1. A method of operating a web-fed rotary printing press, particularly in the event of power failure, characterized in that an uninterrupted energy source is provided for selected components to prevent breakage of the web travelling in the press.

2. The method as claimed in claim 1, wherein the uninterrupted energy source is provided for folding, reel-stand, in-feed sections and folder super structure of the web-fed rotary printing press.

3. The method as claimed in any of the preceding claims, wherein the folding section comprises at least one unit each of folder, folder braking system and/or turner bar section.

4. The method as claimed in claim 2 or 3, wherein an uninterrupted energy source is provided for latching supply of drive contactor of the folders.

5. The method as claimed in any of the claims 2-4, wherein the folding section additionally comprises a web-severer provided with an uninterrupted energy source.

6. The method as claimed in claim 3, wherein the turner bar section comprises web-tension control rollers and/or air blowers.

7. The method as claimed in claim 6, wherein the turner bar section comprises drag rollers optionally provided with an uninterrupted energy source.

8. The method as claimed in any of the preceding claims, wherein in-feed section comprises a plurality of rollers;

9. The method as claimed in any of the preceding claims, wherein folder super structure comprises nipping roller(s) and their control system(s).

10. The method as claimed in claim 9, wherein the folder super structure comprises at least one unit of slitting roller, trolley and/or air blower.

11. The method as claimed in any of the preceding claims, wherein the printing unit(s) of the web-fed rotary printing press is provided with a quick exhaust port in one or more printing units for quickly retracting at least one blanket and/or impression cylinder in the event of power failure.

12. The method as claimed in any of the preceding claims, for the web-fed rotary printing press optionally comprising at least one web-severer or like device for the printing unit(s); 15 the method comprising the insertion of an additional solenoid valve powered by state/grid power into the web-severer.

13. The method as claimed in claim 12, wherein the web-severer comprises a severing cylinder, a valve for actuating the severing cylinder and a plurality of valves arranged according to a control logic for actuating the severing actuator.

14. The method as claimed in claim 12, wherein the additional solenoid valve is inserted into the pneumatic line preceding the valve responsible for actuating the severing cylinder.

15. The method as claimed in any of the preceding claims, wherein the web-fed rotary printing press additionally comprises an emergency stop circuit provided with an uninterrupted energy source.

16. The method as claimed in any of the preceding claims, wherein the web-fed rotary printing press additionally comprises a copy sensor provided with an uninterrupted energy source.

17. The method as claimed in any of the preceding claims, additionally comprising the steps of: initiating a controlled stop of the press so as to stop sections of the press provided with the uninterrupted energy source; providing power from an energy source like generator to the sections of the web-fed rotary printing press like printing units, which are not provided with an uninterrupted energy source; and, resuming operation of the press by initiating a controlled start for all sections of the press. e 18. The method as claimed in any of the preceding claims, wherein the uninterrupted energy source comprises an Uninterruptible Power Supply (UPS) selected from Standby, Standby-Ferro, Line interactive, Double conversion, Delta conversion UPS and the like.

19. An assembly for preventing web-breakage in a web-fed rotary printing press, particularly in the event of power failure, comprising an uninterrupted energy source for selected components of the web-fed rotary printing press.

20. The assembly as claimed in claim 19, wherein the uninterrupted energy source is provided for folding, reel-stand, in-feed and folder super structure sections of the web-fed rotary printing press. 16

21. The assembly as claimed in any of the claims 19 or 20, wherein the web-fed rotary printing press has a quick exhaust port in one or more printing units for quickly retracting at least one blanket and/or impression cylinder.

