Printing press having cantilevered self-driven cylinders

In order to facilitate removal and replacement of blanket and impression sleeves in a rotary offset printing press, the blanket and plate cylinders are supported in cantilever fashion. The cantilevered cylinders allow axial removal and replacement of the blanket and impression sleeves without temporary support of the cylinder and without removal of any bearings. Each cylinder is rotatably supported on a cantilevered support shaft having a bore therethrough. A drive shaft operatively connected to a drive motor extends through the support shaft bore and engages the inner surface of the generally hollow cylinder. A blanket or impression sleeve mounted on the cylinder is removable using compressed air, which is routed through a bore in the drive shaft and through a plurality of radially oriented passage in a flange on the end of the drive shaft. Each radial passage communicates air to an exit port on the surface of the cylinder, which introduces enough air between the cylinder and the sleeve to permit the sleeve to slide freely for axial removal and replacement.

FIELD OF THE INVENTION 
The present invention relates generally to a rotary offset printing press 
having removable impression and blanket sleeves mounted on axially 
rotatable plate and blanket cylinders, respectively. More specifically, 
the present invention relates to cantilevered self-driven cylinders for 
rotary presses which permit the axial removal and replacement of the 
sleeves, and which improve print quality, reduce downtime, and minimize 
drive line related problems. 
BACKGROUND OF THE INVENTION 
Rotary offset printing presses having rotatable cylinders and removable 
impression and blanket sleeves are generally well known in the art. Such 
presses typically operate at very high speeds and are capable of printing 
a high quantity of material in a relatively short period of time. A 
continuous web of paper passes between a pair of rotating blanket 
cylinders which print images on opposites sides of the paper web. Each 
blanket cylinder is in contact with a plate cylinder having an impression 
sleeve which has been inked and dampened and which transfers the images to 
the blanket cylinder for printing onto the web in a manner well known in 
the art. 
In order to change the printed material, such as when a newspaper, magazine 
or brochure is switched to a different edition, the plate cylinder is 
moved away from its adjacent blanket cylinder, the impression sleeve on 
the plate cylinder is removed, and a different impression sleeve is 
installed. When the changeover process is complete the press is ready for 
the next printing run. 
Many times, such changeovers occur with great frequency, such as when small 
jobs are being printed. Unfortunately, the process of changing the 
impression sleeve is very labor intensive and time consuming, and thus 
there is considerable down time for the press. Typically, each cylinder in 
the press is mounted for axial rotation between a pair of spaced apart 
side walls. The impression sleeves are mounted to the cylinders, and fit 
so snugly that the sleeves are held in place by friction. In order to move 
the sleeve relative to the cylinder, compressed air is forced between the 
inner surface of the sleeve and the outer surface of the supporting 
cylinder. The cushion of air expands the sleeve slightly, and allows the 
sleeve to slide relative to the cylinder. Thus, in order to install or 
remove the impression sleeve from the plate cylinder, the plate cylinder 
must first be disconnected and removed from the side walls. Thereafter, a 
new impression sleeve is placed on the cylinder in the same manner and the 
rotatable cylinder is reinstalled in preparation for the next printing 
run. As outlined above, this is a very time consuming process and 
seriously undermines the cost effectiveness of the press when the press is 
being used on relatively small jobs. 
A number of approaches have been attempted in order to decrease the 
changeover time between printing runs. For example, one approach as 
disclosed in U.S. Pat. No. 4,807,527 is to provide a releasable bearing on 
one end of the cylinder shaft. Removal of the bearing assembly creates an 
access hole in the press side wall and exposes one end of the cylinder 
shaft so that the impression sleeve can slide off the shaft through the 
access hole. The other end of the shaft is elongated, and during the 
changeover process the elongated portion of the shaft abuts an auxiliary 
shaft which is put in place for temporary support. 
Similarly, U.S. Pat. No. Re. 34,970 discloses a pivotable bearing which 
swings away to free up one end of the cylinder for the removal of the 
sleeve, and also discloses a cylinder supported by a pair of linearly 
retractable bearings, and finally a cylinder mounted to a swivel on one 
end and having a retractable bearing on the other. 
Unfortunately, in addition to other shortcomings, each of the prior art 
devices requires some means of temporary cylinder support in order to 
effectuate the changeover of the impression sleeve. In addition, each of 
the prior art devices requires that at least one of the bearing assemblies 
be completely disconnected from the cylinder shaft, and thus, neither of 
these approaches provides a cost effective solution to the problems 
outlined above. 
