Printing unit for a web-fed offset rotary press

In a web-fed offset rotary press printing unit comprising four cylinders (2-5), in order to move the two inner cylinders, for instance blanket cylinders (3, 4), apart from one another without having to move the outer cylinders (2, 5), the cylinder trunnions (6, 7) of the inner cylinders (3, 4) are positioned on double eccentric bushes (8, 9; 10, 11). By means of tie rods (16-19), all the pairs of eccentric bushes (8, 9; 10, 11) are pivoted in common about the same angle, resulting in a linear movement in opposite directions (P or P') by the inner cylinders (3, 4) with respect to the straight line (G) on which the four cylinders are disposed.

The invention relates to a printing unit for a web-fed offset rotary press, 
or printing machine, in which four cylinders of the printing unit are 
disposed one above the other on a straight line extending obliquely with 
respect to an approximately horizontal web of material to be printed. The 
web can be fed between the two inner cylinders, which are embodied as 
rubber cylinders, and the cylinders can be moved apart from one another by 
means of eccentric adjusting means. 
BACKGROUND 
From German Patent Disclosure Document DE-OS 32 37 961.7-27, a web-fed 
offset rotary printing machine is already known which has a number of 
printing units of the above-specified type disposed in succession in it. 
If the two middle cylinder, as a rule the rubber blanket cylinders, of 
such printing units are to be separated from one another, for instance in 
order to fasten new blankets onto them, then at least one of the outer 
cylinders must first be pivoted out of the way. The trunnions of all the 
printing unit cylinders are supported in eccentric bushes, so that the 
desired positioning movements into and out of the position for printing 
can be executed in the appropriate sequence by rotating the eccentric 
bushes. 
THE INVENTION 
It is an object to enable separating the two middle cylinders in a printing 
unit of the above type using a single control mechanism, without having 
first to pivot the outer cylinders out of the way. 
Briefly, the eccentric bushes of the middle cylinders are disposed in 
pairs, one inside the other, with each pair located in a bore in each 
middle cylinder and supported in the side walls; the pairs have the same 
eccentricity. The outer bushes of each pair are joined by one common tie 
rod, and the inner bushes of each pair are joined by another tie rod. By 
means of two further tie rods respectively joining one inner and one outer 
bush of a pair to a control device, all the eccentric bushes can be 
rotated about the same angle, causing the two middle cylinders to move in 
opposite directions, at right angles to the oblique straight line on which 
the printing unit cylinders are disposed when in operation. The outer 
cylinders of the printing unit do not need to be moved. 
Although supporting the axial trunnions of a cylinder in a double eccenter 
in the side walls of a printing unit is already known from examined German 
Patent Application DE-AS 27 25 030, the pairs of eccentric bushes in that 
case are adjusted via two levers rotatable independently of one another; 
with these two levers, only one cylinder at a time is moved toward two 
adjacent cylinders or raised away from them. In the concept of a printing 
unit according to the invention, in contrast, there is the advantage that 
two middle cylinders, that is, two cylinders positioned between two outer 
cylinders that are disposed on approximately the same common center line, 
can be separated from and moved toward one another by using a single 
control device; in the course of this movement the middle, or blanket 
cylinders are separated from the associated outer cylinders, typically 
plate cylinders, as well. Hence it is no longer necessary for the outer 
cylinders to be positioned in such a way, for instance in an eccenter, 
that they are pivotable. 
The invention will be described in further detail below, referring to the 
drawing.

The structural components shown in all three Figures are identical and, 
thus, the same reference numerals have been used in all three Figures. 
Where appropriate, prime notation has been used for distinction between 
elements in respective embodiments. 