FIELD OF THE INVENTION
The present invention relates to a method of operating a rotary press, and more particularly
to a method of operating a rotary press in the event of a power failure so as to prevent web
breakage and equipments used for the same.
BACKGROUND OF THE INVENTION
Conventional rotary presses employ an integrated drive source comprising a plurality of
main motors provided on the printing section, folding section, unwinders and functional
groups like feeding and transfer rollers, forming rollers, cutting rollers and cooling
mechanisms. The numerous motors branch off from the longitudinal shaft via gears and
couplings. The gears further contain couplings gearwheels which make the system complex
_ and expensive.
Thus, in recent years, the "shaftless" rotary press has become much more popular because
of several advantages over the conventional presses with integrated drive source like a
shaft. In the shaftless units like the one disclosed in US Patent No. 6,408,748, several motors
are proVided to individually drive the various components of the press. Electrical
synchronous control is maintained so that the rotational speed and phase of the motors and
driven components can be matched with each other. Thus, the press becomes less
complicated and problems in a particular section can be isolated easily.
Modern high speed offset printing presses are characterized by their ability to maintain
newspaper web tension during acceleration, deceleration and steady state operation at
nearly 35000 revolutions an hour for cylinders of around 300 mm diameter in addition to its
various other attributes. Maintaining web tension is critical to smooth functioning of any
web-fed printing press because any steep variations can lead to a tear in the web.
Some of the latest presses have a safety feature wherein the web is automatically cut before
entering the printing towers and/or folders when conditions that could lead to web
breakage are detected. Some of these problems are drive error, power failure, web break,
excessive speed of the cylinders, etc. Thus, these presses are provided with a "web-severer"
which is usually actuated pneumatically. A web-severer prevents excess paper entry into the
printing towers from the paper feeding section. Another similar web-severer may also be
provided in the folding section. However, this safety feature is disadvantageous in
developing countries like India where grid power supply is irregular and frequent power
failures lead to inadvertent web-breaks.
2
A problem with the current methods of operating rotary presses is that whenever there is
power failure, it is invariably accompanied by web breaks in all reel stands and/or printing
units. This is because the driven components keep rotating due to inertia. The inertia of the
various driven components is different so their rates of deceleration are different. This leads
to difference in tension of the web traveling in different parts of the press, which causes
web breakage. Thus, the broken web wraps around the printing cylinders. The wrap around
can cause damage to the printing units and their inking units. In order to restart the press,
the web clinging to the cylinders has to be removed, which can take roughly 15 to 30
minutes. Also, the broken web has to be threaded again from reel stands to folder via the
printing tower and other sections, which leads to a loss of roughly 30 minutes. This problem
is very important in the newspaper sector where time is of essence. Thus, power failures
lead to huge downtimes which cause significant loss in productivity thereby hampering the
financial productivity of the press.
Since time is extremely important in the printing industry and in the newspaper industry in
particular, many presses are run by using generators as the primary power source. This is a
very costly proposition since the state/grid power is not used and the power supplied from
generators is relatively very expensive. Thus, the production time is not wasted due to nonreliance
on state/grid power but the cost of production per copy increases significantly.
Other methods to solve this problem have been disclosed in the prior arts, like providing
UPS (Uninterruptible Power Supply) in conjugation with state/grid power to feed the entire
printing press to either stop it in a controlled manner or keep the press running until
generator has been started. But this is a costly proposition because driven components like
the printing cylinders consume a large amount of power, so high capacity UPS has to be
installed. Moreover, there is no method suggested in the prior arts for preventing the webseverer(
s) from getting activated upon power failure. Thus, there is inadvertent web break
due to power failure, even though there is no problem in the web or printing press as such.
Systems for controlled stopping of the press as explained in the prior arts would be
ineffective since web tension can't be maintained once the web is broken.
SUMMARY OF THE INVENTION
The present invention aims to provide an economical method of running a printing press,
wherein state/grid supply can be used for the normal operation of the press. Further, the
method prevents web breakage during power failure and ensures that full operation of the
press is restored with minimal downtime.
In accordance with an embodiment of the current invention, is provided a method of
operating a web-fed rotary printing press, particularly in the event of power failure,
characterized in that an uninterrupted energy source is provided for selected components
3
to prevent breakage of the web travelling in the press. The other parts of the press like the
printing units run on state/grid power under normal conditions and on an energy source like
a generator whenever power fails. Thus, the cost of controlled stopping of press and
restarting it in the event of a power failure is greatly reduced.
