylinder  09 . The surface speeds of the several rollers provided in the roller train extending from the dampening agent reservoir  03  to the forme cylinder  09  has been respectively set in such a way that there is slippage between the second roller  06  and the third roller  11 , or between the third roller  11  and the fourth roller  13 . The slippage between the first roller  04  and the second roller  06  can be, for example, 1:3, wherein the first roller  04  rotates slower than the second roller  06 . The slippage between the second roller  06  and the third roller  11  can be selected to be considerably greater, wherein, for example, the third roller  11  rotates very much faster than the second roller  06 . 
     For accomplishing an improved distribution of the dampening agent  02  on the surfaces of the rollers  06 ,  11 ,  13  which are arranged in the roller train, and for preventing patterning, at least one of these rollers  06 ,  11 ,  13 , which follow the first roller  04  in the roller train, can be embodied to also perform traversing movements. It is advantageous to decouple or to separate the traversing drive mechanism  19  provided for this purpose from the rotatory drive mechanisms  07 ,  08  of the rollers  06 ,  11 ,  13  and to configure it to be controllable independently of the latter. The frequency of the traversing movement, in particular, can be freely selected. The length of the traversing movement is for example ±8 mm. However, it is also possible to provide a variably adjustable length for the traversing movement of, for example, between 0 mm and 16 mm. The traversing drive mechanism  19  is embodied, for example, as an electrical motor  19 , such as, for example, a linear motor  19 . The roller  11  or  13 , which is transferring the dampening agent  02  to the forme cylinder  09 , is, in particular, driven by friction by the forme cylinder  09 . 
     An inking unit  16 , with at least one ink application roller  17  which can be placed against the forme cylinder  09 , is assigned to the forme cylinder  09 . The inking unit  16  inks a printing forme, which is not specifically represented and which is mounted on the surface of the forme cylinder  09  by use of the ink application roller  17 . The roller  06  or  11  or  13  which is primarily applying the dampening agent  02  to the forme cylinder  09 , and, depending on the embodiment of the roller train, which is the second roller  06 , the third roller  11  or the fourth roller  13 , can then advantageously be placed simultaneously against the forme cylinder  09  and also against the ink application roller  17 , or against an ink distribution roller of the inking unit  16  which is working together with the forme cylinder  09 . The placement of the roller  06 ,  11  or  13 , which applies the dampening agent  02  to the forme cylinder  09 , against the ink application roller  17  can therefore occur either directly or can occur indirectly, for example via a bridge roller  14  which is embodied as an ink distribution roller  14 . In connection with a dampening unit  01  that is configured with four rollers  04 ,  06 ,  11 ,  13  in the roller train in particular, it is also possible to provide a further second bridge roller  23 , that is represented in dashed lines in  FIG. 1  and which is placed upstream of the first bridge roller  14 , wherein the upstream located bridge roller  23  is arranged between the first bridge roller  14  and the third roller  11 , i.e. the roller  11  which, in the roller train, is arranged upstream of the fourth roller  13 , which fourth roller  13  applies the dampening agent  02  to the forme cylinder  09 . Preferably, the first bridge roller  14  is seated in a frame, which is not specifically represented, and is movable by at least one actuating device, such as, for example, by a remote-controlled working cylinder, and in particular by a pneumatic cylinder which is not specifically represented, in such a way that it can selectively assume, for example while being controlled from a control console, one of four operating positions as described in what follows. In one operating position the first bridge roller  14  is placed against the ink application roller  17  and not against the roller  06 ,  11  or  13  which is applying the dampening agent  02  to the forme cylinder  09 . In another, second operating position, the bridge roller  14  is placed against the roller  06 ,  11  or  13  which is applying the dampening agent  02  to the forme cylinder  09  and not against the ink application roller  17 . In a further or third operating position, the bridge roller  14  is placed simultaneously against the roller  06 ,  11  or  13  that is applying the dampening agent  02  to the forme cylinder  09  and also against the ink application roller  17 , which is its normal operating position, and wherein the bridge roller  14  can be additionally moved into the other operating positions. The bridge roller  14  furthermore can be simultaneously removed from contact with the roller  06 ,  11  or  13  which is applying the dampening agent  02  to the forme cylinder  09  and from contact with the ink application roller  17 . The bridge roller  14  is placed into contact if it is touching one of the rollers  06 ,  11  or  13  which is applying the dampening agent  02  to the forme cylinder  09 , and/or if it is touching the ink application roller  17 , or is at least in an operative contact with them, for conveying the ink or the dampening agent  02 . It is removed out of contact if its surface does not touch the surface of one of the rollers  06 ,  11  or  13 , or if the surfaces of the rollers  06 ,  11  or  13  are at least not in operative contact for conveying the ink or the dampening agent  02 . The upstream positioned bridge roller  23  can also have several operating positions by being either in contact with the first bridge roller  14  or with the third roller  11  of the roller chain, or by being removed from contact with at least one of these rollers  11 ,  14 , wherein at least one actuating device, which is not specifically represented, such as, for example, a working cylinder, and in particular a pneumatic cylinder, is provided. The actuating device moves the upstream located bridge roller  23  from one operating position into the other operating position. The operation of this actuation device can preferably also take place by remote control, and in particular can be accomplished from the control console. 
