Abstract:
A method of operating a sheet-fed rotary printing machine includes mounting at least one rotating cylinder to be coupled to a drive or fixed relative to a framework, and moving an actuator to both uncouple the cylinder from the drive and fix the cylinder relative to the framework. A sheet-fed rotary printing machine includes a framework, a drive, at least one cylinder rotatably mounted to the framework, the cylinder is to be coupled to the drive or fixed relative to the framework, and a fixing and coupling configuration connected to the cylinder to both uncouple the cylinder from the drive and fix the cylinder relative to the framework.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates to a method of operating a sheet-fed rotary printing machine and to a sheet-fed rotary printing machine having a framework by which at least one cylinder is mounted in a rotatable manner. It is possible for the cylinder to be coupled to a drive or fixed relative to the framework.  
           [0003]    Such a method and such a sheet-fed rotary printing machine are disclosed in European Patent Application EP 0 878 301, corresponding to U.S. Pat. No. 6,308,620 A2 B1 to Wadlinger et al. The cylinder is, for example, a varnishing cylinder of a varnishing unit. During operation of the sheet-fed rotary printing machine, the cylinder interacts with an impression cylinder to print a printing-material sheet that is guided through between the cylinder and impression cylinder.  
           [0004]    During printing operation of multi-color sheet-fed printing machines, which may have a varnishing unit disposed downstream of them, the transported sheets are only printed with ink in the first printing units. Subsequent printing units or varnishing units idle along therewith. The corresponding impression cylinders are spaced apart from the associated varnishing cylinder. The configuration produces, between the cylinder and impression cylinder, a small gap through which the previously printed sheets are transported. The high machine speed causes the sheets to lift off from an impression cylinder and strike against the associated cylinder.  
           [0005]    In order to make possible smear-free sheet travel with printing, varnishing or finishing units switched off, Wadlinger proposes the formation, on or in the cylinder, of a sheet-directing configuration by which a sheet that is transported past the associated cylinder by the respective impression cylinder is kept away from the cylinder. The sheet-directing configuration is accommodated, for example, in a channel that runs axially in the lateral surface of the cylinder. A blowing tube that is connected to a blowing-air connection on the cylinder end side forms, for example, the sheet-directing configuration. The blowing air passing out of the blowing tube serves for forcing away from the cylinder, in the direction of the associated impression cylinder, a sheet that is transported through between the cylinder and the impression cylinder.  
           [0006]    To ensure satisfactory functioning of the sheet-directing configuration, it is necessary for the cylinder to be uncoupled from the associated drive and fixed in a specific angular position relative to the framework. According to Wadlinger, the cylinder is uncoupled from the drive by a coupling and fixed relative to the machine framework by a catch.  
         SUMMARY OF THE INVENTION  
         [0007]    It is accordingly an object of the invention to provide a method of operating a sheet-fed rotary printing machine having a framework by which at least one cylinder is rotatably mounted and sheet-fed rotary printing machine for implementing the method that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and that make it possible for the cylinder to be straightforwardly uncoupled from the drive and/or fixed relative to the framework. Another objective is for the method to be cost-effective to implement and for the sheet-fed rotary printing machine according to the invention to be cost-effective to produce.  
           [0008]    With the foregoing and other objects in view, there is provided, in accordance with the invention, a method of operating a sheet-fed rotary printing machine, including the steps of mounting at least one rotating cylinder to be selectively coupled to a drive and fixed relative to a framework and moving an actuator to both uncouple the cylinder from the drive and fix the cylinder relative to the framework.  
           [0009]    Simply by movement of an actuating element or actuating member, the cylinder is both uncoupled from the drive and fixed relative to the framework and vice-versa. The method and configuration give the advantage that, following the uncoupling operation, the cylinder is automatically and reliably fixed relative to the framework. Instead of a coupling and a catch, all that is required is for a single actuating element to be moved.  
           [0010]    In accordance with another mode of the invention, the cylinder is made to rotate in the circumferential direction by the movement of the actuating element, in particular, displacement of the actuating element parallel to the longitudinal axis of the cylinder. The specific rotation of the cylinder through a few degrees serves for adjusting the circumferential register. It is particularly practical if the movement of a single actuating element is used for coupling and fixing purposes and for adjusting the circumferential register. Preferably, the actuator is an actuating element or an actuating member.  
           [0011]    With the objects of the invention in view, there is also provided a sheet-fed rotary printing machine, including a framework, a drive, at least one cylinder rotatably mounted to the framework, the cylinder to be coupled to the drive or fixed relative to the framework, and a fixing and coupling configuration connected to the cylinder to both uncouple the cylinder from the drive and fix the cylinder relative to the framework. The fixing and coupling configuration both uncoupled the cylinder from the drive and fixes it relative to the framework and vice-versa. Prior to uncoupling from the drive, the cylinder is stopped in a defined angle position by Be the drive itself. The combined fixing and coupling configuration allows reliable uncoupling and fixing of the cylinder in a straightforward manner.  
           [0012]    In accordance with a further feature of the invention, the fixing and coupling configuration includes an actuating element that can be displaced parallel to the longitudinal axis of the cylinder. The axial displacement of the actuating element serves for uncoupling and fixing the cylinder and for adjusting the circumferential register.  