In accordance with another embodiment of the invention, is provided a method of
operating a web-fed rotary printing press, particularly in the event of power failure, wherein
the uninterrupted energy source is provided for folding, reel-stand, in-feed sections and
folder super structure of the web-fed rotary printing press.
In accordance with yet another embodiment of the invention is provided a method of
operating a web-fed rotary printing press, particularly in the event of power failure, wherein
the folding section comprises at least one unit each of folder, folder braking system and/or
turner bar section; provided with an uninterrupted energy source.
In accordance with yet another embodiment of the invention is provided a method of
operating a web-fed rotary printing press, particularly in the event of power failure, wherein
an uninterrupted energy source is provided for latching supply of drive contactor of the
folders.
In accordance with yet another embodiment of the invention is provided a method of
operating a web-fed rotary printing press, particularly in the event of power failure, wherein
the folding section additionally comprises a web-severer provided with an uninterrupted
energy source.
In accordance with yet another embodiment of the invention is provided a method of
operating a web-fed rotary printing press, particularly in the event of power failure, wherein e the turner bar section comprises web-tension control rollers and/or air blowers. The air
blowers prevent the web from sticking to the rollers and web tension control rollers help
maintain tension in the web going towards the turner bars.
In accordance with yet another embodiment of the invention, the turner bar section
comprises drag rollers optionally provided with an uninterrupted energy source.
In accordance with yet another embodiment of the invention is provided a method of
operating a web-fed rotary printing press, particularly in the event of power failure, wherein
the in-feed section comprises a plurality of rollers; provided with an uninterrupted energy
source.
In accordance with yet another embodiment of the invention is provided a method of
operating a web-fed rotary printing press, particularly in the event of power failure, wherein
4
folder super structure comprises nipping roller(s) and their control system(s); provided with
an uninterrupted energy source.
In accordance with yet another embodiment of the invention is provided a method of
operating a web-fed rotary printing press, particularly in the event of power failure, wherein
the folder super structure electrical panels supply power to control slitting roller, air blowers
and trolley; provided with an uninterrupted energy source. The slitting roller slits the web
into two parts. The trolley constricts the motion of the web entering the folder super
structure. The role of air blowers is same as above.
In accordance with yet another embodiment of the invention, is provided a method of
operating a web-fed rotary printing press, particularly in the event of power failure, wherein
the web-fed rotary printing press comprises a quick exhaust port in one or more printing
units for quickly retracting at least one blanket and/or impression cylinder in the event of
power failure. The qUick exhaust port is sufficiently large so that retraction rates of the
printing cylinders are fast enough to ensure that the web doesn't stick or get pulled onto
them during power failure.
In accordance with yet another embodiment of the invention, is provided a method of
operating a web-fed rotary printing press, particularly in the event of power failure, wherein
the web-fed rotary press optionally comprises at least one web-severer or like device for the
printing unit(s); the method comprising the insertion of an additional solenoid valve
powered by state/grid power into the web-severer.
In accordance with yet another embodiment of the invention, an additional solenoid valve
powered by state/grid power is inserted into the web-severer for the printing unit. The
valve remains open as long as it gets state/grid power or a power source like a generator. If
C) no power is supplied to this solenoid valve, it closes, thereby blocking the pneumatic line for
the web-severer.
In accordance with yet another embodiment of the invention, the additional solenoid valve
is inserted into the pneumatic line preceding the valve responsible for actuating the
severing cylinder.
In accordance with yet another embodiment of the invention, the web-fed rotary printing
press additionally comprises an emergency stop circuit provided with an uninterrupted
energy source. The emergency stop circuit runs through the whole machine and switches off
power of all the parts of the machine on pressing the emergency stop button. It also helps in
maintaining the pneumatic controls of the machine for smooth stopping and starting of the
press.
5
In accordance with yet another embodiment of the invention, the uninterrupted energy
source comprises an Uninterruptible Power Supply (UPS) selected from Standby, StandbyFerro,
Line interactive, Double conversion, Delta conversion UPS and the like. Uninterrupted
energy source implies a source that can provide power with undisturbed continuity. Thus, a
diesel generator may also provide uninterrupted power for the purpose of the invention.
In accordance with yet another embodiment of the invention, the printing press is stopped
in a controlled way wherein the web tension is maintained in different sections of the press
when power fails. After the press has been stopped in a controlled manner, the printing can
be resumed in a few minutes once the components running on grid power are switched
over to a power source like a generator. Preventing the web from breaking helps in saving
the 30-45 minutes lost in removing the wrapped around paper from printing units and
threading paper from reel stands to folder via the printing tower and other sections.
