Abstract:
The interval or spacing between rotational axes of adjacent cylinders in a rotary printing press, between a print-on position and a print-off position is accomplished using eccentric bushings for the cylinder journals of at least one of the cylinders. A printing gap between the two cylinders can also be varied using separate eccentric bushings. The effective eccentricity of the bushings extends parallel to a line connecting the axes of rotation of the cylinders.

Description:
FIELD OF THE INVENTION 
     The present invention is directed to an arrangement for setting the spacing between the axes of rotation of cylinders. The cylinders are cooperating cylinders of a rotary printing press and are each supported by eccentric bushings. 
     BACKGROUND OF THE INVENTION 
     Printing units are known from DE 42 11 379 A1. The ink application rollers of these printing units are each seated, on both sides, in two adjustable eccentric bushings . 
     EP 0 591 792 A1 discloses a rubber blanket cylinder of a printing press whose journal is seated in a first eccentric bushings for use in putting the cylinder into or out of the printing position. A second bushing is used for setting the paper thickness. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is directed to providing an arrangement for the selective setting of the spacing between two cylinders of a printing press. 
     In accordance with the present invention, the object is attained by the provision of first and second eccentric bushings that support a blanket cylinder for movement with respect to a counter-pressure cylinder. The first eccentric bushing, or bushings are used to move the blanket cylinder between printing and non-printing positions. The second eccentric bushing, or bushings are used to set a variable printing gap between the two cylinders. 
     The advantages which can be achieved by the present invention lie, in particular, in that by the use of a shaft journal seating in accordance with the present invention, it is possible, on the one hand, to move a cylinder, for example a rubber blanket cylinder, away from one or two adjoining cylinders of a printing unit. On the other hand, a separate, differentiated setting of a print gap toward an adjoining cylinder can be performed by simple technical elements without changing the print gap toward a second adjoining cylinder. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred embodiment of the present invention is represented in the drawings and will be described in greater detail in what follows. 
     Shown are in: 
     FIG. 1, a schematic side elevation view of a printing position of a cylinder, of an arrangement for placing a cylinder into a print-on and print-off position in accordance with the present invention, and in 
     FIG. 2, an enlarged depiction of the journal areas of a cylinder in accordance with FIG.  1  and with a paper thickness setting device. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A transfer cylinder  01 , for example a rubber blanket cylinder  01  of a printing unit of a rotary printing press, is depicted in the side elevation view of FIG. 1. A periphery  02  of cylinder  01  rests against the periphery of a forme cylinder  03 . The rubber blanket cylinder  01  can be placed against a counter-pressure cylinder  04 , for example a second rubber blanket cylinder  04 , and is represented in this position by solid lines, as seen in FIG. 1. A print gap  06  for the passage of, for example a paper web, for printing the paper web, which paper web is not specifically represented in FIG. 1, is formed between the two cylinders  01 ,  04 . 
     A first cylinder journal  07 , which may be, for example a shaft journal of the rubber blanket cylinder  01 , and which has a cylinder axis or an axis of rotation  08 , is seated in a first, inner eccentric cylinder bushing  09  which has a cylinder axis or an axis of rotation  11 . It is possible to obtain a first eccentricity “e” of, for example 12 mm, between the two axes of rotation  08 ,  11 . 
     The first eccentric cylinder bushing  09  is, in turn, rotatably seated in a second, outer eccentric cylinder bushing  12 , which has an axis of rotation  13 . The second, outer cylinder bushing  12  is seated, so it can be rotated, in a bore  14  of a lateral frame of the printing press, which lateral frame is not specifically represented in the drawings. By use of this second, outer eccentric cylinder bushing  12 , it is possible to obtain a second eccentricity “f” of 3 mm, for example, between the axis of rotation  11  of the first, inner cylinder bushing  09  and the axis of rotation  13  of the second, outer cylinder bushing  12 . It is possible to arrange rolling bearings, which are not specifically represented, in particular needle bearings, or cylinder roller bearings, between each of the cylinder journal  07 , the first cylinder bushing  09 , the second cylinder bushing  12 , as well as the lateral frame bore  14 . Any other type of rolling bearing or sliding bearing is also useable. 
     The ratio of the two eccentricities “e” to “f” lies in the range of 2 to 6, preferably in the range 3 to 5, and in particular in the range 3.5 to 4.5. 
