Paper sheet guiding cylinder for a printing machine

A printing machine has side frames and a printing machine drive. A paper sheet guiding cylinder is mounted in the side frames of the printing machine, is drivingly connected to the printing machine drive and has an axis. The paper sheet guiding cylinder includes a cylindrical casing and side walls with through holes formed therein. The paper sheet guiding cylinder has a rotatably mounted radial ventilator being coaxial with the axis of the paper sheet guiding cylinder for supplying blowing air into the paper sheet guiding cylinder and for deflecting the blowing air inside the paper sheet guiding cylinder towards the cylindrical casing. The radial ventilator has end surfaces communicating with the ambient air through the holes and ventilator blades being disposed concentrically about the axis of the paper sheet guiding cylinder and extending along the paper sheet guiding cylinder. A drive for the paper sheet guiding cylinder has adjustable speed and is independent of the paper sheet guiding cylinder.

CROSS-REFERENCE TO RELATED APPLICATION 
This application is a Continuation of International Application Serial No. 
PCT/EP93/01542, filed Jun. 17, 1993. 
BACKGROUND OF THE INVENTION 
Field of the Invention 
The invention relates to a paper sheet guiding cylinder for a printing 
machine that is mounted in side frames of the machine, and has a driving 
connection to a printing machine drive, a casing surface provided with 
through holes, means for supplying blowing air into the paper sheet 
guiding cylinder, and means located inside the paper sheet guiding 
cylinder for deflecting the blowing air in the direction of the 
cylindrical casing. 
Paper sheet guiding cylinders are known in the art to be used in printing 
machines to transport printed paper sheets between printing units or in a 
deliver section. The paper sheet should also be guided stably and 
smear-free with printed sheets having a printed side which is oriented 
towards the outer casing of the latter sheet guiding cylinder. The outer 
casings are also known in the art to be provided with expensive special 
coatings. The paper sheet guiding cylinders are additionally known in the 
art to be provided with blowing air passed from their interior to the 
outer casing and to the exterior by means of blow jets being oriented 
towards and connected non-rotatably to the paper sheet guiding cylinder 
and with a complex external blowing air supply. The blowing air jets only 
cover a certain part of the paper sheet guiding area. In order to cover a 
larger part of the paper sheet guiding area it is necessary to place 
several rows of blow jets in close succession one after the other. The 
external blowing air supply requires a large number of sealing means, air 
supply means and a complex blowing air control system. 
According to German Published, Non-Prosecuted Application DE 36 38 452 A1 
it is also known to place air blades for deflecting the blowing air to the 
exterior inside a paper sheet guiding cylinder and to non-rotatably 
connect the air blades to the paper sheet guiding cylinder. It is possible 
to use such air blades to adequately supply the cylinder surface with an 
air cushion at high speeds in such a way that the printed side of a paper 
sheet does not come into contact with the outer casing of the paper sheet 
guiding cylinder and therefore to largely avoid smearing effects. However, 
when printing conditions are altered and at low speeds in particular, the 
air supply is not enough to prevent further touching contacts. Therefore, 
wide working areas, for example proof printing or production run printing 
of highly accurate special orders that are usually printed at slow speeds, 
cannot be reliably transported free from smears. On one hand, if the 
machine stops suddenly the paper sheets can simply collapse under their 
own weight and in critical areas can even stick to the outer casings of 
the paper sheet guiding cylinder. On the other hand, at very high speeds 
that go beyond the narrow speed range of stable smear-free paper sheet 
guiding, the air cushion easily becomes too thick and additionally because 
of breakaway effects of the flow, the paper sheets can flutter and can 
also contact paper sheet guiding surfaces with their printed sides. 
SUMMARY OF THE INVENTION 
It is accordingly an object of the invention to provide a paper sheet 
guiding cylinder for a printing machine, which overcomes the 
hereinafore-mentioned disadvantages of the heretofore-known devices of 
this general type and which achieves a stable guiding of printed 
paper-sheets with simple means. 