In accordance with another embodiment of the invention, web tension is maintained upon
power failure because the components of the press crucial for maintaining web tension like
the reel stands, in-feed, folder section, folder super structure, turner bars, nipping rollers,
control section of the machine, etc. are always running on an uninterrupted energy source.
A normal stoppage of the press can be initiated thereafter to bring the web to a stop like in
normal press operation.
In accordance with yet another embodiment of the invention, whenever power fails, contact
of printing unit with the web is removed by a quick exhaust port. Thus, the tension can be
maintained as explained in the preceding paragraph to prevent breakage of the web.
Moreover, nothing is printing on the web/paper and no tension is exerted by printing units
on the web. The printing cylinders rotate freely till they stop when their inertial energy is
consumed completely.
In accordance with yet another embodiment of the invention, whenever power fails, the
additional solenoid valve inserted into the web-severer for the printing unit closes since it
does not get any power. This cuts off air supply to the pneumatic actuator of the webseverer
thereby preventing web break. Maintaining paper tension alone is not sufficient to
attain the objective of preventing web-breakage in presses where the web-severer has been
provided. This modification prevents the web-severer from actuating in case of power
failure but allows it to actuate in case of other problems. Thus, the web could be cut off
before its entry into the printing units when there are problems in the newspaper reels,
drive errors, problems in the web or some malfunction of machine, etc.
In accordance with an embodiment of the invention, there is provided an assembly for
preventing web-breakage in a web-fed rotary printing press, particularly in the event of
6
power failure, comprising an uninterrupted energy source for selected components of the
web-fed rotary printing press.
In accordance with another embodiment of the invention, the assembly for preventing webbreakage
in a web-fed rotary printing press, comprises an uninterrupted energy source
provided for folding, reel-stand, in-feed and folder super structure sections of the web-fed
rotary printing press.
In accordance with yet another embodiment of the invention, the assembly for preventing
web-breakage in a web-fed rotary printing press comprises a quick exhaust port in one or
more printing units for quickly retracting at least one blanket and/or impression cylinder.
The above mentioned advantages of the invention and its various embodiments will become
clearer by reading the trailing description in conjunction with the illustrations provided.
BRIEF DESCRIPTION OF THE DRAWINGS
The given figures are with reference to a particular embodiment related to a web-offset
printing press. The offset printing press is a complex machine and has been explained in a
simplified manner and parts of little significance for the purpose of elucidating the current
invention have been omitted or not explained in great detail. It is envisaged to keep the
terms used to represent the various components as general as possible, so that even if they
are not clear by their name, they can be understood from their function. The teachings and
methods of the invention are not limited to the present example and can be readily to other
types of printing presses as well.
C Fig. 1 is a schematic diagram illustrating the various sections of the press provided with UPS.
Fig. 2 is a schematic diagram illustrating the sub-distribution of the control section shown in Fig.
1.
Fig. 3 is a diagram showing a standard pneumatic mechanism for impression-off in the
printing units.
Fig. 4 is a diagram shOWing the modified pneumatic mechanism of the invention for quick
impression-off in the printing units.
Fig. 5 is a diagram showing the modification made to a standard web-severer for the
printing unit.
7
DETAILED DESCRIPTION OF THE INVENTION
Fig. 1 is a schematic diagram illustrating the various sections of the press provided with UPS.
The sections shown in the figure may be connected to UPS, generator or like device in the
normal operation, such that they are unaffected by failure in state/grid power. Power
supplied by the grid 101 is sent to a transformer 102, which supplies the power to UPS 103.
The UPS 103 supplies power to the various components of the press through its panel 104.
In the present embodiment, power lines supply to two folders namely Folder-A (111) and
Folder-B (112). Power lines also go to reel stand section 113, folder super structure 114 and
control section 115. It must be noted that 111-115 represent switches and 121-127 are the
drives which get power through these switches. Thus, power supplied to Folder-A goes to
Folder-A drives 121 and turner bar drives 122. Similarly, power sent to Folder-B goes to its
corresponding Folder-B drives 123 and turner bar drives 124. The power going to reel stand
section is sent to a plurality of reel stand drives 125 and in-feed drives 126. The folder super
structure 114 sends power to its nipping roller drives 127.
Fig. 2 shows the sub-distribution of control section i15 from Fig. 1. The control section
supplies power to Turner bar electrical panel 201, Folder super structure electrical panel
202, Folder A and B electrical panel 203, drive auxiliary supply 204 and Emergency stop
circuit supply 205.
Fig. 3 is a diagram showing a standard pneumatic mechanism for impression-off in the
printing units. The mechanism comprises solenoid valves 01, 02 and 03. Valve 03 stays open
when power is being supplied and closes when no power is being supplied. 22a and 23 are
flow regulating valves whereas 22b and 21 are exhaust valves. 11, 12 and 13 represent the
compressed air lines. The piston 31 is operated pneumatically to retract the blanket cylinder
