Abstract:
A method for driving a printing press having, (i) an impression cylinder, (ii) at least one cylinder group having (a) a blanket cylinder, (b) a printing form cylinder, and (1) an imaging device, (2) an inking unit, and (3) an inherent drive system, all for said printing form cylinder, (iii) a sheet feeding device, (iv) a sheet delivering device, (v) a drive wheel train connecting the cylinders and the inking unit, and (vi) optionally a main motor drive, the method comprising detaching the printing form cylinder from the drive wheel train, driving the printing form cylinder by the inherent drive system at imaging speed during image formation, and re-attaching the printing form cylinder after image formation to the drive wheel train in an operating phase position.

Description:
This is a continuation of international application No. PCT/DE98/01528, filed on Jun. 2, 1998. 
    
    
     FIELD OF INVENTION 
     The invention relates to a method and device for driving a printing press with an integrated imaging device. 
     BACKGROUND OF INVENTION 
     A printing press with an impression cylinder, a blanket cylinder, a printing form cylinder, an inking unit and imaging device allocated to the printing form cylinder is known from e.g. German patent No. 195 15 077 A1. These elements are connected with each other by a gear train. The inking unit can be detached from the gear train for the image formation on the printing form cylinder. 
     A disadvantage of this procedure is that the image formation takes a longer time because the imaging speed, i.e. the rotating speed of the printing form cylinder during the image formation, is identical with the maximum printing speed. 
     BRIEF DESCRIPTION OF INVENTION 
     It is an object of the present invention to provide a method and a device enabling higher imaging speed and therefore minimizing the time required for image formation. Accordingly, the present invention provides a method and a device enabling a high imaging speed and minimizing the image formation time. 
     According the present invention the printing form cylinder drive is detached from the drive wheel train, and the printing form cylinder is driven by a dedicated drive at imaging speed during image formation and the printing form cylinder is attached to the drive wheel train in the operating phase position. Thus the present invention provides a method for driving a printing press having (i) an impression cylinder, (ii) at least two cylinder groups each having (a) a blanket cylinder, (b) a printing form cylinder, and (1) an imaging device, (2) an inking unit, and (3) and dedicated drive, all for said printing form cylinder, (iii) a sheet feeding device, (v) a drive wheel train connecting said cylinders and said inking unit, and (vi) a main motor drive, the method comprising detaching the printing form cylinder from said drive wheel train, driving said printing form cylinder by said dedicated drive at imaging speed during image formation, and re-attaching said printing form cylinder after image formation to said drive wheel train in an operating phase position. 
     As used throughout the disclosure and the claims, any reference to a “dedicated drive” means a separate, own drive for a cylinder having such a dedicated drive. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The invention is described below in greater detail by an embodiment of the invention, with reference being had to the drawing, wherein: 
     FIG. 1 is a schematic representation of a printing press; 
     FIG. 2 is an arrangement of the drive wheel train; 
     FIG. 3 is a printing form cylinder; 
     FIG. 4 is an arrangement of an eccentric version of the drive wheel train; 
     FIG. 5 is an eccentric version of the printing form cylinder; and 
     FIG. 6 is a partial drive scheme of a printing press. 
     FIG. 7 is a view similar to FIG. 6 showing a motor and pinion drive. 
    
    
     DETAILED DESCRIPTION 
     A four color printing press is shown in FIG.  1 . The press has an impression cylinder  1  with three printing areas  2 , respectively designated as  2 . 1 ,  2 . 2 , and  2 . 3 , and with three gripper rows  3 , respectively designated as  3 . 1 ,  3 . 2 , and  3 . 3 . A sheet feeding unit having a front edge sheet separator  4  and a gripper system  6  for transporting one sheet at a time to be printed from a feeder pile  5  to the impression cylinder  1  precedes the impression cylinder  1 . Sheet feeding to the impression cylinder  1  is arranged so that only every second gripper row  3  of the impression cylinder  1  receives a sheet. A delivery chain system  7  is allocated to the impression cylinder for sheet delivery. It takes the printed sheet from the impression cylinder  1  and transports it to a delivery pile  8 . Also in this case only every second gripper row of the impression cylinder  1  delivers a sheet. 
