Patent Publication Number: US-8534191-B2

Title: Printing press and method for operating a printing unit of a printing press

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority, under 35 U.S.C. §119, of German Patent Application DE 10 2007 049 916.9, filed Oct. 18, 2007; the prior application is herewith incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a method for operating a printing unit of a printing press in which, in a first operating mode, a printing unit cylinder and a distributor roller are driven rotationally by a first motor and the distributor roller is driven axially by a second motor and, in a second operating mode, the distributor roller is driven axially by the second motor. The present invention also relates to a printing press suitable for implementing this method. 
     In European Patent EP 1 167 026 B1, corresponding to U.S. Pat. No. 6,634,292, a printing press is described in which in a first operating mode a printing unit cylinder and a distributor roller are driven rotationally by a first motor and the distributor roller is driven axially by a second motor, and in a second operating mode the printing unit cylinder is driven rotationally by the first motor and the distributor roller is driven axially by the second motor. In the case of that prior art printing press, the distributor roller is driven rotationally by the second motor in the second operating mode. Two controllable clutches are required, which are comparatively expensive, in order to implement the two operating modes. 
     SUMMARY OF THE INVENTION 
     It is accordingly an object of the invention to provide a printing press and a method for operating a printing unit of a printing press, which overcome the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and which can be implemented less expensively. 
     With the foregoing and other objects in view there is provided, in accordance with the invention, a method for operating a printing unit of a printing press. The method comprises, in a first operating mode, rotationally driving a printing unit cylinder and a distributor roller with a first motor and axially driving the distributor roller with a second motor and, in a second operating mode, axially driving the distributor roller with the second motor and rotationally driving the distributor roller with a third motor. 
     With the objects of the invention in view, there is also provided a printing press, comprising a printing unit including a printing unit cylinder, a distributor roller, a first motor for rotationally driving the printing unit cylinder and the distributor roller in a first operating mode, a second motor for axially driving the distributor roller in the first operating mode and in the second operating mode, and a third motor for rotationally driving the distributor roller in the second operating mode. 
     One advantage of the invention is to be seen in the fact that the second clutch that is present in the prior art described at the outset is replaced by the third motor. It has turned out that electric motors which can be obtained on the market and which can be used as the third motor are less expensive than controllable clutches that are on the market. 
     In accordance with another mode of the invention, the first motor and the distributor roller have a clutch interposed which is kept engaged in the first operating mode and is kept disengaged in the second operating mode. This clutch can be the single clutch that is present for rotational driving of the inking unit of the printing unit. A further clutch provided for this purpose, which is present in the described prior art, is not required. 
     In accordance with a further mode of the invention, in the first operating mode the third motor is driven rotationally by the first motor. In this case, provision can be made in the first operating mode for the third motor to co-rotate without power in so-called generator operation. Instead, provision can also be made in the first operating mode for the third motor to be supplied with power in such a way that the third motor brakes the first motor. Through the use of the two variants, it is possible to achieve mutual preloading of gear wheels which are disposed between the first motor and the third motor. Through the use of this preloading of the gear wheels, their tooth flank or side contact is ensured, which is advantageous with regard to high printing quality. Likewise, it is possible to drive the third motor in such a way that in the first operating mode the third motor compensates for or at least minimizes rotational fluctuations caused by the first motor or the gear mechanism. 
     In accordance with an added mode of the invention, the first operating mode is the printing operation and the second operating mode is a maintenance operation. This maintenance operation can, for example, be a cleaning operation for washing the inking unit. 
     In accordance with an additional mode of the invention, in the second operating mode the printing unit cylinder is driven rotationally by the first motor. This can be provided for the case in which the inking unit and the printing unit cylinder are to be cleaned simultaneously in the second operating mode. Instead of this, however, provision can also be made for the first motor and the printing unit cylinder to remain stationary in the second operating mode while only the inking unit driven rotationally by the third motor is being cleaned. 