when impression-off is required. Each printing unit has similar pneumatic mechanism for
every blanket cylinder.
Fig. 4 is a diagram showing the modified pneumatic mechanism of the invention for quick
impression-off in the printing units. In the present mechanism, flow regulating valve 22a and
exhaust valve 22b as shown in Fig. 3 are replaced by a quick exhaust port 22. The
compressed air line 12 may have to be resized in accordance with the size of quick exhaust
port 22. The other parts are the same as shown in Fig. 3.
Fig. 5 is a diagram showing the modification made to the web-severer for the printing unit
wherein an additional solenoid valve 500 has been inserted. The standard pneumatic
controls of the web-severer require compressed air from air supply 501 in order to function.
Two solenoid valves 502 and 503 are provided to detect conditions that could lead to web
break. The signal from these two valves is multiplied at an AND gate 504, which is a
8
pneumatic valve that needs an air signal from both of these valves in order to send an
output air signal for the web-severer to actuate or fire. A solenoid valve 506 is present
which is responsible for actuation of the web severing cylinder 507. The additional solenoid
valve 500 is inserted between AND gate 504 and pneumatic valve 506 and it has a coil 510
supplied with grid power.
The following description is with reference to a web-fed offset printing press which is
generally employed in the newspaper industry. It must be understood however, that the
invention is not restricted to the embodiments explained in the trailing description.
Teachings of the given embodiment of the invention can be readily applied to any rotary
printing press with or without suitable modifications. The invention in its broader aspects is
not limited to the specific details, representative devices and methods, and illustrative
examples shown and described in this section in connection with the embodiments and
methods. The invention according to its various aspects is particularly pointed out and
distinctly claimed in the attached claims read in view of this specification, and appropriate
equivalents.
Most of the web-fed offset printing presses have a plurality of drives to run the motors in
important components like reel stands, printing cylinders, folders, folder super structure, infeed,
turner bars, etc. The control scheme of the presses is such that during running or
stopping of the press, all the drives work in synchronized mode with folder drive working as
master. Centralized control is maintained and all the other drives follow the master.
In a web-fed printing press a continuous paper or web travels throughout the machine.
Tension in the web has to be maintained at each section of the press so that it doesn't get
stretched and/or break. In the present invention, we identified the critical components of
the press that are responsible for maintaining web tension within the press. These areas are
supplied with UPS at all times so that the web tension is maintained throughout the press
and the web doesn't break. Therefore, the press can be stopped in a controlled manner
after a failure in grid power 101.
In the present invention, no changes to the existing electrical connections have been made
except changing power source to UPS 103 for the components shown in Fig. 1 and Fig. 2.
UPS panel 104 distributes power from UPS 103 to the important components viz., folder
drives 121 and 123, turner bar drives 122 and 124, reel stand drives 125, in-feed drives 126,
and nipping roller drives 127, in addition to control section 115. Fig. 2 shows how the
control section power is further divided into turner bar electrical panels 201, folder super
structure electrical panel 202, folder A and B electrical panels 203, drive auxiliary supply 204
and emergency stop circuit supply 205. Thus, instead of supplying uninterrupted power to
the centralized control of the whole machine, power from UPS is supplied to the control
sections of only those components that playa role in maintaining web tension.
9
The power supplied through UPS 103 is responsible for functioning of the folder drives 121
and 123 and turner bars drives 122 and 124 of Folder-A and Folder-B respectively. The
folders are responsible for folding and cutting of printed paper in the form of the final
product, like newspaper. The folder has various sub-components like first folder, second
folder, third folder, a cutting device, etc. which are all supplied with uninterrupted power.
The turner bars are provided to change the direction of the web. In other cases, the parts of
the web are turned onto the same path through turner bars after being cut by a slitting
roller.
Power supplied from UPS 103 is sent to the reel stand section 113 comprising a plurality of
reel stand drives 125 and in-feed drives 126 throughout the press. A printing press has at
least one reel stand section for every printing unit. Reels containing the web or paper are
mounted on reel stands and this serves as the entry point of the web into the press. Since
printing in a continuous process, as in case of newspaper printing, an important function of
this area is to provide smooth transition from old reel to new reel commonly known as
splicing. The in-feed is the section just after the reel stands and plays very vital role in
maintaining web tension before its entry into the printing unit. Thus, the reel stand section
is provided with uninterrupted power so that drives are unaffected when grid power fails,
and do not stop abruptly which could cause web breaks in one or more reel stands.
The webs coming from the various printing units are combined at the folder super structure
114 before being fed to folder section. The folder super structure has several nipping rollers
run by nipping roller drives 127. The nipping rollers provide direction to the web and
remove any looseness.