     Upon contact between the rollers, a flattened contact strip of a width of between 3 mm and 8 mm, and preferably of between 5 mm and 6 mm, is formed extending in the axial direction of, and between the rollers  04 ,  06 ,  11 ,  13  on their surfaces. The flattened contact strip between the roller  06 ,  11 , or  13  which is applying the dampening agent  02  to the forme cylinder  09 , or between the ink application roller  17  and the forme cylinder  09 , can have a width of from 8 mm up to 10 mm. The contact force between the rollers  04 ,  06 ,  11 ,  13 ,  17  and the forme cylinder  09  is set, for example manually, by the use of an adjusting spindle, preferably through a path change, wherein the set width of the contact strip remains unchanged during the printing process. If the width of the contact strip is to be changeable during the printing process, it is advantageous to perform the setting of the rollers  04 ,  06 ,  11 ,  13 ,  17  by the use of a roller lock, which roller lock performs, while, for example, being remotely controlled preferably by actuation from the control console, a radial lift. As a rule, the setting of the width of the contact strip takes place independently of the surface speed v 09  of the forme cylinder  09 . 
     The bridge roller  14  is preferably structured so that it is able to perform traversing movements and is driven, for example, by a traversing drive mechanism  21 , which is preferably embodied as a controllable motor  21 , such as, for example, a linear motor  21 , and which is preferably independently of its rotatory movement. A further drive mechanism  22  for the bridge roller  14 , which is independent of the other drive mechanisms  07 ,  08 ,  18 , can be provided as, for example, a motor  22 , preferably an a.c. or d.c. motor  22  or a frequency-controlled multiphase a.c. motor  22 , and in particular as an electrical motor  22  which can be remote-controlled. 
     If the roller  11  or  13 , which is applying the dampening agent  02  to the forme cylinder  09 , is driven by friction, this roller  11  or  13  can be seated in the frame in such a way that an axial or transverse lift or displacement of, for example, 3 mm to 4 mm, is possible. This lift or axial displacement is performed in that roller  11  or  13  is taken along by the traversing movement of the bridge roller  14 . Preferably no, or only a minimal slippage of less than 2%, and preferably of less than 1%, exists between the roller  11  or  13 , which is applying the dampening agent  02 , and the forme cylinder  09 . As an alternative to frictional driving, and in connection with special applications, it is, however, also possible to provide the roller  11  or  13 , which is applying the dampening agent  02  to the forme cylinder  09 , with its own drive mechanism, which is not specifically represented, for the rotatory movement, which dampening agent application roller drive mechanism is independent of the other drive mechanisms  07 ,  08 ,  18 ,  22 , and which may be, for example a motor, and preferably may be an a.c. or a d.c. motor or a frequency-controlled multiphase a.c. current motor. 
