Abstract:
A printing machine with a cylinder sleeve ( 16 ), which can be rotationally driven and is supported at both ends with protruding axle journals ( 18 ) directly in the machine frame ( 10, 12 ), and with a shaft ( 22 ), which passes through the cylinder sleeve and can be driven along with it, such that the rotational driving takes place over the shaft ( 22 ) and the cylinder sleeve ( 16 ) can be set axially against a torque transfer element ( 28 ), which is seated on the shaft.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a printing machine with a cylinder sleeve, which can be rotationally driven and is supported at both ends with protruding axle journals directly in the machine frame, and with a shaft, which passes through the cylinder sleeve and can be driven along with it. 
     A printing machine of this type is disclosed by the EP-A-0 769 373. For this printing machine, the shaft is clamped boom-like in the machine frame, so that, for exchanging printing cylinders, the cylinder sleeve can be pulled off axially from the free end of the shaft, after the bearings for the cylinder sleeve are opened and the unit of shaft and cylinder sleeve has been lifted out of the bearings. The printing cylinder sleeve is driven over a gearwheel, which meshes with a driving gearwheel and is disposed on an extension of the axle journal of the cylinder sleeve. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a printing machine of the type named above, which permits the cylinder sleeve, especially the printing cylinder sleeve, to be exchanged easily and with which the printing cylinder sleeve can be driven directly by means of a driving motor disposed coaxially to it. 
     Pursuant to the invention, this objective is accomplished owing to the fact that the rotational driving is accomplished over the shaft and the cylinder sleeve can be set axially against a torque transfer element, which is seated on the shaft. 
     The shaft thus functions not only for supporting the cylinder sleeve during the exchange of cylinders, but also, at the same time, as a driving shaft. Accordingly, it is possible to couple the motor to the driving shaft, without interposing a gear drive. When cylinders are exchanged, the driving connection between the motor and the shaft need not be interrupted. Since the driving torque is transferred from the shaft to the cylinder sleeve simply by axially setting the cylinder sleeve against the torque transfer element, no special measures are required when exchanging cylinders in order to interrupt and restore the driving connection between the shaft and the cylinder sleeve. When the cylinder sleeve is pulled off from the shaft, the driving connection is interrupted automatically and, when the cylinder sleeve once again is pushed axially onto the shaft and reaches its end position on the shaft, it is set once again against the torque transfer element, so that the driving torque can be transferred once more to the cylinder sleeve. 
     The invention is not limited to the driving mechanism for the printing cylinder sleeve and can be used generally for exchangeable and rotationally driven rotating objects of a printing machine, for example, also for engraved ink transfer rollers and screen rollers of a flexographic printing press and the like. 
     The direct mounting of the cylinder sleeve in the machine frame has the advantage that the axis of rotation of the cylinder sleeve is defined precisely. Accordingly, it can be achieved that the printing machine runs quietly and the printing quality is perfect. Since, however, pursuant to the invention, the cylinder sleeve is driven over the shaft, which in turn must be supported in the machine frame, it is advisable to configure the support of the shaft and/or of the coupling between the shaft and the cylinder sleeve in such a manner, that redundancies of the axis of rotation are avoided and, accordingly, the axis of rotation of the cylinder sleeve continues to be determined primarily by the mounting of the axle journals in the machine frame. This can be achieved, for example, by mounting the shaft flexibly in the radial direction in the machine frame. If the shaft is coupled rigidly with the rotor of the driving motor, then this means that the rotor of the driving motor or the whole of the driving motor is also held flexibly in the radial direction at the machine frame. This can be achieved, for example, by a construction of the holding mechanism for the motor, which has a certain elasticity in the radial direction of the shaft. The torque transfer element between the shaft and the printing cylinder sleeve can then be constructed, for example, as a cone, which engages a counter-cone at the cylinder sleeve frictionally. When the cylinder sleeve is set axially against the cone, the shaft is centered in this manner on the axis of rotation defined by the axle journal of the cylinder sleeve. 