     In accordance with yet another mode of the invention, the printing unit cylinder is either an impression cylinder or a printing form cylinder. Likewise, provision can be made for an impression cylinder of the printing unit and a printing form cylinder of the printing unit to be connected to each other through a gear mechanism and to the first motor in such a way that both the impression cylinder and the printing form cylinder are driven rotationally by the first motor in both operating modes or at least in the first operating mode. If the printing press includes a plurality of printing units constructed in the manner described previously, the first motor can be a so-called main drive of the printing press, which drives all of the printing units in the manner described previously. This main drive of the printing press can be connected in parallel with a further main drive of the printing press, so that the printing unit cylinders, that is to say impression cylinders and printing form cylinders and, if appropriate, blanket cylinders, of the printing units are driven rotationally by a plurality of parallel-connected main drives in the two operating modes or at least in the first operating mode. According to another possible variant, the impression cylinders of the printing units are driven rotationally by the single main drive or the parallel-connected main drives, and the printing form cylinder of the respective printing unit is assigned a separate drive, which forms the first motor that drives the printing form cylinder and the distributor roller rotationally in the first operating mode and drives the printing form cylinder rotationally but not the distributor roller in the second operating mode. 
     The printing press according to the invention is preferably a sheetfed printing press, in which sheet printing material is printed in the first operating mode. The printing press is preferably a sheetfed rotary printing press for lithographic offset printing. 
     Other features which are considered as characteristic for the invention are set forth in the appended claims. 
     Although the invention is illustrated and described herein as embodied in a printing press and a method for operating a printing unit of a printing press, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
     The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE VIEW OF THE DRAWING 
       The FIGURE of the drawing is a schematic and block diagram of a preferred exemplary embodiment of a printing press containing further structurally and functionally advantageous developments for implementing the method according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now in detail to the single FIGURE of the drawing, there is seen a portion of a printing press  26 . A printing unit  27  for printing sheets  37  is illustrated in the drawing. The printing unit  27  includes a printing form cylinder  28  as a printing unit cylinder, a blanket cylinder  29  and an impression cylinder  30 . Furthermore, the printing unit  27  includes an inking unit  34  for inking the printing form cylinder  28 , and a dampening unit  35 . The dampening unit  35  includes a gearbox element which is illustrated in the drawing and dampening unit rollers which are not illustrated. 
     The inking unit  34  includes a ductor roller  33 , a first distributor roller  31  and a second distributor roller  32 . An ink fountain roller having an ink fountain, further distributor rollers, transfer rollers and ink applicator rollers are likewise constituent parts of the inking unit  34  but are also not illustrated in the drawing for reasons of better clarity. During printing operation, the ductor roller  33  swings back and forth between the aforementioned ink fountain roller and the first distributor roller  31 , so that the ductor roller  33  alternately comes into contact with the ink fountain roller and the first distributor roller  31 , in order to transfer the printing ink from the former to the latter. In order to implement this swinging movement, the ductor roller  33  is mounted in a lever, which is only symbolically illustrated in the drawing. The swinging movement of this lever is driven by a cam mechanism, which includes a radial control cam  18  and a cam roller fixed to the lever and running on the control cam  18 . 
     A first motor  21  is connected to a first gear wheel  1 , which has a drive connection through an intermediate gear mechanism  16  to a second gear wheel  2 . The first motor  21  is an electric motor and is the main drive of the printing press  26 . The second gear wheel  2 , which is disposed coaxially with the blanket cylinder  29  and is firmly connected so as to rotate with the latter, meshes with a third gear wheel  3  which is disposed coaxially with the printing form cylinder  28  and is firmly connected so as to rotate with the latter. A fourth gear wheel  4 , which meshes with a fifth gear wheel  5 , is fixedly seated on a shaft which connects the third gear wheel  3  to the printing form cylinder  28  firmly so as to rotate with the latter. 