With the foregoing and other objects in view there is provided, in 
accordance with the invention, in a printing machine having side frames 
and a printing machine drive, a paper sheet guiding cylinder assembly 
comprising a paper sheet guiding cylinder being mounted in the side frames 
of the printing machine and being drivingly connected to the printing 
machine drive; the paper sheet guiding cylinder having an axis; the paper 
sheet guiding cylinder including a cylindrical casing and side walls with 
through holes formed therein; the paper sheet guiding cylinder having a 
rotatably mounted radial ventilator being coaxial with the axis of the 
paper sheet guiding cylinder for supplying blowing air into the paper 
sheet guiding cylinder and for deflecting the blowing air inside the paper 
sheet guiding cylinder towards the cylindrical casing, the radial 
ventilator having end surfaces communicating with the ambient air through 
through the holes, and ventilator blades being disposed concentrically 
about the axis of the paper sheet guiding cylinder and extending along the 
paper sheet guiding cylinder; and means being independent of the paper 
sheet guiding cylinder for driving the radial ventilator with adjustable 
speed. 
The radial ventilator that is rotatably mounted in relation to and is 
driven independently of the paper sheet guiding cylinder facilitates 
stable paper sheet guiding over the full working area. Both during a 
machine stop as well as during very high speeds, an air cushion that is 
necessary for stable paper sheet guiding can be set individually because 
of the radial ventilator speed control that is independent from the paper 
sheet guiding cylinder. Even in the event of a very abrupt machine stop, 
the side of the printed paper sheet can be prevented from sticking to the 
paper sheet guiding cylinder. Stable paper sheet guiding is guaranteed 
over the full paper sheet guiding cylinder. The through holes in the front 
walls of the paper sheet guiding cylinder facilitate an adequate air 
supply without additional external complexity. The large amount of 
maintenance and assembly work involved by external air supply means 
becomes redundant. Stable paper sheet guiding is achieved by simple means. 
No additional provision of space for complex air supply means is 
necessary. The complexity of the control system for controlling the radial 
ventilator is low as compared with the known control system for external 
supply. The reduction in smearing effect leads to a reduction in paper 
wastage, an improvement in the quality of the printed paper sheets because 
of the absence of ink carry-over onto subsequent paper sheets and a 
reduction in the amount of cleaning needed for the paper sheet cylinder. 
In accordance with another feature of the invention, the radial ventilator 
has sides facing the side walls of the paper sheet guiding cylinder and 
inlet nozzles non-rotatably connected with the radial ventilator on at 
least one of the sides of the radial ventilator. This embodiment 
facilitates an additional improvement in the supply of air to the radial 
ventilator, thus improving the adjustability of the desired cushion of air 
and the stable paper sheet guiding. Due to the improved efficiency of the 
radial ventilator it can be used more energy efficiently, the driving 
means can have a lower power and costs and space requirements for the 
driving means can be reduced. 
In accordance with a further feature of the invention, the ventilator 
blades of the radial ventilator are disposed in a ring concentric to the 
axis of the paper sheet guiding cylinder, and there is provided a 
cylindrical channel being disposed annularly within the ventilator blades, 
extending axially and terminating axially in the inlet nozzles. This 
embodiment facilitates an additional improvement in the supply of air. 
In accordance with an added feature of the invention, the radial ventilator 
includes a shaft mounted concentrically in the paper sheet guiding 
cylinder, and two circular carrier plates mounted concentrically on the 
shaft, the carrier plates each having the inlet nozzles for supplying 
blowing air to the channel, and the ventilator blades being mounted 
between and on the carrier plates. In this way, a stable, even supply of 
air over the full width of the paper sheet guiding cylinder is 
facilitated. 
In accordance with an additional feature of the invention, the paper sheet 
guiding cylinder has a given width, and there is provided a shaft having 
an axis and being rotatably mounted concentrically to and in the paper 
sheet guiding cylinder, and one or two closely interspaced carrier plates 
mounted concentrically on the shaft in the middle of the given width, the 
one or two carrier plates have lateral surfaces being opposite lateral 
surfaces if two carrier plates are used, and the ventilator blades being 
mounted on the lateral surfaces, being extended parallel to the shaft axis 
and being disposed concentrically about the shaft. This embodiment 
facilitates a stable, even supply of blowing air over the full width of 
the paper sheet guiding cylinder with particularly simple preferred means. 
In accordance with yet another feature of the invention, the radial 
ventilator has a drive shaft mounting the radial ventilator concentrically 
to the paper sheet guiding cylinder, the paper sheet guiding cylinder has 
a shaft journal, the drive shaft has an extension being extended through 
the shaft journal on one side of the paper sheet guiding cylinder through 
one of the side frames to the exterior, and the extension is drivingly 
connected to the driving means outside the one side frame. Not only does 
this embodiment facilitate a particularly simple preferred driving 
connection for the radial ventilator, but since the driving means can be 
disposed completely outside the side frame of the machine they therefore 
do not obstruct the already confined space between the side frames or 
walls of the machine. The driving means are easily accessible. The control 
circuit for the driving means can be constructed to be particularly 
simple. 