     In a different embodiment, the torque transfer element is constructed as a flat friction disk, which interacts with an end face of an axle journal of the cylinder sleeve. A friction coupling, so designed, offers the possibility of compensating for a slight eccentricity in the shaft in relation to the axis of rotation of the cylinder sleeve. In this case, the shaft can therefore also be mounted rigidly in relation to the machine frame. 
     The two solutions, which are described above and for which the cylinder sleeve is clamped with a relatively high force axially against the torque transfer element, so that a frictional transfer of torque is achieved, at the same time have the advantage that an axially fixed connection is created between the cylinder sleeve and the shaft. By these means, the advantageous possibility opens up of also adjusting the lateral register by way of the shaft. If the shaft is driven directly, it is, however, also necessary to ensure that, in this case, an axial adjustment of the shaft is possible while the driving connection between the shaft and the motor is maintained. This can be achieved, for example, owing to the fact that the rotor of the motor can be adjusted axially relative to the stator. The rotor can then be coupled rigidly with the shaft or constructed in one piece with the latter and participates in the axial movement of the shaft when the lateral register is adjusted. A further possibility consists of providing an axial coupling between the rotor of the motor and the shaft. In this case, during the adjustment of the lateral register, only the shaft is adjusted in the axial direction, whereas the rotor retains its axial position and the relative movement between the shaft and the rotor is compensated for by the axial coupling. Finally, it is also possible to support the whole of the motor housing so that it can be moved axially at the machine frame so that, when the lateral register is adjusted, the cylinder sleeve, the shaft and the motor are moved as a unit. 
     With respect to a simple and accurate adjustment of the longitudinal register, it is desirable that the cylinder sleeve can be coupled in a defined angular position with the shaft, so that the respective shaft angular position of the cylinder sleeve can be determined automatically with the help of an angular increment pick-up, which is disposed on the shaft or can be attached to the motor or integrated in the motor. For this purpose and, in accordance with a further development of the invention, at least one engaging dog is disposed at the torque transfer element or at the corresponding counter-surface at the cylinder sleeve and falls into a corresponding contour of the respectively other component, when the cylinder sleeve is set axially against the torque transfer element. In the peripheral direction, the engaging dog should engage the counter-contour without clearance, so that the angular position of the cylinder sleeve can be determined precisely. If the torque transfer element is constructed as a flat friction disk, the engaging dog and the counter-contour should, however, be movable in the radial direction relative to one another, so that it remains possible to compensate for the eccentricity between the shaft and the cylinder sleeve. Admittedly, owing to the fact that the engaging dog engages the counter-contour, there is a certain positive locking between the torque transfer element and the cylinder sleeve. However, the cylinder sleeve is clamped so tightly against the torque transfer element, that the torque transfer nevertheless primarily takes place by friction. Therefore, during the operation of the printing machine, the mechanical stress on the engaging dog is slight, so that wear and plastic or elastic deformation of the engaging dog is minimized. In this way, high precision can be achieved even in the long term when determining the angular position of the cylinder sleeve. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following, examples of the invention are described in greater detail by means of the drawing, in which 
     FIG. 1 shows a diagrammatic axial section through a cylinder sleeve of a printing machine with an associated driving mechanism and a lateral register adjustment device, 
     FIG. 1A shows an enlargement of a detail of FIG. 1, 
     FIG. 2 shows a representation corresponding to FIG. 1 with, however, an intermediate stage during the exchange of the cylinder sleeve and 
     FIG. 3 shows a driving mechanism and lateral register adjustment device of a modified embodiment. 
    
    
     DETAILED DESCRIPTION 
     In FIG. 1, the frame of a printing machine, for example, a flexographic printing machine, is represented by two side parts  10  and  12 , which are shown in section. A driving mechanism housing  14 , which is shown only diagrammatically, is mounted on the side part  10 . An exchangeable cylinder sleeve  16 , for example, a printing cylinder sleeve, is mounted with axle journals  18 , provided at each end, in the side parts  10  and  12 . In the case of the side part  12 , the bearing  20  for the cylinder sleeve  16  is removable. For example, this bearing  20  can be pulled axially from the axle journal  18  or the bearing is constructed as a tilting bearing with a bearing cover, which opens laterally, and can be moved on the side part  12  in the direction perpendicular to the plane of the drawing of FIG. 1, as described in EP-A-0 812 681. 