           [0013]    In accordance with an added feature of the invention, there is provided an actuating gearwheel that is fixed axially, and mounted rotatably, on the actuating element, coaxially with the cylinder, and engages with a driving gearwheel. Through the actuating gearwheel, the driving torque of the driving gearwheel is transmitted to the cylinder either directly or through the actuating element. The rotatable mounting ensures that the actuating gearwheel runs along with the driving gearwheel when the cylinder is fixed relative to the framework and that the driving gearwheel rotates.  
           [0014]    In accordance with an additional feature of the invention, the actuating element or an actuating member that can be moved relative thereto can be displaced axially between a coupling position, in which the cylinder is coupled to the drive, and a fixing position, in which the cylinder is fixed relative to the framework. The axial displacement of the actuating element or of the actuating member takes place directly or indirectly by an actuating motor.  
           [0015]    In accordance with yet another feature of the invention, in the coupling position of the actuating element or of the actuating member, the actuating gearwheel is connected to the cylinder in a form-fitting manner, through a first form-fitting element, directly or indirectly through the actuating element. The form-fitting connection between the actuating gearwheel and the cylinder ensures that the cylinder is driven during printing operation. The form fit prevents the actuating gearwheel and the cylinder from rotating relative to one another, which could have an adverse effect on the circumferential register during operation.  
           [0016]    A further preferred exemplary embodiment of the sheet-fed rotary printing machine is characterized in that the first form-fitting element includes a bolt that is fitted on the actuating gearwheel and, in the coupling position of the actuating element, is at least partially accommodated in a bore that is provided at the end of a flange or of an arm that is provided on the cylinder. The bolt may be formed integrally with the actuating gearwheel. As a result of the above-described axial fixing of the actuating gearwheel on the actuating element, axial displacement of the actuating element is transmitted to the bolt.  
           [0017]    In accordance with yet an added feature of the invention, the first form-fitting element includes a bolt that is prestressed by a spring, is fitted on the actuating element or the actuating member, and, in the coupling position of the actuating element or the actuating member, is at least partially accommodated in a bore that is provided in the actuating gearwheel. By virtue of the spring prestressing of the bolt, the cylinder remains coupled to the driving gearwheel even in the event of an auxiliary-power failure.  
           [0018]    In accordance with yet an additional feature of the invention, in the fixing position, the actuating element is connected to the framework through a second form-fitting element. The form-fitting connection between the cylinder and framework ensures that the cylinder is at a precise angle in the fixing position. The configuration makes it possible for a sheet-directing configuration disposed on or in the cylinder to be positioned precisely in relation to an associated impression cylinder.  
           [0019]    In accordance with again another feature of the invention, the second form-fitting element includes a bolt that is provided on the actuating element or the actuating member and, in the fixing position of the actuating element or of the actuating member, is at least partially accommodated in a bore that is provided on the framework. To ensure a clear angular relationship between the actuating gearwheel and the cylinder and/or between the cylinder and the framework, only one bolt or protrusion is provided in each case for the form-fitting connection between the actuating gearwheel and the cylinder and/or between the cylinder and the framework. It is also possible, however, for a plurality of bolts or protrusions to be disposed on concentric circles with different radii or for a plurality of bolts or protrusions to be disposed asymmetrically on one circle. Finally, it is also possible to use a plurality of bolts or protrusions that differ from one another in terms of size and shape. The bolts or protrusions and the associated bores or recesses are constructed to complement one another in each case to ensure a form fit between the respective parts.  
           [0020]    In accordance with again a further feature of the invention, the second form-fitting element is connected, in particular integrally, to the first form-fitting element and, in the fixing position of the actuating element or of the actuating member, is retained on the framework by a latching configuration. The latching configuration ensures that, despite the spring&#39;s prestressing of the first form-fitting element in the opposite direction, the second form-fitting element remains connected to the framework, to be precise, even in the event of an auxiliary-power failure.  
           [0021]    In accordance with again an added feature of the invention, there is provided an actuating member mounted on the actuating element. The actuating member is provided with a first and a second form-fitting element and can be moved between a coupling position, in which the cylinder is connected to the actuating gearwheel in a rotationally fixed manner through the first form-fitting element, and a fixing position, in which the cylinder is connected to the framework in a rotationally fixed manner through the second form-fitting element. The actuating member makes it possible for the cylinder to be uncoupled and fixed. A slight rotation of the cylinder for the purpose of adjusting the circumferential register may take place through a defined adjustment, in particular, a slight axial displacement, of the actuating element.  
           [0022]    In accordance with again an additional feature of the invention, the actuating member can be actuated by an actuating configuration and, in the non-actuated state, is retained in the coupling position or fixing position by at least one prestressed spring. As a result, the cylinder remains in its current state even in the event of an auxiliary-power failure.  
           [0023]    In accordance with still another feature of the invention, the actuating member is formed by a lever that is fitted pivotably on the actuating element and at one end of which the first and the second form-fitting elements are disposed on opposite sides with respect to one another. The configuration allows a quick switchover between the fixing and coupling positions.  