Fig. 2 shows the various parts of the control section 115 of the machine viz. turner bar C electrical panel, folder super structure electrical panel, folder electrical panel, drive auxiliary
supply and emergency stop circuit supply. These panels are responsible for controlling their
associated drives and devices during startup, stoppage and normal operation.
The turner bar electrical panel (201) supplies power received from UPS 103 to control air
blowers and web tension control rollers. Some of the machines have holes for blowing air in
the turner bars. This creates a cushion between the web and the turning bars so as to
minimize the friction between the web and the turner bars. Web tension control rollers help
maintain tension in the web going towards the turner bars, so their speed has to be
controlled as well. The folder super structure electrical panels (202) supply power from UPS
103 for controlling slitting roller, air blowers and trolley. The slitting roller slits the web into
two parts. The trolley constricts the motion of the web entering the folder super structure.
The role of air blowers is same as above. Thus, these parts have to be stopped or started in a
controlled manner before production is resumed.
10
The folder electrical panel (203) supplies power to the web-severer for folding section, copy
sensor and folder pneumatic braking system. This web-severer needs uninterrupted power
so that it activates when conditions other than power failure arise, which can lead to web
break. The pneumatic braking system ensures controlled stopping of the motors in the
folder section whenever the folder drives have to be stopped. The copy sensor keeps a
count of the number of copies being produced.
The drive auxiliary supply (204) provides power for controlling nipping rollers, drag rollers
and latching supply of drive contactor of the folders. The latching supply of folder drive
contactor keeps the drive alive or ready at all times once the machine has been .turned on.
The emergency stop circuit (205) runs through the whole machine and switches off power of
all the parts of the machine on pressing the emergency stop button. This also helps in
maintaining the pneumatic controls of the machine for smooth stopping and starting of the
press, so uninterrupted power supply is essential for this part as well. It must be noted that
the above mentioned power distribution can be modified depending upon the drives or
devices present in the press and the panels used to supply them with uninterrupted power.
In the present example both sides of the web are printed at once in the so-called "blanketto-
blanket" printing process. In each printing unit, plates are mounted on the plate cylinders
and the images on the plates are transferred to the blanket cylinders. The impression from
the blanket cylinders is imposed on the web or paper when printing is started. The web
usually passes through a pair of blanket cylinders which exert pressure on each other as well
as the web. In this way, both sides of the web are printed in a single passage of the web
through a printing unit. Separate motors are used for each section of a printing unit
comprising of four printing couples of which two couples are responsible for printing on one
side and the other two are responsible for other side of the web. Each printing unit prints in
one color supplied to the plate cylinders via their respective inking units. Thus, in order to
print in 2 or more colors, separate printing units are provided for each color and the web
passes through each of these units before it goes for post-print operations like folding,
slitting, etc. The printing units are a major power consumer in any printing press and they
are supplied with grid power in the present invention.
Thus, in case of power failure, printing cylinders rotate freely until all of their inertial energy
is dissipated. But this has no impact on the web/paper as it is ensured that one or more
printing cylinders are retracted very quickly so that they don't have any contact with the
web. This is achieved through the modification shown in Fig. 4 wherein impression-off takes
place very fast in comparison to a standard scheme for impression-off shown in Fig. 3. In Fig.
3, two exhaust valves 21 and 22b and two flow regulating valves 22a and 23 are present.
Three solenoid valves 01, 02 and 03 are also present. Valve 03 closes and causes the blanket
cylinder to retract upon machine stoppage or power failure. Compressed air lines are shown
11
as 11, 12, and 13. In the modified mechanism, flow regulating valve 22a and exhaust valve
22b as shown in Fig. 3 are replaced by a quick exhaust port 22 in Fig. 4. The compressed air
line 12 may be resized accordingly but the other parts are the same as shown in Fig. 3.
Whenever power fails or is cut during a normal stoppage of the press, valve 03 closes.
Compressed air is quickly transferred from one chamber to the other in piston 31 with the
help of exhaust valve 21, quick exhaust port 22 and flow regulating valve 23. The quick
exhaust port 22 is of sufficiently large size so that retraction rates of the printing cylinders
are fast enough to ensure that the web doesn't stick or get pulled onto them during power
failure. The size of the quick exhaust port may vary from machine to machine depending
upon the cylinder port size. For example, an existing 6mm exhaust valve could be replaced
by a 12mm quick exhaust port so as to reduce the retraction time from 2 seconds to roughly
1 second.
In printing presses where a web-severer is provided before the entry of the web into the
printing towers, a modification is needed as shown by the encircled part in Fig. 5. In a known
mechanism, the web-severer has two solenoid valves 502 and 503 to detect conditions that
could lead to web break. Valve 502 sends an air signal when the speed of plate cylinders is