Another problem with prior art printing presses is that all of the rotating 
cylinders in the machine are mechanically connected to a single drive 
shaft system, which creates a number of inherent drawbacks. For example, 
all of the rotating cylinders and rollers in a printing press are 
typically connected to a common drive system, which consist of an 
extensive collection of drive shafts, gearboxes and pulleys, all of which 
is designed to spin all of the cylinders in the press at the same 
peripheral speed. Because all of the cylinders must have access to the 
same drive system, the placement of the cylinders relative to each other 
is severely constrained, which adds to the difficulty in changing 
impression sleeves on the plate cylinders. Moreover, on large presses 
there is noticeable lash in the drive system, which causes registration 
and vibration problems, both of which negatively impact print quality. 
Accordingly, there exists a need for a rotary offset printing press having 
cantilevered cylinders which permit fast replacement of the impression 
sleeve and which do not require temporary support during changeover. There 
also exists a need for self-driven cylinders which reduce or eliminate 
drive line lash and which also improve registration and overall system 
performance. 
SUMMARY OF THE INVENTION 
The present invention uses generally hollow cylinders mounted on 
cantilevered support shafts. The cantilevered construction completely 
eliminates much of the componentry normally required at one of the 
cylinder ends, and thus access to the cylinder for removal or replacement 
of the impression sleeve is greatly improved. During changeover no 
bearings must be disconnected and no temporary support is required and 
thus changeover times are dramatically reduced. 
The present cantilevered construction also makes possible a self-driven 
feature for the cylinders in which each cylinder has its own drive motor. 
Preferably, the drive motors are synchronized using servo-controllers, and 
thus registration is simplified, print abnormalities induced by 
conventional drive system harmonics are reduced, and drive system lash is 
eliminated. Moreover, because the cylinders need not be removed from the 
supporting structure during changeover, the drive system never needs to be 
disconnected. Finally, the placement of the plate and blanket cylinders is 
not constrained by the requirements of the drive system, and thus, the 
present invention offers much more flexibility in the placement of 
printing couples in both new and retrofitted presses. 
The present invention also incorporates a pair of rotatable adjustment 
members which enable the angle of the support shafts and their attached 
cylinders relative to the supporting frame to be precisely controlled. The 
adjustment members are tapered, and may be manipulated to vary the bias 
angle between zero bias and a maximum bias. The adjustable bias angle thus 
ensures that the blanket cylinders and the plate cylinders will have a 
uniform contact pressure along there entire length, which greatly improves 
print quality. 
Accordingly, it is an object of this invention to provide an improved 
rotary offset printing press. 
It is another object of this invention to provide a rotary printing press 
having cantilevered cylinders which greatly reduce changeover time. 
A further object of this invention is to provide self-driven cylinders 
which improve system performance and which eliminate drive line lash. 
A still further object of the invention is to provide blanket cylinders and 
plate cylinders having adjustable bias angles. 
These and other objects of the invention will become readily apparent to 
those skilled in the art upon a reading of the following description with 
reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The embodiments described herein are not intended to be exhaustive or to 
limit the invention to the precise form disclosed. They have been chosen 
and described in order to best explain the principles of the invention and 
its practical use in order to enable others skilled in the art to follow 
its teachings. 
Referring now to the drawings, FIG. 1 illustrates a rotary offset printing 
press incorporating the features of the present invention and which is 
generally referred to by the reference numeral 10. Press 10 includes a 
frame 12 and a pair of opposing side walls 14, 16. Press 10 also includes 
a pair of blanket cylinder assemblies 18, 20 between which passes a web of 
paper (not shown) to be printed. Each of the blanket cylinder assemblies 
18, 20 is disposed adjacent a pair of plate cylinder assemblies 22, 24 and 
26, 28, respectively. Blanket cylinder assemblies 18, 20 each support a 
generally hollow rotatable blanket cylinder 19, 21, respectively, and 
plate cylinder assemblies 22, 24, and 26, 28 each support a generally 
hollow rotatable plate cylinder 23, 25, and 27, 29, respectively, in a 
manner which will be explained in greater detail below. Preferably, plate 
cylinder assemblies 22, 24 are interchangeable, i.e., one or the other can 
be used for printing at any given time, as are plate cylinder assemblies 
26, 28. Consequently, blanket cylinder assemblies 18, 20 are in contact 
with only one of their adjacent plate cylinder assemblies 22, 24 or 26, 28 
during operation of the press 10. Each of blanket cylinder assemblies 18, 
20 and plate cylinder assemblies 22, 24 and 26, 28 are mounted in 
cantilever fashion to side wall 14 in a manner which will be discussed in 
greater detail below. 