           [0024]    In accordance with still a further feature of the invention, the actuating member is formed by a slide that is guided in a displaceable manner relative to the actuating element. The dimensioning of the slide and of the complementary recesses in the cylinder, the actuating gearwheel, and the framework makes it possible to prevent the cylinder from rotating during the switchover between the fixing and coupling positions. For such a purpose, the slide has to be long enough for the cylinder briefly to be connected in a form-fitting manner both to the actuating gearwheel and to the framework.  
           [0025]    In accordance with still an added feature of the invention, the cylinder can be fixed relative to the framework by a further actuating element. The further actuating element serves for fixing the cylinder irrespective of the position of the first actuating element. In the exemplary embodiment, the first actuating element, thus, serves only for coupling the cylinder to the actuating gearwheel and for retaining the circumferential register.  
           [0026]    In accordance with still an additional feature of the invention, the further actuating element is formed by a slide that is guided on the framework and, for the purpose of fixing the cylinder, can engage at least partially in a recess that is formed on a flange or an arm of the cylinder. Instead of the slide, it is also possible to use a lever that is provided, at one end, with a form-fitting element that can engage in the recess formed on the cylinder.  
           [0027]    In accordance with another feature of the invention, the further actuating element is mounted such that it can he displaced radially and such that it is resilient tangentially to the cylinder. The resilient mounting in the direction transverse to the adjusting direction of the actuating element serves for compensating for positioning inaccuracies during the switchover operation.  
           [0028]    In accordance with a further feature of the invention, the fixing and coupling configuration includes a first additional actuating element, which serves for fixing the original actuating element relative to the framework, and a second additional actuating element, which serves for coupling the actuating element to the actuating gearwheel. The two additional actuating elements may be coupled to one another through a control configuration to ensure a disruption-free switchover between a fixing position and a coupling position of the cylinder. In the exemplary embodiment, the original actuating element serves for retaining the circumferential register.  
           [0029]    In accordance with an added feature of the invention, the first and the second additional actuating elements each include a form-fitting element, which can be accommodated in corresponding recesses in the original actuating element and the actuating gearwheel. The two form-fitting elements ensure that rotation of the cylinder and framework relative to one another in the fixing position and rotation of the cylinder and actuating gearwheel relative to one another in the coupling position are reliably prevented. To counteract relative rotation during the switchover operation, the two form-fitting elements may simultaneously engage with their complementary recess for a short period of time.  
           [0030]    In accordance with an additional feature of the invention, the actuating element is connected to the cylinder in a rotationally fixed manner through a form-fitting element, for example, a feather key or a toothing formation, in particular, a straight toothing formation. The configuration ensures, in particular, in the fixing position, that the cylinder is fixed in a defined angle position. At the same time, the rotatable mounting of the actuating gearwheel on the actuating element ensures that the actuating gearwheel, which engages with the driving gearwheel on a permanent basis, can rotate during operation.  
           [0031]    In accordance with yet another feature of the invention, the actuating gearwheel and the driving gearwheel are provided with an oblique toothing formation. Accordingly, axial displacement of the actuating element causes the cylinder, coupled to the actuating element in a rotationally fixed manner, to rotate in order for the circumferential register to be adjusted. The axial displacement of the actuating element and the rotation of the cylinder only take place to a small extent. The coupling between the actuating element and the cylinder may take place, for example, by a feather key or a straight toothing formation. The configuration ensures that the actuating element can be displaced axially relative to the cylinder.  
           [0032]    In accordance with yet a further feature of the invention, the actuating element is subjected to the action of a threaded bolt that, driven rotatably by a motor, is accommodated in a threaded bore that is provided in a flange that is connected to the framework in a rotationally fixed manner. Through the threaded bolt, the rotary movement of the motor is converted into a translatory movement of the flange, which is coupled to the actuating element. An axial bearing is preferably in provided between the flange and the actuating element to make it possible for the actuating element and the cylinder to rotate relative to the flange as far as possible without friction.  
           [0033]    In accordance with yet an added feature of the invention, the actuating element is prestressed by a spring. The spring prestressing holds the actuating element in abutment against the flange.  
           [0034]    In accordance with yet an additional feature of the invention, the threaded bolt has a self-locking thread. The self-locking ensures, in conjunction with the spring&#39;s prestressing, that the threaded bolt remains in its respective position in the event of an auxiliary-power failure. This means that an undesired coupling operation does not take place.  
           [0035]    In accordance with again another feature of the invention, there is provided a bevel formed on the bolt. The bevel serves for compensating for positioning inaccuracies during coupling and fixing of the cylinder. The form-fitting counterpart to the bolt is preferably provided with a complementary funnel-shaped widening.  
           [0036]    In accordance with a concomitant feature of the invention, the actuating gearwheel is braced in relation to the driving gearwheel by a clamping gearwheel. The configuration ensures play-free force transmission between the driving gearwheel and the cylinder during printing operation.  
           [0037]    Other features that are considered as characteristic for the invention are set forth in the appended claims.  
           [0038]    Although the invention is illustrated and described herein as embodied in a method of operating a sheet-fed rotary printing machine and sheet-fed rotary printing machine, it is, nevertheless, not intended to be limited to the details shown because 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.  