In accordance with yet a further feature of the invention, there are 
provided sprockets, gripper chains having two spans passing over the 
sprockets and having gripper rails, the outer casing of the paper sheet 
guiding cylinder having an angular paper sheet guiding region, the gripper 
rails passing around the side walls of the paper sheet guiding cylinder at 
least over the paper sheet guiding region, the side frames having inner 
surfaces, the independently controllable driving means being disposed on 
the inner surface of one of the side frames between the two spans of the 
gripper chains, and the radial ventilator having a shaft being mounted 
concentrically to the sprockets and being drivingly connected to the 
driving means. This constitutes a further embodiment of the driving 
connection. 
In accordance with yet an added feature of the invention, the driving means 
has means for varying a direction of rotation of the radial ventilator. 
This form of the invention constitutes a further tensioning of the 
transported paper sheets by the blowing air moving counter to the 
direction of transport of the paper sheets. This proves to be especially 
beneficial for the short-term machine stop in particular. 
In accordance with a concomitant feature of the invention, the radial 
ventilator has a direction of rotation being contrary to a direction of 
rotation of the paper sheet guiding cylinder. In the preferred form of 
this embodiment the direction of rotation of the radial ventilator is 
reversible. This facilitates the optimum matching of the supply of blowing 
air to the print job profile. In particular, the change from very thin 
paper sheets to very thick paper sheets and vice versa can be carried out 
particularly stably with this embodiment. 
Other features which are considered as characteristic for the invention are 
set forth in the appended claims. 
Although the invention is illustrated and described herein as embodied in a 
paper sheet guiding cylinder for a printing machine, it is nevertheless 
not intended to be limited to the details shown, since 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.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the figures of the drawing in detail and first, 
particularly, to FIGS. 1 and 2 thereof, there is seen a delivery device 1 
of a paper sheet rotary offset printing machine in which printed paper 
sheets from a printing cylinder 9 of the last printing unit are accepted 
by gripper rails 10 attached to chains 3 and are transported over a 
delivery stack 2 where they are stacked. The gripper rails are carried on 
two chains 3 between side frames 7 and 8. In the vicinity of a delivery 
drum or guiding cylinder 11, the chains 3 are each guided continuously 
over sprockets 5 and 6. The sprocket 5 is attached to a stub shaft 13 that 
is rotatably mounted in the side frame or wall 7 and has an extension on 
which a sprocket 12 is attached outside the side frame 7. The sprocket 12 
is connected with a non-illustrated printing machine drive. The sprocket 6 
is also rotatably mounted on a stub shaft 14 in the machine side frame 8 
so as to be concentric with the sprocket 5. The stub shaft 14 is 
constructed to be a hollow shaft. A shaft 16 is rotatably mounted 
concentrically to the stub shafts 13 and 14, has a shaft journal and is 
extended through the hollow stub shaft 14 to the exterior. A motor 15 is 
mounted on an extension outside the machine side frame 8 and is supported 
against the machine side frame in a known manner. The shaft 16 runs 
transversely to the paper sheet transport direction and is rotatably 
mounted at another shaft journal in the stub shaft 13. A circular carrier 
flange 17 which is mounted on the shaft 16 in the middle of the machine 
width has an outer circumferential region in which evenly spaced deflector 
blades 18 and 19 for radial ventilation are attached on both sides towards 
the machine side frames 7 and 8, over the circumference of the carrier 
flange 17. The deflector blades or plates 18 and 19 extend towards the 
exterior over the full transport width and are provided at their 
extremities with annular plates 25 and 26 oriented concentrically to the 
shaft 16. Circular flanges 20 and 21 are also attached on the stub shafts 
13 and 14 between the sprockets 5 and 6. Towards the center of the 
machine, inlet nozzles 24 are mounted on the flanges 20 and 21 so as to be 
concentric to the shaft 16. These nozzles connect a ring channel 43 
located within the deflector blades 19 between the deflector blades 19 and 
the shaft 16 with the atmosphere by means of through holes 23 which are 
distributed over the circumference of the flanges 21 and 20. Crossbars 22 
are also attached to the flanges 20 and 21, are spaced about their 
circumference and are disposed at a greater radius than the deflector 
blades 19. These crossbars extend across the full with width between the 
two flanges 20 and 21. 