     Two cylinder groups  11 ,  18  are allocated to the impression cylinder  1 . Each cylinder group has one blanket cylinder  9  with two operating surfaces in operating connection with the impression cylinder  1  and a printing form cylinder  10  with two operating surfaces in operating connection to the blanket cylinder. The cylinders, i.e. impression cylinder  1 , blanket cylinder  9  and printing form cylinder  10 , are shown in their proper operating phase positions, in which the contact points of the corresponding opposite cylinders the operating surfaces facing each other with the front line of printing  29 . In this operating phase position the drive wheel train connects the cylinders with each other. The front lines of printing  29  of the cylinders, i.e. impression cylinder  1  and blanket cylinder  9  of the second cylinder group  18  are facing each other as shown in FIG.  1 . 
     An inking unit  19  is assigned to each operating surface of each printing form cylinder  10 . The inking unit  19  contains a form roller  20 . The inking unit  19  in the embodiment shown in FIG. 1 is configured as an Anilox inking unit. The Anilox inking unit contains besides the form roller  20  an ink metering roller  23  and a doctor blade system  24  therefor. 
     The printing press shown in FIG. 1 is equipped with two cylinder groups  11 ,  18 , with two blanket cylinders each with two operating surfaces, two printing form cylinders each with two operating surfaces, and four inking units, and therefore can operate as a four-color-press. 
     A printing press equipped with two blanket cylinders each having one operating surface, two printing form cylinders each having one operating surface, and two inking units, can operate as a two-color-press. 
     A printing press equipped with only one blanket cylinder and one printing form cylinder can operate as a one-color- or a two-color-press. 
     FIG. 2 shows the drive wheel train of a four-color-version of a printing press, with two cylinder groups. The drive wheel train has a motor  12  with a motor pinion  13 , an intermediate wheel  14 , an impression cylinder drive wheel  15 , two blanket cylinder drive wheels  17 , two printing form cylinder drive wheels  21 , four form roller drive wheels  22  and four ink metering roller drive wheels  25 . An dedicated drive  26  is allocated to each printing form cylinder. 
     The allocation of the dedicated drive  26  and the arrangement of the printing form cylinder drive wheel  21  at the printing form cylinder  10  are shown in FIG.  3 . The printing form cylinder  10  is connected with the printing form cylinder drive wheel  21  through a phase position clutch  27 . The printing form cylinder drive wheel  21  is part of the gear train of the printing press and is meshing with the blanket cylinder drive wheel  17  and with the form roller drive wheel  22 . The printing form cylinder  10  is suitably connected from its dedicated drive  26  through a metal bellows clutch  28 . The dedicated drive  26  is suitably an electric motor. 
     The method of the present invention is performed in a printing press with a cylinder group  11  or  18  by detaching of the driving connection (in operating phase position) between the printing form cylinder  10  and printing form cylinder drive wheel  21  thus to disengage the printing form cylinder  10  from the drive wheel train thus during image formation to drive the printing form cylinder  10  through its dedicated drive  26 . During image formation the rotational speed of the printing form cylinder  10 , i.e. the imaging speed, is much higher than the maximum printing speed and is suitably 2.5 times as high as the maximum printing speed. As a result of this, the time for image formation is reduced to a minimum and no load is applied to the other parts of the press, because the printing press stands still. 
     After image formation and shutting down the dedicated drive  26  the printing form cylinder  10  is again attached in its operating phase position to the drive wheel train with the phase position clutch  27 . As already mentioned above, the operating phase position is defined by facing of the front lines of printing  29  of the opposite cylinders which are in operating connection. The possibility of printing operation is now resumed. 
     In another embodiment of the drive of the present invention the dedicated drive  26  is supplied with a current to brake the printing press and to tension the drive wheel train. Thus the existing dedicated drive  26  can also be used to guarantee a pre-tensioning of the drive wheel train during the printing process. The current supplied to the dedicated drive  26  is suitably in the range of 10% of the current used by the main drive motor  12 . The current consumption of the main drive motor  12  fluctuates during the printing process and the dedicated drive  26  is supplied with a current to accommodate these fluctuations. 
     Alternatively, it is possible to attach and detach the printing form cylinder  10  from the drive system of the printing press with the printing form cylinder drive wheel  21  fixed to the printing form cylinder  10 , and the printing form cylinder  10  arranged in eccentric bearings  30 , as shown in FIGS. 4 and 5. The drive connection between the printing form cylinder drive wheel  21  and the drive wheel train will then be disengaged by rotating the eccentric bearing  30 , so that the printing form cylinder  10  is detached from the drive wheel train and can be driven by its dedicated drive  26  during image formation. The printing form cylinder  10  is engaged in its operating phase position to drive wheel train after image formation and shutting down the dedicated drive  26  by rotating the eccentric bearings  30 . The operating phase position is defined by facing of the front lines of printing  29  of the opposite cylinders which are in operating connection. Resumption of the printing operation is now possible. 