           [0039]    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 DRAWINGS  
       [0040]    [0040]FIG. 1 is a fragmentary, cross-sectional view of part of a multicolor sheet-fed rotary printing machine according to the invention;  
         [0041]    [0041]FIG. 2 is a fragmentary, cross-sectional view of a first embodiment of the sheet-fed rotary printing machine of FIG. 1,  
         [0042]    FIGS.  3  to  7  are enlarged, cross-sectional view of form-fitting elements of FIG. 2 in different switching states;  
         [0043]    [0043]FIG. 8 is a fragmentary, cross-sectional view of a second embodiment of the sheet-fed rotary printing machine of FIG. 1;  
         [0044]    [0044]FIG. 9 is an enlarged, fragmentary, cross-sectional view of a form-fitting element of the sheet-fed rotary printing machine of FIG. 8,  
         [0045]    [0045]FIG. 10 is a fragmentary, cross-sectional view of a third embodiment of the sheet-fed rotary printing machine of FIG. 1;  
         [0046]    [0046]FIG. 11 is a fragmentary, cross-sectional view of a fourth embodiment of the sheet-fed rotary printing machine of FIG. 1,  
         [0047]    [0047]FIG. 12 is a fragmentary, cross-sectional view of a fifth embodiment of the sheet-fed rotary printing machine of FIG. 1,  
         [0048]    [0048]FIG. 13 is an enlarged, fragmentary, cross-sectional view of form-fitting elements of the sheet-fed rotary printing machine of FIG. 11;  
         [0049]    [0049]FIG. 14 is an enlarged, fragmentary, cross-sectional view of form-fitting elements of the sheet-fed rotary printing machine of FIG. 12; and  
         [0050]    [0050]FIG. 15 is a fragmentary, cross-sectional view of a sixth embodiment of the sheet-fed rotary printing machine of FIG. 1. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0051]    Referring now to the figures of the drawings in detail and first, particularly to FIG. 1 thereof, there is shown part of a multi-color sheet-fed rotary printing machine. Sheets have already been printed by upstream non-illustrated printing units, and are fed to a printing unit  1  that has been switched off. From here, the printed sheets are transported, by transfer drums  2 , through a varnishing unit  3 , which is not involved in the printing operation either, and are then fed to a sheet-delivery device  4 . In the illustrated case, a printing-blanket cylinder  5  and a varnishing-blanket cylinder  6  have been withdrawn from an associated impression cylinder  7 ,  8 . The printing-blanket cylinder  5  and the varnishing-blanket cylinder  6  have cylinder channels  9 , in which blanket-tensioners are provided in a conventional manner.  
         [0052]    Provided in the cylinder channels  9  of the printing-blanket cylinder  5  and varnishing-blanket cylinder  6  are sheet-directing elements  10 , which may be constructed as directing plates and/or directing tongues. The directing plates and/or directing tongues  10  can be inserted into the cylinder channels  9  and fastened here. As a result, for example, during the operation of printing stiff cardboard, the trailing sheet edge can slide along the directing plates and/or directing tongues without the imprint being damaged.  
         [0053]    The sheet-directing elements  10  may also be configured as blowing tubes that can be coupled to blowing-air connections on the cylinder end side. The blowing tubes  10  can discharge a vertical air stream onto the sheets that are to be transported, and achieve the highest contact-pressure force as a result. The blowing air of the blowing tubes is directed perpendicularly onto the sheets transported by the respective impression cylinders  7 ,  8 , with the result that the sheets are forced down onto the respective impression cylinders  7 ,  8  without coming into contact with parts of the printing-blanket cylinder  5  or varnishing-blanket cylinder  6 . To ensure satisfactory functioning of the sheet-directing elements, the printing-blanket cylinder  5  and the varnishing-blanket cylinder  6  have to be positioned at a defined angle. The positioning can be achieved by securing the printing-blanket cylinder  5  and the varnishing-blanket cylinder  6  on a side wall of the sheet-fed rotary printing machine. The printing-blanket cylinder  5  and the varnishing-blanket cylinder  6  have to be uncoupled from their drive at the same time.  
         [0054]    [0054]FIG. 2 shows a. framework  11  with a mounting  12  for a cylinder  13 . The cylinder  13  is, for example, the printing-blanket cylinder  5  or varnishing-blanket cylinder  6  of the sheet-fed rotary printing machine illustrated in FIG. 1. The mounting  12  ensures that the cylinder  13  can rotate during operation. The rotary movement of the cylinder  13  is produced by a driving gearwheel  14  that can be coupled to the cylinder  13  through an actuating gearwheel  15 . The actuating gearwheel  15  is mounted rotatably on an actuating element  17  by a mounting  16 . The mounting  16  is formed by two radial ball bearings. The actuating gearwheel  15  is fixed axially on the actuating element  17  by a ring  18 , which is accommodated in a circumferential groove of the actuating element  17  and projects out of the groove.  
         [0055]    A bolt  20  is formed on the actuating gearwheel  15  and extends parallel to the longitudinal axis of the cylinder  13 . The bolt  20  is partially accommodated in a bore  21  that is provided at the end of an arm  22  such that it likewise runs parallel to the longitudinal axis of the cylinder  13 . The arm extends radially from the cylinder  13 . The bolt  20  accommodated in the bore  21  produces a form-fitting connection between the actuating gearwheel  15  and the cylinder  13 . A spring prestressing configuration  23  compensates for any possible play between the bolt  20  and the bore  21 . In order to realize play-free force transmission between the driving gearwheel  14  and the cylinder  13  during printing, the actuating gearwheel  15  is braced in relation to the driving gearwheel  14  by a clamping gearwheel  24 .  