Paper sheets that are transferred from the printing cylinder 9 to the 
gripper rails 10 on the continuous chains 3 are transported by the gripper 
rails 10 between guide plates 41 that are mounted in the side frames 8, 7 
and an outer surface of the crossbars 22 on the delivery drum 11. To this 
end the chains 3 are driven by the printing machine drive across the 
sprocket 12, the stub shaft 13, the flange 20, the crossbars 22, the 
flange 21 and the sprockets 5 and 8. Independently of this, the deflector 
blades 18 and 19 are driven by means of the motor 15 through the shaft 16 
and the flange 17. The deflector blades on the radial ventilator draw 
suction air through the through holes 23 in the flanges 20 and 21, across 
the inlet nozzles 24, into the channels 43 and discharge it radially and 
circumferentially as blowing or blown air to the exterior. In this way an 
adequate cushion of air for stable paper sheet guiding can be achieved 
over the entire circumference of the delivery drum. Desired operating 
profiles can be set steplessly with the aid of a motor controller for the 
motor 15. 
It is possible to use a motor 15 that is variable in its direction of 
drive. In this way, if necessary, it is possible to orient blowing air 
counter to the direction of transport of the paper sheets, as a result of 
which the trailing edge of the paper sheet is slightly tensioned against 
the leading edge of the paper sheet that is held by the gripper rails and 
as a result of which flutter effects can also be prevented. Even in the 
event of a machine stop, the motor 15 can continue to drive the deflector 
blades 19 and 18, thereby sustaining the cushion of air. 
In order to improve efficiency it is also conceivable to attach an 
additional guide plate 42 above the delivery drum and between the side 
frames of the machine, for example to isolate the remaining delivery area 
from the blowing air as well as the transport area of the printing 
cylinder. 
FIGS. 3 and 4 illustrate another embodiment of the invention. The sprockets 
5 and 6 are stationary fitted on a shaft 35 that is rotatably mounted in 
the machine side frames 7 and 8 and runs transverse to the paper sheet 
transport direction. The shaft 35 is extended through the machine side 
frame 7 towards the exterior and is in connection with the printing 
machine drive by means of a sprocket 12 that is mounted on it. A hollow 
shaft 32 is rotatably mounted between the sprockets 5 and 6 on the shaft 
35 and is coaxially to it. Two flanges 30, 31 are mounted on the hollow 
shaft 32 in the middle of the machine width. Deflector plates 28 and 29 
are mounted at ends of the flanges 30, 31 facing the side frames 7 and 8 
for radial ventilation. The deflector plates 28 and 29 are coaxial to the 
shaft 35 and evenly spaced over the outer circumference of the flanges 30 
and 31. Extreme ends of the deflector plates 28 and 29 are in turn 
attached to annular plates 25, 26 oriented coaxially to the shaft 35. 
Between the annular plate 26 and the sprocket 5 the hollow shaft 32 is 
connected by means of a drive belt 33 to a driven shaft 34 which is in 
turn connected to an independent drive motor. In this case again, the 
radial ventilator formed by the deflector plates 28, 29 sucks air from the 
atmosphere between the sprockets 5, 6 and the annular plates 25, 26 
through the channel 43 formed between the deflector plates 28, 29 and the 
hollow shaft 32 and discharges it to the atmosphere as blowing air in the 
direction of the paper sheet guiding plane. 
Instead of the drive bell 33 it is also conceivable to use a chain or a 
sprocket drive. 
In the embodiment of FIGS. 1 and 2, it is equally conceivable to use 
crossbars 36 with a rectangular section as illustrated in FIGS. 5 and 6, 
instead of the crossbars 22 with a circular section. The crossbars can 
also be matched to the aerodynamic requirements. 
As is illustrated in FIG. 6, in order to provide easier assembly, the 
configuration of the deflector plates, an example of which is shown in the 
second embodiment of FIGS. 3 and 4, can also be provided with the aid of 
two flanges 37 and 38 that are shown at an exaggerated distance apart. 
Carrier plates 39, 40 are attached at outer sides of the flanges 37 and 
38. The carrier plates 39, 40 have a circumferential region within which 
the deflector plates 18, 19 are mounted, as on the carrier plates 30, 31 
in FIG. 4. As is illustrated in FIG. 6, this configuration is conceivable 
both with the drive according to the first embodiment of FIGS. 1 and 2, 
and with the second embodiment of FIGS. 3 and 4 in which the flanges 30 
and 31 are mounted on the hollow shaft 32.