DETAILED DESCRIPTION 
For multi-color printing on both sides of a web T of material to be 
printed, a plurality of printing units such as the unit 1 shown in the 
drawing may be disposed in succession. Such printing units each include 
four cylinders 2, 3, 4, 5 disposed one above the other and positioned 
approximately on a common center line G. The cylinders accordingly are 
supported on each other, so that the danger of sagging, with the attendant 
impairment of printing quality, is thereby avoided or lessened. As shown 
in the drawing, the web T that is to be printed is fed approximately 
horizontally through the two middle cylinders 3, 4, which are the rubber 
blanket cylinders, in order that the web will be printed on both sides. To 
assure that the web will properly wrap itself about the two inner 
cylinders 3, 4, the straight line G is more or less oblique; that is, it 
is not at right angles to the direction in which the web T moves. In the 
printing unit 1 according to the invention, it is no longer absolutely 
necessary for the two outer cylinders 2, 5, which in an offset printing 
unit are the plate cylinders, to be positioned in eccentric bearings; such 
a positioning is shown in the drawing in broken lines. 
Bores A, B for supporting the two middle cylinders 3, 4 are provided in 
each side wall 1 of the printing unit shown, which is intended for a 
web-fed offset rotary press. In these bores, the cylinder trunnions 6, 7 
of rubber blanket cylinders 3, 4 are positioned in respective pairs of 
eccentric bushes; these pairs comprise an eccentrically drilled outer bush 
8 and an eccentrically drilled inner bush 9 for the cylinder trunnion 6, 
and an eccentrically drilled outer bush 10 and an eccentrically drilled 
inner bush 11 for the cylinder trunnion 7. One of a group of adjusting 
levers 12, 13, 14, 15 is associated with each of the eccentric bushes 
8-11. The adjusting levers 12, 14 for the inner eccentric bushes 9, 11 are 
joined by a tie rod 17, and the adjusting levers 13, 15 for the outer 
eccentric bushes 8, 10 are joined by a tie rod 16. A control or adjusting 
device is also joined to one of the pairs, for instance the lower one, of 
eccentric bushes, and with the aid of this control device the eccentric 
bushes 10, 11 are rotatable via tie rods 18, 19. The movement of the tie 
rods 18, 19 and hence the rotation of the eccentric bushes 10, 11 is 
effected with the aid of a control device which includes a pivot lever 20 
disposed on an adjusting spindle 21. The adjusting spindle 21 may be 
rotated by motor or manually. If the adjusting spindle 21 is rotated 
clockwise, for instance, the tie rods 16-19 assume the position indicated 
by broken lines, resulting in a corresponding rotation of the eccentric 
bushes 8-11. The adjusting levers 12-15 and the tie rods 16-19 are 
dimensioned such that all the eccentric bushes 8-11 are rotated by the 
same amount, that is, about the same angle, when the adjusting spindle 21 
rotates. It is thereby assured that when the cylinders are moved into and 
out of their operational positions, the inner eccentric bush 9 is rotated 
by the same angular amount as the outer eccentric bush 8, but in the 
opposite direction. The same applies to the inner eccentric bush 11 and 
the outer eccentric bush 10. It would also be possible, however, for the 
tie rods 18, 19 to act directly upon the tie rods 16, 17. 
By means of the above-described advantageous embodiment of the adjusting 
levers 12-15 and tie rods 16-19, it is attained that with a single control 
device 20, 21 and with the outer cylinders 2, 5 remaining stationary, the 
inner cylinders 3, 4 can be moved simultaneously, but in opposite 
directions P and P' respectively, in a straight line toward or away from 
the common straight line G and at an angle of 90.degree. thereto. This 
makes it possible to separate the inner cylinders 3, 4 from one another 
and from the cylinders 2, 5, by moving the upper inner cylinder 3 toward 
the left and the lower inner cylinder 4 toward the right. The cylinders 3, 
4 are thus separated, for instance in order to change their rubber 
blankets. In the course of this movement, they also move away from the 
respective outer cylinders 2 and 5. If the movement is in the opposite 
direction, the inner cylinders 3, 4 are moved into their operational 
position; that is, they are each moved in the direction P toward the 
straight line G until they touch one another and also touch the outer 
cylinders 2 and 5, respectively. Although it is not absolutely necessary, 
it may be useful to support the outer cylinders eccentrically, as 
indicated by broken lines in the drawing. This also makes it possible to 
adjust the positioning force individually between the outer cylinder, such 
as 2, and the associated inner cylinder, such as 3, to the desired value. 