     In the gear housing  14 , a shaft  22  is mounted, which extends coaxially through the cylinder sleeve  16  and is connected over an axial coupling  24  with the output shaft of a motor  26 , rigidly held at the driving mechanism housing  14 . A torque transfer element, in the form of flat friction disk  28 , is seated rigidly on the shaft  22  and connected frictionally with the end face of the axle journal  18  of the cylinder sleeve  16 , so that the driving torque of the motor  26  is transferred to the cylinder sleeve  16 . At the free end, at the right in FIG. 1, the shaft  22  carries a clamping element  30 , which engages the axle journal  18  there and presses the cylinder sleeve  16  firmly against the friction disk  28 . 
     In the driving mechanism housing  14 , a known adjusting mechanism  32  for adjusting the lateral register is installed. This adjusting mechanism  32  is actuated by a servo motor  34  and permits the unit, formed by the shaft  22 , the cylinder sleeve  16  and the clamping element  30 , to be adjusted axially. The relative movement between the shaft  22  and the output shaft of the motor  26  is compensated for by the axial coupling  24 . 
     The motor  26  has an angle sensor  36 , which supplies a signal, which is representative of the angular position of the shaft  22  and is required for adjusting the longitudinal register. So that the signal of the angle sensor  36  is also representative of the angular position of the cylinder sleeve  16 , the angular position of the cylinder sleeve  16  relative to the shaft  22  is fixed by an engaging dog  38 , which is disposed at the outer periphery of the friction disk  28  and, in the form of a single tooth coupling, engages a corresponding recess  40  in the axle journal  18 , as shown on an enlarged scale in FIG.  1 A. The engaging dog  28  engages the recess  40  in the circumferential direction without clearance; however, in the axial direction, there is some clearance, so that slight, installation-required eccentricities between the shaft  22  and the cylinder sleeve  16  can be compensated for without the development of bending stresses in the shaft or the cylinder sleeve. In this way, it is ensured that the axis of rotation of the cylinder sleeve  16  is defined precisely by the mounting in the side parts  10  and  12 , independently of any inaccuracies during the installation of the driving mechanism housing  14 . 
     FIG. 2 illustrates the procedure when exchanging the cylinder sleeve  16 . It can be seen in FIG. 2 that the bearing  20  is removed on the side of the side part  12 . In addition, the clamping element  30  is loosened. In the examples shown, the clamping element  30  is a component with expandable elements which, in the loosened state, lie tightly against the periphery of the shaft  22 , so that the cylinder sleeve  16  can be pulled off over the clamping element axially from the shaft  22 . The construction of the clamping element is described in detail in the older European patent application 98 110 132. 
     The new cylinder sleeve  16  is pushed once again over the clamping element  30  onto the shaft  22  until it comes into contact with the end side of its axle journal  18  at the friction disk  28 . Moreover, the cylinder sleeve is aligned so that the engaging dog  38  can enter the recess  40 . Due to the arrow-shaped sloping of the engaging dog, automatic precise adjustment of the angular position of the cylinder sleeve  16  in relation to the shaft  22  is attained. Subsequently, the clamping element  30  is expanded once again and clamped against the cylinder sleeve  16 , so that the latter is pressed firmly against the friction disk  28 . Finally, the bearing  20  is installed once again and, with that, the process of exchanging cylinders is concluded. 
     FIG. 3 shows a modified embodiment, for which the axial coupling  24  is omitted and the output shaft of the motor  26  is connected rigidly with the shaft  22  or is formed in one piece with the latter. The housing of the motor  26  and of the angle sensor  36  is held axially displaceable in this case, but non-rotatably on a bracket  42  of the driving mechanism housing and, during the adjustment of the lateral register, participates in the axial movement of the shaft  22  and the cylinder sleeve  16 .