         [0056]    In the region of the mounting  16 , the actuating element  17  is in the form of a circular-cylindrical sleeve that is connected to the cylinder  13  in a rotationally fixed manner through a feather key  25 . The feather key  25  makes it possible for the actuating element  17  to be displaced axially relative to the cylinder  13 .  
         [0057]    If the actuating element  17  is displaced axially (in relation to the cylinder  13 ) in the direction of the framework  11  from the position illustrated in FIG. 2, then the actuating gearwheel  15 , with the bolt  20 , is displaced to the same extent as a result of the axial fixing by the ring  18 . The bolt  20  is, thus, drawn out of the bore  21 . At the same time, a bolt  26 , which is formed on the actuating element  17  and runs parallel to the longitudinal axis of the cylinder  13 , moves toward a bore  27 , which is provided in the framework  11 . The dimensions of the bolts  20  and  26  and the spacings between the bolts  20 ,  26  and the bores  21 ,  27  are selected in each case such that the bolt  26  engages in the bore  27  before the it bolt  20  has moved out of the bore  21  to the full extent. As such, during displacement of the actuating element  17 , it is always ensured that at least one of the bolts  20 ,  26  is accommodated in the associated bore  21 ,  27 .  
         [0058]    The position of the actuating element  17  that is illustrated in FIG. 2, and in which the actuating gearwheel  15  is connected to the cylinder  13  in a form-fitting manner through the bolt  20  and the arm  22 , is referred to as the coupling position. A form-fitting or form-locking connection is one that connects two elements together due to the shape of the elements themselves, as opposed to a force-locking connection, which locks the elements together by force external to the elements. In the coupling position, the cylinder  13  is driven by the driving gearwheel  14 . The driving gearwheel  14  is coupled to the non-illustrated main drive of the sheet-fed rotary printing machine. The cylinder  13  can be stopped in a specific angle position through the main drive to give the correct positioning of a channel, disposed in the cylinder  13 , with a blowing-air tube. As long as the driving gearwheel  14  is at a standstill, the actuating element  17  can be displaced parallel to the longitudinal axis of the cylinder  13  until the bolt  26  is accommodated in the bore  27  on the framework  11 . In the so-called fixing position (which is not illustrated in FIG. 2), the actuating element  17  is connected to the framework  11  in a form-fitting manner. In the fixing position, the feather key  25  ensures that the cylinder  13  maintains its precisely defined angle position. At the same time, the mounting  16  ensures that the actuating gearwheel  15  can rotate relative to the actuating element  17 . In the fixing position, the bolt  20 , formed on the actuating gearwheel  15 , is no longer accommodated in the bore  21 , which is formed on the cylinder arm  22 . If the driving gearwheel  14 , then, is made to rotate again through the main drive, the actuating gearwheel  15  rotates along therewith without its movement being transmitted to the actuating element  17  or the cylinder  13 .  
         [0059]    The driving gearwheel  14  and the actuating gearwheel  15  also engage with one another throughout the operation of switching over between the coupling position and fixing position. The engagement has the advantage that any possible damage that could occur during the inter-engagement of the two gearwheels  14 ,  15  is avoided. The permanent engagement of the gearwheels  14 ,  15  maintains a constant rotary-angle relationship. As a result, it is possible for the cylinder  13  to be positioned precisely through the driving gearwheel  14 .  
         [0060]    An arm  28  extends radially inward from the actuating element  17 . On a side that is directed toward the cylinder  13 , the arm  28  is subjected to the action of a compressively prestressed spring  29 , the majority of which is disposed in the interior of the cylinder  13 . On a side of the arm  28  that is directed away from the cylinder  13 , a flange  30  is fixed to the framework  11 . Provided between the flange  30  and the arm  28  is an axial bearing  31 , which makes it possible for the actuating element  17  to be rotated relative to the flange  30 . The flange  30  is provided with a central bore  32  with a non-illustrated internal thread. The internal thread of the bore  32  interacts with the non-illustrated external thread of a bolt  33 , which can be made to rotate specifically by an actuating motor  34 . The end surface formed at the free end of the bolt  33  butts against the arm  28 .  
         [0061]    Rotation of the threaded bolt  33  results in axial displacement of the flange  30  relative to the threaded bolt  33 . The axial displacement of the flange  30  is transmitted to the actuating element  17 . The dimensions of the relevant components are selected such that further axial displacement of the actuating element  17  is possible to ensure that the bolt  26  can also engage in the bore  27  of the framework  11 . The arm  28  is in permanent abutment against the flange  30 , even during the axial displacement of the actuating element  17  in the direction of the framework  11 .  