Reference numerals 22, 23 indicate the centers of the cylinders 3, 4 in the 
separated or non-operational position, and reference numerals 24, 25 
indicate the cylinder centers in the operational position. At the same 
time, reference numerals 24, 25 also indicate the center of the bore as 
well as the center of the inner eccentric bushes 9, 11; contrarily, 
reference numerals 26, 27 represent the centers of the bores of the outer 
eccentric bushes 8, 10. In summary, reference numerals 22, 23 show that 
the above-mentioned center points of the upper inner cylinder 3 always 
come to rest on the left side of the common straight line G, while the 
above-mentioned center points of the lower inner cylinder 4 come to rest 
on the right side of the common straight line G. As a result, upon a 
movement of the inner cylinders 3, 4 in the direction of the arrow P 
(positioning movement, i.e., an approach toward one another for 
operation), the cylinders 3, 4 can be positioned against one another with 
the required force. In the operational position, the cylinder centers 22, 
23 should be as close as possible to the common straight line G. 
The positioning force among the cylinders 2-5 is preferably not effected 
via the control device 20, 21. 
The positioning force between the inner cylinders 3, 4 and between them and 
the respective outer cylinders 2, 5 is effected by means of the 
turnbuckles 28 located in the rods 16, 17, 18 and 19 and having a 
left-handed and right-handed threads. The turnbuckles extend or shorten 
the tie rods 16, 17, 18, 19 and thereby rotate the eccentric bushes 8, 9, 
10 and 11 individually. 
The difference between the embodiments of FIG. 1 and FIGS. 2 and 3 is the 
arrangement of the motion of switching the inner cylinders 3, 4 in the 
direction P or P', respectively, with respect to the common line G. In 
FIG. 2, the movement is, slightly divergent, towards the right; in FIG. 3, 
the movement is, slightly divergent, towards the left. Of course, for 
engagement, the movement is reversed. By this arrangement, the cylinders 
3, 4 are separated from each other and from the outer cylinders 2, 5. The 
switching arrangement is identical to that of FIG. 1; only the eccentric 
bushes have different positions which, specifically, differ by 180.degree. 
from each other. 
In the arrangement of FIGS. 2 and 3, likewise, it may be desirable to 
provide eccentric bushes for the outer cylinders 2, 5, but this is not 
necessary; likewise, the engagement force can be controlled by 
turnbuckles. 
In FIGS. 2 and 3, the reference numerals 26',27' and 26", 27" correspond, 
respectively, to the reference numerals 26, 27 of FIG. 1, and relate to 
the center of the bores of the outer eccenter bushes 8, 10. 
In the arrangement in accordance with FIGS. 2 and 3, the points designated 
by reference numerals 22, 27' and 22, 27", and hence the centers of the 
cylinders 3, 4, are either at the right side (FIG. 2) or at the left side 
(FIG. 3) of the theoretical connecting line G between the centers of the 
outer cylinders 2, 5. This insures movement of the inner cylinders 3, 4, 
in direction of the arrow P for engagement, and permits engaging the 
cylinders 3, 4, with the necessary impression force with respect to each 
other. Preferably, the centers of the cylinders, shown at reference points 
24, 25, should be close to the common theoretical line G. In the 
embodiments of FIGS. 2 and 3, it is desirable that the outer cylinders 2, 
5 are slightly offset laterally with respect to the theoretical line G; in 
FIG. 2, the offset would be towards the left, in FIG. 3, the offset would 
be towards the right. This facilitates movement of the inner cylinders 3, 
4, towards the right (FIG. 2) or towards the left (FIG. 3) when it is 
desired to separate the cylinders. Although the theoretical connecting 
line G is shown to pass through the centers, the line G may also be 
thought of as passing through the tangential engagement points between the 
cylinders 2, 5 and the engaging cylinders 3, 4, when in engaged position. 
Various changes and modifications may be made within the scope of the 
inventive concept.