Press 10 also includes a pair of ink roller assemblies 30, 32, each of 
which includes a plurality of individual inking rollers. Ink roller 
assemblies 30, 32 apply ink and/or a dampening solution to their adjacent 
plate cylinders 22, 24 and 26, 28 respectively, in a manner well known in 
the art. Ink roller assemblies 30, 32 are rotatably mounted between side 
walls 14, 16 in a conventional manner. 
Referring now to FIG. 2, blanket cylinder assembly 20 and plate cylinder 
assembly 28 are shown mounted in side-by-side cantilever fashion to side 
wall 14. It will be understood that the structure, function and operation 
of blanket cylinder assembly 18 and its adjacent plate cylinder assemblies 
22, 24 is substantially the same as the structure, function and operation 
of cylinder assemblies 20 and 28 shown in FIG. 2. Similarly, the 
structure, function and operation of plate cylinder assembly 26 is 
substantially the same as plate cylinder assembly 28. Accordingly, only 
blanket cylinder assembly 20 and plate cylinder assembly 28 will be 
described in detail. 
Blanket cylinder assembly 20 includes a support shaft 34 having a 
cylindrical base 35 which extends through a bore 36 in a carriage 37. 
Support shaft 34 also includes a shoulder 112 which abuts a pair of 
adjustment members 114, 116, which are used to alter the angle of support 
shaft 34 relative to side wall 14 as is explained in greater detail below. 
Support shaft 34 is rigidly secured to carriage 37 by a plurality of 
mounting bolts 38. Carriage 37 is slidably mounted in a slot 39 in side 
wall 14, and is supported for linear movement within slot 39 on a 
plurality of linear bearing sets 40. Carriage 37 thus permits the blanket 
cylinder assembly 20 to slide along a path perpendicular to the axis of 
support shaft 34. Support shaft 34 includes a generally cylindrical outer 
surface 44 and an inboard set of bearings 46 and an outboard set of 
bearings 48 which rotatably support the blanket cylinder 21. Support shaft 
34 also includes a central longitudinal bore 42, the purpose of which is 
discussed in greater detail below. Blanket cylinder 21 includes an 
internal cavity 31, which is sized to fit over support shaft 34. A 
removable cylindrical blanket sleeve 52 fits over the outer surface of 
blanket cylinder 21 and is held in place by friction. 
A drive shaft 54 extends through bore 42 of support shaft 34 and is 
operatively connected to a drive motor 56 by a splined coupling 58. Drive 
motor 56 is preferably connected to a commercially available 
servo-controller 57, which permits the rotational orientation of the 
cylinder 21 to be controlled. Drive shaft 54 includes an outer end 60 
having a circular mounting flange 62 which is mounted to an annular seat 
65 on the inner surface of cylinder 21 by a plurality of mounting bolts 64 
spaced circumferentially about the flange 62. As can be seen in FIGS. 2 
and 6, flange 62 also includes a plurality of radially extending bores 66 
which are aligned with a plurality of circumferentially spaced exit ports 
67 through the outer surface of the blanket cylinder 21. Outer end 60 of 
drive shaft 54 also includes a bore 68 which intersects each of the 
plurality of radial bores 66. An air fitting 70 is affixed to the end 60 
of drive shaft 54, which permits compressed air from a supply source (not 
shown) to be routed through ports 67 via bore 68 and radial bores 66, in 
order to permit the removal of sleeve 52 from blanket cylinder 21 in a 
manner commonly employed in the art. Moreover, because the blanket 
cylinder 21 is supported in true cantilever fashion, the sleeve 52 can be 
removed from blanket cylinder 21 without disconnecting bearing assemblies 
or providing temporary support since there is no interference from side 
wall 16 or from the drive system. 
Referring now to the plate cylinder assembly 28, which is shown on the top 
when viewing FIG. 2, it includes a support shaft 72 having an eccentric 
base 73 which extends through a bore 74 in side wall 14. Support shaft 72 
also includes a shoulder 75 which abuts a pair of adjustment members 114, 
116, which are used to alter the angle of support shaft 72 relative to 
side wall 14 as is explained in greater detail below. Support shaft 72 is 
secured to side wall 14 by a plurality of mounting bolts 76, thrust washer 
78, and thrust bearings 80. Thrush washer 78 and thrust bearings 80 permit 
the rotation of support shaft 72 about its eccentric base 73 using a throw 
off lever (not shown) in order to move plate cylinder assembly 28 towards 
or away from blanket cylinder assembly 20 during changeover, maintenance, 
or adjustments of press 10. 