     To change the dampening unit  01  between a first operating mode, for “direct dampening,” and a second operating mode, for “indirect dampening,” the roller  11  or  13 , that is used for applying the dampening agent  02  to the forme cylinder  09 , can be placed against the bridge roller  14  or can be moved away from it. For this purpose, the roller  11  or  13 , which is applying the dampening agent  02  to the forme cylinder  09 , which, in this case, is the roller  13 , is represented in two operating positions, as is shown in  FIG. 2 . In the dot-dash line representation, the roller  13  has been moved away from the bridge roller  14 . To move the roller  11  or  13 , which is applying the dampening agent  02  to the forme cylinder  09 , into its desired operating position, at least one actuating device, which is not specifically represented, and which preferably is remote-controlled, for example from the printing press control console, is provided, for example as a working cylinder, and preferably as a pneumatic cylinder. This actuating device brings the roller  11  or  13 , that is applying the dampening agent  02  to the forme cylinder  09 , into one of the two operating positions with respect to the bridge roller  14 , or moves it away from the forme cylinder  09 . The roller  11  or  13 , which is applying the dampening agent  02  to the forme cylinder  09 , can be seated in eccentric bushings, for example, and in which eccentric bushings the roller  11  or  13 , which is applying the dampening agent  02  to the forme cylinder  09 , can be moved into its desired operating position by the actuating device. The operating mode characterized as “direct dampening” is selected if the roller  11  or  13 , which is applying the dampening agent  02  to the forme cylinder  09 , is placed against the forme cylinder  09  and is moved away from the bridge roller  14 . In this mode of operation the roller  11  or  13 , which is applying the dampening agent  02  to the forme cylinder  09 , only applies the dampening agent  02  to the forme cylinder  09 . The mode of operation characterized as “indirect dampening” is selected if the roller  11  or  13 , which is applying the dampening agent  02  to the forme cylinder  09 , is simultaneously placed against both the forme cylinder  09  and the bridge roller  14 . During this “indirect dampening,” the roller  11  or  13 , which is applying the dampening agent  02  to the forme cylinder  09 , also conveys a not inconsiderable amount of ink that is coming from the inking unit  18  to the forme cylinder  09 . 
     The first roller  04  and the second roller  06  can be moved together away from the roller  11  or  13 , which is applying the dampening agent  02  to the forme cylinder  09 . For this purpose, the first roller  04  and the second roller  06  can be seated in a common support, which is not specifically shown. The common support has a rotating point, around with the support can be rotated, so that the first roller  04  and the second roller  06  together pivot away from the roller  11  or  13 , which is applying the dampening agent  02  to the forme cylinder  09 . 
     The surface of the first roller  04  consists, for example, of an elastomeric material, preferably rubber, and in particular consists of a material of a hardness between 20 and 30 Shore A, and preferably of approximately 25 Shore A. The surface of the second roller  06  consists of, for example, a ceramic material or of a chromium-containing material, and where a coating of a chromium-containing material has been applied to a roller core of a metallic material, for example. The surface of the roller  11  or  13 , which is applying the dampening agent  02  to the forme cylinder  09 , in turn consists of, for example, an elastomeric material, preferably rubber, and in particular of a material of a hardness between 25 and 40 Shore A, and preferably of approximately 35 Shore A. The surface of the roller  11  or  13 , which is applying the dampening agent  02  to the forme cylinder  09 , is therefore made harder than the surface of the first roller  04 . The surface of the second roller  06  is preferably selected to be very much harder, for example harder by a factor of ten, than the surface of the first roller  04  or the surface of the roller  11  or  13 , which is applying the dampening agent  02  to the forme cylinder  09 . The surface of the bridge roller  14  is made of a plastic material, for example, and is preferably preferably made of Rilsan. However, the surface of the upstream located second bridge roller  23  can consist of an elastomeric material, preferably of rubber. 
     The ratio of the surface speed of the forme cylinder  09  with respect to the surface speed of the roller  13  applying the dampening agent  02  to the forme cylinder  09 ; with respect to the surface speed of the third roller  11 ; with respect to the surface speed of the second roller  06 ; and with respect to the surface speed of the first roller  04  are, for example, like 1 to between 1 to 0.98; to between 0.4 to 0.98; to between 0.25 to 0.4 and to between 0.08 to 0.18, and are preferably 1 to 0.99 to 0.96 to 0.33 to 0.1. If only three rollers in the roller train between the forme cylinder  09  and the dampening agent reservoir  03  are being used, the slippage ratio, which was separately mentioned above for the third roller  11 , can be omitted, because the roller  11  is now already the roller applying the dampening agent  02  to the forme cylinder  09 . 
     While preferred embodiments of methods for controlling both a first roller, which takes up dampening agent from a dampening agent source, as well as a second roller, and dampening systems in accordance with the present invention have been set forth fully and completely hereinabove, it will be apparent to one of skill in the art that various changes in, for example, the specific structure of the printing press, the type of material to be printed, and the like could be made without departing from the spirit and scope of the present invention which accordingly is to be limited only by the appended claims.