         [0062]    The actuating element  17  makes it possible for the cylinder  13 , during uncoupling from the driving gearwheel  14 , to be simultaneously secured in a predetermined position on the framework  11 . Only an angular relationship is admissible between the driving gearwheel  14  and the cylinder  13 . During the switchover between the fixing position and the coupling position, the actuating element  17  is displaced in an axis-parallel manner to the cylinder  13  by the actuating motor  34 , through the threaded bolt  33 . Due to the mounting  16 , the actuating gearwheel  15  is moved along correspondingly.  
         [0063]    The bolt  20  engages with the cylinder  13  during printing operation. When the printing machine is at a standstill, displacement of the actuating element  17  releases the connection between the bolt  20  and the cylinder  13 , and the bolt  26  comes into engagement with the framework  11 . By virtue of the feather key  25 , the cylinder  13  is, thus, secured on the framework  11 . The actuating gearwheel  15  idles along during printing. The bolts  20  and  26  are disposed and dimensioned such that it is only possible to have an angular relationship between the actuating gearwheel  15  and the cylinder  13  and/or between the cylinder  13  and the framework  11 . The construction is achieved by using only one bolt  20 ,  26  in each case to provide a form-fitting connection between the actuating gearwheel  15  and the cylinder  13  and/or the cylinder  13  and the framework  11 . Alternatively, it is also possible to use a plurality of bolts that either are disposed a symmetrically on one and the same radius or are disposed on different radii. Furthermore, it is also possible to use a plurality of bolts that differ in terms of size and/or shape.  
         [0064]    The thread of the bolt  33  has a self-locking configuration. Due to the self-lock in the threaded bolt  33  and of the prestressing force of the spring  29 , it is ensured that the actuating element  17  remains in its current position even in the event of an auxiliary-power failure. An undesired coupling process, thus, does not take place.  
         [0065]    A bevel  35  is formed on the bolts  20  and  26  in each case. The bevel  35  makes it possible to compensate for positioning inaccuracies of the main drive during the switchover from the fixing position to the coupling position and vice-versa.  
         [0066]    The actuating gearwheel  15  is connected to the driving gearwheel  14  through a non-illustrated oblique toothing formation. When the driving gearwheel  14  is at a standstill, the oblique toothing formation, in the case of axial displacement of the actuating gearwheel  15 , results in the actuating gearwheel  15  rotating slightly. Such rotation is transmitted to the cylinder  13  through the bolt  20  and can be utilized to adjust the circumferential register.  
         [0067]    Sections A and B are marked on the bolt  20  and serve for rotating the cylinder  13  specifically through a few degrees. In the variant illustrated in FIG. 2, it is, thus, possible to use one and the same actuating element  17  both to adjust the circumferential register and to switch over between the fixing and coupling positions. The operations of switching over between the fixing and coupling positions and of retaining the circumferential register may be achieved by axial displacement of the actuating element  17  through just one actuating motor  34 .  
         [0068]    FIGS.  3  to  7  show the bolts  20  and  26  in different states during the switchover between the coupling position and the fixing position. In FIGS.  3  to  7 , it is indicated that a funnel-shaped widening  36  is provided on the bore  27 . In the same way, a funnel-shaped widening  37  is provided on the bore  21 . The funnel-shaped widenings  36  and  37  interact with the respective bevel  35  that is formed on the bolts  20  and  26 . By virtue of the interaction between the bevel  35  and the funnel-shaped widenings  36  and  37 , it is possible to compensate for tolerances and positioning inaccuracies of the main drive during the switchover operation. During the switchover operation, the position of the cylinder  13  is oriented either in relation to the actuating gearwheel  15 , which is positioned in a rotationally secured manner by the driving gearwheel  14  when the machine is at a standstill, or in relation to the framework  11 .  
         [0069]    In FIG. 3, the bolt  20  is accommodated more or less entirely in the bore  21 . Accordingly, the actuating gearwheel  15  engages with the cylinder  13 . In such a case, the sheet-fed rotary printing machine is printing.  
         [0070]    In FIG. 4, the sheet-fed rotary printing machine is at a standstill. The bolt  20  moves out of the bore  21  and the bolt  26  moves into the bore  27 . In such a state, the bolts  20  and  26  butt, by way of their bevel  35 , against the funnel-shaped widenings  36  and  37  of the associated bores. The action is achieved in that, in a position illustrated in FIG. 1, the cylinder  13 , rather than being in equilibrium, tries to rotate to one side due to an imbalance caused by a channel of the cylinder  13 .  
         [0071]    In the state illustrated in FIG. 5, the bolt  20  butts, by way of the bevel  35 , against the funnel-shaped widening  37  of the bore  21 . At the same time, the bolt  26  butts, by way of its bevel  35 , against the funnel-shaped widening  36  of the bore  27 .  
         [0072]    By virtue of the actuating element being displaced further in the direction of the framework, the bolt  26  moves further into the bore  27 . Accordingly, in such a state, which is illustrated in FIG. 6, the bolt  26  and the framework determine the position of the cylinder  13 .  
         [0073]    In FIG. 7, the actuating element  17  is located in its fixing position and the bolt  26  is accommodated entirely in the bore  27 . At the same time, the bolt  20  has moved out of the bore  21  to the full extent. During displacement of the actuating element  17  from the fixing position into the coupling position and vice-versa, the cylinder  13  executes a small rotary movement due to the imbalance, caused by the cylinder channel, in the circumferential direction and due to the sliding-wedge action of the bevels  35 .  