     In the method of the present invention for a printing press with two cylinder groups the drive connections (in the operating phase positions) between the printing form cylinders  10  and the printing form cylinder drive wheels  21  are disengaged by phase position clutches  27  and then the printing form cylinders  10  are detached from the drive wheel train. The printing form cylinders  10  are now driven at imaging speed by their respective dedicated drive  26 . 
     The printing form cylinders  10  are brought from the particular operating phase positions to a phase synchronous position relative to the imaging devices  16  in the catch-up operation during the run-up period of the dedicated drive  26  from standstill to the imaging speed. The phase synchronous position of the printing form cylinder  10  relative to the imaging devices  16  is suitably identical with the front line of printing  29 , i.e. both printing form cylinders  10  are facing with their front lines of printing the corresponding imaging device  16 . After this synchronization, the printing form cylinders  10  are driven synchronously with imaging speed. 
     The printing form cylinders  10  are brought back into their particular operating phase positions after the image formation by the following procedure. If the particular printing form cylinder  10  overshoots the operating phase position by the dedicated drive  26 , i.e. the dedicated drive  26  is stopped after passing the operating phase position. After that the printing form cylinder  10  is attached to the drive wheel train and mechanical means (phase position clutch) realizes the exact start in the operating phase position during start-up. 
     In another variant the operating phase position is obtained, with the following process steps. The dedicated drive  26  of the printing form cylinder  10  is stopped before reaching the operating phase position, then the printing form cylinder  10  is attached to the drive wheel train and mechanical means (phase position clutch) is used to realize the exact start in the operating phase position during start-up. 
     In another embodiment of the drive, after that the dedicated drive is supplied in the described manner by a braking current for the printing press and to tension the drive wheel train. 
     In a further embodiment of the invention the dedicated drive arranged at the printing form cylinder is used partially or totally to drive the printing press during the printing operation. This last embodiment is shown in FIGS. 6 and 7, and is next described by the example of a four-color printing press with two cylinder groups. 
     As already explained both printing form cylinders  10  with the printing form cylinder drive wheels  21  each have an dedicated drive  26 . The drive wheel train of the printing press contains in addition to the printing form cylinder drive wheels  21  two blanket cylinder drive wheels  17 , an impression cylinder drive wheel, two form roller drive wheels  22 , one gripper system drive wheel  31 , one front edge sheet separator drive wheel  32 , one intermediate delivery drive wheel  33  and one delivery chain drive wheel  34 . The printing form cylinder drive wheels  21  are not actively attached to the drive wheel train during the image formation and the dedicated drive  26  is only driving the printing form cylinders  10 . The printing press is at standstill and is not driven. 
     The inactive engagement of the printing form cylinder drive wheels  21  in the drive wheel train is possible as already explained either by separation of the particular printing form cylinder drive wheels  21  from the printing form cylinder  10  through a clutch or by disengagement of the printing form cylinder drive wheel  21  fixed mounted to the printing form cylinder  10  by swiveling the eccentrically mounted printing form cylinder including the printing form cylinder drive wheel  21 . The printing form cylinder drive wheels  21  of this embodiment of the invention are actively attached to the drive wheel train during printing operation and at least one dedicated drive  26  drives the printing press partially or totally. 
     Dedicated drives must be synchronized if more than one dedicated drives are used to drive the printing press. 
     In the case of a partial drive of the printing press by a dedicated drive  26  as shown in FIG. 7, only the functional groups with uniform rotating speed are driven by its drive wheels, such as the impression cylinder drive wheel  15 , the blanket cylinder drive wheels  17 , the printing form cylinder drive wheels  21  and the form roller drive wheels  22 . 
     The nonuniform rotation speed of the gripper system  6 , front edge sheet separator  4  and the delivery chain system  7  are driven by the gripper system drive wheel  31 , first intermediate wheel  35 , second intermediate wheel  36 , third intermediate wheel  37 , intermediate delivery drive wheel  33  and delivery chain drive wheel  34  from the motor  12 . This embodiment is advantageous, because drives that cause vibrations have their own drive gear train. 
     The motor  12  is synchronized with the dedicated drive or the dedicated drives. Another allocation of the driven functional groups to the motor and the dedicated drive respectively dedicated drives is also possible. 
     In the method of the present invention for a printing press with one cylinder group the drive connection (in the operating phase position) between the printing form cylinder and the drive wheel train is separated to detach the printing form cylinder from the drive wheel train and to drive the printing form cylinder with the dedicated drive  26  during image formation.