greater than a set value, say 5000 rev/hr. The set value is one after which the web might
wrap around the cylinders, so web needs to be cut-off or severed. Valve 503 sends an air
signal in case of web breaks, drive error or power failure. The signal from these two valves is
multiplied at an AND gate 504, which is a pneumatic valve that needs an air signal from both
of these valves in order to send an output air signal for the web-severer to actuate or fire.
Another solenoid valve 506 is present which is responsible for actuation of the web severing
cylinder 507. All the parts of the known mechanism are supplied with compressed air from
air supply 501. In the present invention, an additional solenoid valve 500 powered by grid
power supply is inserted into the existing web-severer. The solenoid valve has a coil 510
which remains energized and valve stays open when power is being supplied but gets
deenergized and air supply through the valve is blocked when no power is being supplied.
The additional solenoid valve is inserted between AND gate 504 and pneumatic valve 506,
such that during power failure, even though output air signal may be generated by the AND
gate, air supply is cut-off from solenoid valve 506 so that web severing cylinder 507 can't
actuate or fire. It must be noted that this is just one control logic for a web-severer and
other variations are possible. The important modification that is needed is that the solenoid
valve 500 should be inserted contiguously before the pneumatic valve responsible for
actuating the severing cylinder. Like web severing devices can have other inputs or control
logic for carrying out the severing action.
The structure of the printing press and the modifications made are clear from the preceding
paragraphs. When grid power fails, the various parts of the press responsible for
maintaining web tension are running on UPS and remain unaffected. The web tension is
maintained and thus the web remains intact. The web keeps circulating in the press as in its
12
normal operation, but nothing is printed on it due to the quick impression-off of the blanket
cylinders. The printing units are supplied with grid power, so their drives don't get any
power at the time when power fails. The valve 03 in Fig. 4 closes and compressed air moves
quickly from one chamber to the other in piston 31. The blanket cylinders retract, as they
would in a normal stoppage of the machine. However, due to the provision of a quick
exhaust port 22 in Fig. 4, the cylinders retract much faster than in the mechanism shown in
Fig. 3, and the web can't stick onto the cylinders thereby preventing wrap-around. The
cylinders keep rotating until their inertial energy is dissipated but they do not come in
contact with the web.
The parts of the machine supplied with power from UPS 103 keep running and web tension
is maintained from the inlet or reel stand section to the outlet or folder section. Thus, a
normal stoppage of the machine can be initiated and the drives are decelerated in a
controlled manner because the corresponding control sections are also provided power
from UPS 103 as explained earlier. The parts of the press like printing units which were on
grid power are switched over to a power source like generator. Once the web has been
stopped without any breakage, the machine can be started again since the parts which were
on grid power are getting power from the generator. Thus, a normal machine start can be
initiated within minutes of the power failure. Whenever grid power supply becomes
available, the parts of the press on generator can be switched back to grid power. Thus, the
press needn't use power from a device like generator all the time and this reduces the cost
of operating the press.
When grid power fails, the web-severer if present for the printing unit does not sever the
web because of the modification shown in Fig. 5. Solenoid valve 500 is powered with 24V
grid power supply 505, so its coil 510 gets deenergized when power fails. Thus, air supply
through valve 500 is blocked and the succeeding valve 506 responsible for actuating the
web severing cylinder 507 would not get any air signal to carry out web severing action in
response to grid power failure. However, once the components supplied with grid power
are switched over to power from a generator, the solenoid valve 500 will be open again. If
the AND gate 504 generates an output air signal for other problems like drive error, problem
in web, etc. web severing can take place.
A major advantage of the present invention is that the state/grid power can be utilized in
developing countries having irregular power supply, without compromising on the
productivity of the press. Thus, the cost per copy printed is significantly lower than units
operated using a power source like a generator throughout their operation. Also, printing
units which are a major consumer of power needn't be provided with UPS, which would
involve a large capital investment. The press can be stopped without breakage of the web
and subsequent web wrap around, so time is not wasted in removing wrapped around web
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and rethreading of web. Additionally, the web-severer(s), if present does not cause
inadvertent web breakage upon power failure.
The method of operating a web-offset printing press illustrated in the above mentioned
embodiment can be readily applied to other rotary presses as well after suitable
modifications. For instance, some parts may not be present or could be run without UPS.
Such variations are possible but could lead to some wastage of time. For instance, one may
only provide uninterrupted power supply to the reel stand and in-feed sections and allow
the web to run loose after the in-feed. This however would lead to loss of time in feeding
the web so released back into the machine. The web-severer modifications may also be
applied to any web-fed machine in general.