         [0074]    A second variant is illustrated in FIG. 8 and is similar to the first variant illustrated in FIG. 2. Accordingly, the same parts are provided with the same designations. Thus, for descriptions of like part, reference is made to the description of FIG. 2. only the differences between the two variants are discussed below.  
         [0075]    In the second variant of FIG. 8, the operations of uncoupling the actuating gearwheel  15  from the cylinder  13  and retaining the circumferential register are achieved by axial displacement of the actuating element  17 , as in the first variant (FIG. 2). In the second variant, however, there is no second form-fitting element fitted on the actuating element  17 . Instead, in the second variant, the cylinder  13  is fixed relative to the framework  11  by a further actuating element  41  in the form of a radially moveable slide.  
         [0076]    The further actuating element  41  is illustrated in FIG. 9 on an enlarged scale. Double arrows  42  and  43  indicate that the further actuating element  41  can be moved back and forth in the radial direction in relation to the cylinder  13 . A tip  44 , which is in the form of an isosceles trapezoid in cross-section, is formed on the further actuating element  41 . The tip  44  is accommodated in a recess  45  that is formed on the arm  22  of the cylinder  13 . In the state illustrated in FIG. 9, the further actuating element  41 , thus, engages with the arm  22  of the cylinder. As such, the cylinder is fixed on the framework. To compensate for any possible positioning inaccuracies of the main drive, the further actuating element  41  is mounted resiliently in the direction transverse to the adjusting direction  42 ,  43  by springs  46  and  47 .  
         [0077]    A third variant is illustrated in FIG. 10 and is similar to the first variant illustrated in FIG. 2. The same parts are provided with the same designations. Thus, reference is made to the description relating to FIG. 2 for such like parts. To avoid repetition, only the differences between the two variants are discussed below.  
         [0078]    In a third variant shown in FIG. 10 there is no form-fitting element fitted on either the actuating gearwheel  15  or the actuating element  17 . Instead, an actuating member  50  is guided on the actuating element  17  such that it can be displaced parallel to the longitudinal axis of the cylinder  13 . An actuating motor  51  displaces the actuating member  50 . Formed on the actuating member  50  is a bolt  52 , of which the longitudinal axis runs parallel to the longitudinal axis of the cylinder  13  and of which the tapering tip is accommodated in a bore  53  in the actuating gearwheel  15 . A compressively prestressed spring  54  ensures that the actuating member  50  remains in the position illustrated in FIG. 10 even in the event of an auxiliary-power failure.  
         [0079]    A bolt  55  is formed on the actuating member  50  on the side opposite to the bolt  52 . The bolt  55  likewise extends parallel to the longitudinal axis of the cylinder  13  and, during axial displacement of the actuating member  50  in the direction of the framework  11 , is accommodated in a bore  56  that is disposed in the framework  11 . On the framework  11 , moreover, a spring-prestressed catch  57  is guided such that it can be displaced perpendicularly to the longitudinal axis of the cylinder  13 . The catch  57  can engage in a recess  58  in the bolt  55 . Such a configuration ensures that, in the fixing position, the bolt  55  is retained in the bore  56  counter to the prestressing force of the spring  54 . In a fixing position (which is not illustrated in FIG. 10), a straight toothing formation  59  provides a rotationally fixed connection between the actuating element  17  and the cylinder  13 . The straight toothing formation  59 , like the feather key  25  in the preceding variants, ensures axial displacement of the actuating element  17  on the cylinder  13 .  
         [0080]    In the third variant of FIG. 10, it is only the adjustment of the circumferential register that takes place by axial displacement of the actuating element  17 . Axial displacement of the actuating member  50  performs the operation of switching over between the coupling and fixing positions. Accordingly, the actuating gearwheel  15  does not move during the switchover between the fixing and coupling positions. During a printing operation, which is illustrated in FIG. 10, the bolt  52  engages with the actuating gearwheel  15 . The form-fitting connection is prestressed by the spring  54 . Upon disengagement, the actuating member  50  is displaced axially, counter to the prestressing force of the spring  54 , by the actuating motor  51  or a pneumatic cylinder until the bolt  55  engages in the framework  11  and the catch  57  latches into the recess  58 . For re-coupling purposes, the catch  57  has to be released. The catch  57  may be replaced by a self-locking actuating element, such as an eccentric or a toggle lever.  
         [0081]    The functioning of the circumferential register is achieved by axial displacement of the actuating element  17  in the third variant (FIG. 10) with the driving gearwheel  14  at a standstill.  
         [0082]    In the event of an auxiliary-power failure, the bolt  52  remains in engagement with the actuating gearwheel  15  during printing operation due to the prestressing force of the spring  54 . In a disengaged state, the actuating member  50  is secured by the catch  57  against undesired interengagement of the bolt  52  and the actuating gearwheel  15 .  
         [0083]    Fourth and fifth variants of the invention are illustrated in FIGS. 11 and 12 and are similar to the first variant, which is illustrated in FIG. 2. The same parts are provided with the same designations. Thus, reference is made to the description of FIG. 2 for such parts. To avoid repetition, only the differences between the individual variants are discussed below.  