     A second motor  22  is connected to a sixth gear wheel  6 , which meshes with a seventh gear wheel  7  and an eighth gear wheel  8 , that is to say it is in mutual tooth engagement therewith. The second motor  22  is an electric motor and is an additional drive, which is used to drive the axial oscillating movement of the distributor rollers and to drive the swinging movement of the ductor roller  33 . The seventh gear wheel  7  has a drive connection to the second distributor roller  32  through an oscillating gear mechanism  19 . The eighth gear wheel  8  is connected to the first distributor roller  31  by just such an oscillating gear mechanism  19 . The oscillating gear mechanisms  19  convert the rotational movements of the gear wheels  7 ,  8  into axial oscillating movements of the distributor rollers  31 ,  33  and are only symbolically indicated in the drawing. The eighth gear wheel  8  meshes with a ninth gear wheel  9 , which is disposed coaxially with the control cam  18  and firmly connected so as to rotate with the latter. The second motor  22  drives the rotation of the control cam  18  and thus the swinging ductor movement of the ductor roller  33  through the gear train including the gear wheels  6 ,  8 ,  9 . 
     A third motor  23  is connected to a tenth gear wheel  10 , which has a drive connection to an eleventh gear wheel  11  through an intermediate gear mechanism  17  indicated symbolically in the drawing. The third motor  23  is an electric motor and is used to drive the rotation of the distributor rollers  31 ,  32  and a distributor roller of the dampening unit  35 , which is not illustrated in the drawing. The intermediate gear mechanism  17 , like the intermediate gear mechanism  16 , is a gear train. The intermediate gear mechanism  17  includes a gear wheel which is disposed coaxially with the first distributor roller  31  and is firmly connected so as to rotate with the latter. The eleventh gear wheel  11  meshes with a twelfth gear wheel  12 , which is disposed coaxially with the second distributor roller  32  and firmly connected so as to rotate with the latter. The twelfth gear wheel  12  is seated fixedly on a shaft of the second distributor roller  32  and meshes with a thirteenth gear wheel  13 , which in turn meshes with a fourteenth gear wheel  14 . The fourteenth gear wheel  14  is disposed coaxially with the printing form cylinder  28  and, through a rotary bearing  24 , is rotatably mounted on that shaft on which the third gear wheel  3  and the fourth gear wheel  4  are fixedly seated. The fourteenth gear wheel  14  meshes with a fifteenth gear wheel  15 , which is a constituent part of a gear mechanism of the dampening unit  35 . The thirteenth gear wheel  13  is rotatably mounted, through a rotary bearing  38 , on a shaft  39  on which the fifth gear wheel  5  is fixedly seated. 
     The thirteenth gear wheel  13  can be connected firmly as required to the shaft  39  and thus to the fifth gear wheel  5  so as to rotate with them, through the use of a clutch  20  disposed between the fifth gear wheel  5  and the thirteenth gear wheel  13 . When the clutch  20  is engaged, the thirteenth gear wheel  13  is firmly connected to the shaft  39  and the fifth gear wheel  5  so as to rotate with them and, when the clutch  20  is released, the thirteenth gear wheel  13  is not firmly connected to the shaft  39  and the fifth gear wheel  5  so as to rotate with them. When the clutch  20  is disengaged, the thirteenth gear wheel  13  can rotate freely on the shaft  39 . The above-described cylinders, rollers and gear wheels and their shafts are rotatably mounted in a side wall  25  of a machine frame. 
     In addition, the printing press  26  includes an electronic control device  36 , which drives the motors  21 ,  22 ,  23  and the clutch  20  appropriately in operating modes explained below. The printing press  26  is operated as follows: 
     In a first operating mode, which is printing operation, the first motor  21  drives the rotations of the printing form cylinder  28  and of the blanket cylinder  29  through the gear wheels  1 ,  2 ,  3 . At the same time, the first motor  21  additionally drives the rotation of the impression cylinder  30  through a gear wheel belonging to the intermediate gear mechanism  16 . 