Support shaft 72 includes a generally cylindrical outer surface 82 and an 
inboard set of bearings 84 and an outboard set of bearings 86 which 
rotatably support the plate cylinder 29. Support shaft 72 also includes a 
central longitudinal bore 88. A removable cylindrical plate or impression 
sleeve 90 fits over the outer surface of plate cylinder 29 and is held in 
place by friction. Plate cylinder 29 includes an internal cavity 33, which 
is sized to fit over support shaft 72. A drive shaft 92 extends through 
bore 88 of support shaft 72 and is operatively connected to a drive motor 
94 by a splined coupling 96. Drive motor 94 is also connected to 
servo-controller 57. Drive shaft 92 includes an outer end 98 having a 
circular mounting flange 100 which is mounted to an annular seat 102 on 
the inner surface of cylinder 29 by a plurality of mounting bolts 104 
spaced circumferentially about the flange 100. Flange 100 also includes a 
plurality of radially extending bores 106 which are aligned with a 
plurality of circumferentially spaced exit ports 107 through the outer 
surface of plate cylinder 29. Outer end 98 of drive shaft 92 also includes 
a bore 108 which intersects each of the plurality of radial bores 106. An 
air fitting 110 is affixed to the end 98 of drive shaft 92, which permits 
compressed air from a supply source (not shown) to be routed through ports 
107 via bore 108 and radial bores 106, in order to permit the removal of 
plate or impression sleeve 90 from cylinder 29 in a manner commonly 
employed in the art. As with the blanket cylinder 21, because the plate 
cylinder 29 is supported in true cantilever fashion, the removal of 
impression sleeve 90 can be accomplished without disconnecting bearing 
assemblies or providing temporary support since there is no interference 
from side wall 16 or the drive system. 
Referring now to FIGS. 3 through 5, adjustment members 114, 116 each 
include a tab or handle 115, 117 and a central bore 119, 121, 
respectively, which is sized to fit over the base 35 or 73 of their 
corresponding support shafts 34 or 72. As shown in FIGS. 4 and 5, 
adjustment member 114 includes a narrowed portion 122 and a thickened 
portion 124, while adjustment member 116 includes a narrowed portion 126 
and a thickened portion 128. As can be seen in FIG. 2, a set of adjustment 
members 114, 116 is disposed about each of the bases 35 and 73 of shafts 
34 and 72 in abutment with the shoulders 112, 75, respectively. Moreover, 
the adjustment members 114, 116 are wedged between the shoulders 112 and 
75 of the support shafts 34 and 72 and the carriage 37 and side wall 14, 
respectively. 
In operation, the support shaft 34 is mounted to carriage 37 with the 
adjustment members 114, 116 abutting the shoulder 112 adjacent the base 
35. The members 114, 116 are rotated to the position shown in FIG. 4 to 
achieve a zero bias angle, or to the position shown in FIG. 5 to achieve a 
maximum bias angle. Alternatively, the adjustment members 114, 116 may be 
positioned in a plurality of intermediate positions. When the shaft 34 is 
secured to the carriage 37 using mounting bolts 38, the wedging action of 
the adjustment members 114, 116, when adjusted to achieve a desired bias 
angle, effectively bends the shaft 34 slightly. Thus, and by similarly 
using the adjustment members 114, 116 associated with the support shaft 
72, the ends of the respective cylinder assemblies 20, 28 may be brought 
closer together or moved farther apart, in order to achieve a generally 
uniform contact pressure along the lengths of the cylinder assemblies 20 
and 28. 
Blanket cylinder 21 is mounted on stationary support shaft 34 on the 
bearing assemblies 46 and 48, and the drive shaft 54 is inserted through 
bore 42, with flange 62 being secured to the annular seat 65 by bolts 64. 
Drive motor 56 is mounted to carriage 37 in a conventional manner and 
operatively connected to drive shaft 54 via splined coupling 58. 
Similarly, plate cylinder 29 is mounted on stationary support shaft 72 on 
the bearing assemblies 84 and 86, and the drive shaft 92 is inserted 
through bore 88, with flange 100 being secured to the annular seat 102 by 
bolts 104. Drive motor 94 is mounted to eccentric base 73 of shaft 72 in a 
conventional manner and is operatively connected to drive shaft 92 via 
splined coupling 96. Finally, servo-controller 57 facilitates the proper 
registration of cylinder 21 relative to cylinder 29, and also ensures that 
the cylinders 21, 29 remain synchronized and spin at the same peripheral 
speed. 
It will be understood that the above description does not limit the 
invention to the above-given details. It is contemplated that various 
modifications and substitutions can be made without departing from the 
spirit and scope of the following claims.