     The first, inner cylinder bushing  09  can be pivoted, for example by the use of a first linear drive mechanism  16 , over a setting angle a of 20 to 30°, for example 25°, out of a first, or print-on position A into a second, or print-off position B, which second position is shown by dashed lines in FIG.  1 . In this embodiment, the first linear drive mechanism  16  can consist of a work cylinder  17 , for example of a double-action, compressed air cylinder, that is pivotably seated in a lateral frame of the printing press. The free end of a piston rod  18  of cylinder  17  is connected, through a joint  20 , with a first bracket  19  which is fastened to the side of the first, inner eccentric cylinder bushing  09 . A second bracket  21 , whose free end is used as a support, is arranged at approximately 90 degrees with respect to the first bracket  19 , on the side of the first, inner eccentric cylinder bushing  09 . In the first, print-on position A, this support  21  works in cooperation with a stop  22  that is fixed on the lateral frame. In this preferred embodiment, the stop  22  can be embodied as a sliding bearing  22 , for example. 
     The second, outer eccentric cylinder bushing  12  can be pivoted, for example by the use of a second linear drive mechanism  24 , over a setting angle βof approximately two to five degrees, for example of three degrees, out of a first or wide setting C of the printing gap  06  into a second or narrow setting D of the printing gap  06 . 
     The second linear drive mechanism  24  can, for example, consist of a threaded spindle drive, or of a worm drive  27 , and is hinged on the lateral press frame and is operable by use of a hand wheel  26 . A free end  28  of the threaded spindle  29 , or worm drive  27  that forms the second linear drive mechanism  24 , is connected, via a joint  30 , to a third bracket  31 , which is fastened on the side of the second, outer eccentric cylinder bushing  12 . 
     The arrangement for setting the spacing between the rotational axes of cylinders, in accordance with the present invention, operates as follows. The rubber blanket cylinder  01  can be brought from the first print-on position A into the second print-off position B by actuating the working cylinder  17 , and thus rotating the first, inner eccentric cylinder bushing  09 , as seen in FIG.  1 . In the process, the existing printing gap  06  between the first and second rubber blanket cylinders  01 ,  04  is increased to a print-off position, and simultaneously a printing gap  06  between the first rubber blanket cylinder  01  and the forme cylinder  03  is increased also to a print-off position. 
     The second rubber blanket cylinder, or counter-pressure cylinder  04  can also be displaced from a print-on position G into a print-off position H by supporting it in eccentric bushes, which are not specifically represented. 
     Because of the activation of the second linear drive  24 , for displacing the second, outer eccentric cylinder bushing  12 , it is possible, in the print-on position A of the rubber blanket cylinder  01 , to achieve a change of the width of the printing gap  06 , for example from −50 μm to +100 μm from the set zero position. This takes place between the narrow setting D and the wide setting C of the printing gap  06  as shown in FIG. 2, for example between ±50 μm. 
     The effective direction of the eccentricity “f” of the second, outer cylinder bushing  12  extends approximately parallel with an imaginary connecting line  32  extending between the axis of rotation  08  of the first rubber blanket cylinder  01  and an axis of rotation, which is not specifically represented, of the adjoining forme cylinder  03 . 
     The axes of rotation  08  of the first rubber blanket cylinder  01 , and of the second rubber blanket cylinder  04  are connected by the imagined connecting line  33 , as may also be seen in FIG.  1 . 
     If, because of, for example, a reduced paper thickness, the printing gap  06  between the cylinders  01 ,  04  existing in the print-on position A is to be changed from a normal position O, for example for a paper weight or density of 80 g/m 2 , to a narrow setting D, the linear drive  24  is moved to the left, as shown in FIG.  2 . 
     If a wide setting C of the printing gap  06  is to be achieved, the linear drive  24  is moved from the normal position O in the opposite direction, again as seen in FIG.  2 . 
     In the course of the displacement of the second, outer eccentric cylinder bushing  12  about its axis of rotation  13  by operation of the second linear drive  24 , the first, inner eccentric cylinder bushing  09 , as well as the support  21  are displaced on the sliding bearing  22 . The axis of rotation  11  of the first, inner eccentric cylinder bushing  09  changes its position O-C, or O-D in a direction that is parallel with a setting curve  34  of the paper thickness described by the axis of rotation  08  of the first rubber blanket cylinder  01  when the paper thickness changes. 
     Each point on the setting curve  34  has approximately the same distance to the axis of rotation of the forme cylinder  03  and therefore does not change this distance. Accordingly, the periphery  02  of the first rubber blanket cylinder  01  remains in the vicinity of the periphery of the forme cylinder  03 . 
     Approximately parallel is to be understood to be an opening angle between two straight lines of ±10°, in particular ±5°. 
     While a preferred embodiment of an arrangement for setting the spacing between the rotational axes of cylinders in accordance with the present invention has been set forth fully and completely hereinabove, it will be apparent to one of skill in the art that various changes in, for example, the specific type of printing press used, the overall sizes of the cylinders, and the like could be made without departing from the true spirit and scope of the present invention which is accordingly to be limited only by the following claims.