     In the first operating mode, the clutch  20  is engaged, so that the clutch  20  transmits the drive output of the first motor  21  from the fifth gear wheel  5  to the thirteenth gear wheel  13 . The drive output of the first motor  21  is transmitted from the thirteenth gear wheel  13  to the twelfth gear wheel  12 , which is disposed coaxially with the second distributor roller  32  and firmly connected so as to rotate with the latter. The drive output is transmitted from the twelfth gear wheel  12  through the eleventh gear wheel  11  to the gear wheel already mentioned, which is disposed coaxially with the first distributor roller  31  and firmly connected so as to rotate with the latter. This last-mentioned gear wheel is a constituent part of the intermediate gear mechanism  17  and is fixedly seated on the shaft of the first distributor roller  31 . The drive output of the first motor  21  is transmitted from the intermediate gear mechanism  17  to the third motor  23  through the tenth gear wheel  10 . 
     In the first operating mode, the third motor  23  can be driven by the control device  36  in such a way that the supply of electric power to the third motor  23  is prevented and the latter co-rotates with the tenth gear wheel  10  without power in a passive idle. According to another variant, in the first operating mode, the third motor  23  is supplied with electric power in such a way that, in this variant, in exactly the same way as in the passive idle variant mentioned previously, the first motor  21  dominates the third motor  23  or drives it rotationally in the first operating mode. 
     In the first operating mode, the second motor  22  drives the axial back and forth movement of the distributor rollers  31 ,  32  through the gear wheels  6 ,  7 ,  8  and the oscillating gear mechanism  19 . In this case, the control device  36  regulates the rotational speed of the second motor  22  in such a way that the distributor rollers  31 ,  32  execute a complete axial swing in each case within two complete revolutions of the printing form cylinder  28 . The operating personnel can continuously adjust a so-called distribution starting point of the distributor rollers  31 ,  32  on the control device  36 . During this adjustment, the rotational angle position of the second motor  22  relative to the rotational angle position of the first motor  21  is changed, so that the phase angle of the dead point of the axial swing of the distributor rollers  31 ,  32  relative to the rotational angle position of the printing form cylinder  28  is changed. In the first operating mode, in addition the ductor movement of the ductor roller  33  is driven by the second motor  22 , with the ductor roller  33  executing a complete swing in each case within three full revolutions of the printing form cylinder  28 . The ductor roller  33  is thus ⅓ turn, while the distributor rollers  31 ,  32  are ½ turn. 
     In a second operating mode, which is maintenance operation, the inking unit  34  and the dampening unit  35  are washed by a cleaning apparatus, which is not illustrated in the drawing and which belongs to the printing unit  27 . In the second operating mode, the axial oscillating movement of the distributor rollers  31 ,  32  is driven by the second motor  22  in the same way as in the first operating mode. In the second operating mode, the clutch  20  is disengaged, so that the thirteenth gear wheel  13  is no longer firmly connected to the shaft  39  and the fifth gear wheel  5  so as to rotate with them. When the clutch  20  is disengaged, the thirteenth gear wheel  13  is able to rotate around the shaft  39  and relative to the fifth gear wheel. Thus, in the second operating mode, no drive output or rotational movement can be transmitted from the first motor  21  to the distributor rollers  31 ,  32  and the third motor  23 . 
     In the second operating mode, the rotation of the distributor rollers  31 ,  32  is driven by the third motor  23 , with the drive output of the third motor  23  being transmitted through the tenth gear wheel  10  and the intermediate gear mechanism  17  to the shaft of the first distributor roller  31 , and being transmitted from the intermediate gear mechanism  17  through the eleventh gear wheel  11  and the twelfth gear wheel  12  to the shaft of the second distributor roller  32 . In the second operating mode, the first motor  21  can remain stationary or the rotational movement of the printing unit cylinders  28 ,  29 ,  30  or one of these cylinders can be driven by the first motor  21 . For example, the ratio of the rotational speed of the distributor rollers  31 ,  32  relative to the rotational speed of the printing unit cylinders  28  to  39  can be different than in the first operating mode.