         [0084]    In the fourth variant, illustrated in FIG. 11, an actuating member  61  is mounted pivotably on the actuating element  17 . A first form-fitting element  62  and a second form-fitting element  63  are formed on the actuating member  61 . The first form-fitting element  62  can engage in a recess  64  that is provided in the framework  11 . The second form-fitting element  63  can engage simultaneously in a recess  65 , which is made in the actuating element  17 , and in a recess  66 , which is formed in the actuating gearwheel  15 .  
         [0085]    [0085]FIG. 13 is an enlarged, side view of the actuating member  61 . As can be seen, the actuating member  61  is formed by a spring-prestressed lever that is mounted, more or less in the center, pivotably on the actuating element  17 . At one end of the lever, a first form-fitting element  62  and a second form-fitting element  63  are formed on opposite sides with respect to one another. The first form-fitting element  62  can engage in a recess  64  that is provided on the framework  11 . The second form-fitting element  63  engages simultaneously in a recess  65 , which is made on the actuating element  17 , and in a recess  66 , which is made on the actuating gearwheel  15 . An actuating motor  67  or a pneumatic cylinder, which serves for actuating the actuating member  61 , is disposed at the other end of the lever arm.  
         [0086]    In the fourth variant of FIG. 11, the operation of switching over between the coupling and fixing positions is achieved by the actuating member  61 . During printing operation, the form-fitting element  63  engages in the recesses  65  and  66  and, thus, provides a form-fitting connection between the actuating element  17  and the actuating gearwheel  15 . A straight toothing formation  69  ensures a rotationally fixed connection between the actuating element  17  and the cylinder  13 . In a fixing position (not illustrated in FIGS. 11 and 13), the actuating member  61 , with the form-fitting element  62 , ensures that the actuating element  17  is fixed relative to the framework  11 . In the fixing position, the straight toothing formation  69  prevents a rotary movement of the cylinder  13 . If the actuating element  17  is displaced axially by the actuating motor  34 , through the threaded bolt  33 , it is possible for the cylinder  13 , as a result of the interaction of the oblique toothing formation between the driving gearwheel  14  and the actuating gearwheel  15  with the straight toothing formation  69  between the actuating element  17  and the cylinder  13 , to be rotated in a defined manner through a few degrees to retain the circumferential register.  
         [0087]    In the fifth variant illustrated in FIGS. 12 and 14, the operation of retaining the circumferential register takes place, in the same manner as with the variant illustrated in FIGS. 11 and 13, by the interaction of the oblique toothing formation between the driving gearwheel  14  and the actuating gearwheel  15  with a straight toothing formation  79  between the actuating element  17  and the cylinder  13 . In the fifth variant of FIG. 12, the operation of switching over between the coupling and fixing positions is achieved by an actuating member  71 , on which a first form-fitting element  72  and a second form-fitting element  73  are formed on opposite sides with respect to one another. The first form-fitting element  72  can engage in a recess  74  that is formed on the framework  11 . The second form-fitting element  73  engages simultaneously in a recess  75  in the actuating element  17  and in a recess  76  in the actuating gearwheel  15 , the configuration providing a form-fitting connection between the actuating gearwheel  15  and the actuating element  17 . The actuating member  71  can be moved back and forth in the radial direction, in relation to the cylinder  13 , by an actuating motor or a pneumatic cylinder  77 .  
         [0088]    [0088]FIG. 14 is an enlarged, side view of the actuating member  71 . As in FIG. 12, the actuating member  71  is located in a coupling position, in which the form-fitting element  73  ensures a form-fitting connection between the actuating gearwheel  15  and the actuating element  17 . The actuating member  71  is prestressed in the position by springs. In the event of an auxiliary-power failure, the actuating member  71  is retained in the position shown in FIGS. 12 and 14 due to the spring prestressing force. Such retention prevents undesired disengagement.  
         [0089]    The sixth variant illustrated in FIG. 15, is similar to the first variant illustrated in FIG. 2. Accordingly, the same parts are provided with the same designations. Thus, reference is made to the description relating to FIG. 2 for such parts. To avoid repetition, only the differences between the two variants are discussed below.  
         [0090]    In the sixth variant, the operation of retaining the circumferential register takes place in the same way as for the preceding variants, namely by axial displacement of the actuating element  17 . In the sixth variant of FIG. 15, the operation of switching over between the coupling and fixing positions takes place by adjustment of a first additional actuating element  81  and of a second additional actuating element  82 . A form-fitting element  83  is formed on the first additional actuating element  81 . The form-fitting element  83  engages in a recess  84  that is provided on the actuating element  17 . The second additional actuating element  82  has a form-fitting element  85 , which engages both in a recess  86  in the actuating element  17  and a recess  87  in the actuating gearwheel  15  to connect the latter to the actuating element  17  in a form-fitting manner.  
         [0091]    In all the variants, only a single angle position is admissible between the cylinder  13  and the driving gearwheel  14 . However, in the case of a half-revolution or third-revolution cylinder, two or three positions, respectively, are also, of course, conceivable. The same applies to the operation of fixing the cylinder  13  relative to the framework  11 . In the case of a half-revolution or third-revolution cylinder, two or three positions, respectively, are conceivable here as well.