We Claim:
1. A method of operating a web-fed rotary printing press, particularly in the event of power
failure, characterized in that an uninterrupted energy source is provided for selected
components to prevent breakage of the web travelling in the press.
2. The method as claimed in claim 1, wherein the uninterrupted energy source is provided
for folding, reel-stand, in-feed sections and folder super structure of the web-fed rotary
printing press.
3. The method as claimed in any of the preceding claims, wherein the folding section
comprises at least one unit each of folder, folder braking system and/or turner bar section.
4. The method as claimed in claim 2 or 3, wherein an uninterrupted energy source is
provided for latching supply of drive contactor of the folders.
5. The method as claimed in any of the claims 2-4, wherein the folding section additionally
comprises a web-severer provided with an uninterrupted energy source.
6. The method as claimed in claim 3, wherein the turner bar section comprises web-tension
control rollers and/or air blowers.
7. The method as claimed in claim 6, wherein the turner bar section comprises drag rollers
optionally provided with an uninterrupted energy source.
8. The method as claimed in any of the preceding claims, wherein in-feed section comprises
a plurality of rollers;
9. The method as claimed in any of the preceding claims, wherein folder super structure
comprises nipping roller(s) and their control system(s).
10. The method as claimed in claim 9, wherein the folder super structure comprises at least
one unit of slitting roller, trolley and/or air blower.
11. The method as claimed in any of the preceding claims, wherein the printing unit(s) of the
web-fed rotary printing press is provided with a quick exhaust port in one or more printing
units for quickly retracting at least one blanket and/or impression cylinder in the event of
power failure.
12. The method as claimed in any of the preceding claims, for the web-fed rotary printing
press optionally comprising at least one web-severer or like device for the printing unit(s);
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the method comprising the insertion of an additional solenoid valve powered by state/grid
power into the web-severer.
13. The method as claimed in claim 12, wherein the web-severer comprises a severing
cylinder, a valve for actuating the severing cylinder and a plurality of valves arranged
according to a control logic for actuating the severing actuator.
14. The method as claimed in claim 12, wherein the additional solenoid valve is inserted into
the pneumatic line preceding the valve responsible for actuating the severing cylinder.
15. The method as claimed in any of the preceding claims, wherein the web-fed rotary
printing press additionally comprises an emergency stop circuit provided with an
uninterrupted energy source.
16. The method as claimed in any of the preceding claims, wherein the web-fed rotary
printing press additionally comprises a copy sensor provided with an uninterrupted energy
source.
17. The method as claimed in any of the preceding claims, additionally comprising the steps
of:
initiating a controlled stop of the press so as to stop sections of the press provided with the
uninterrupted energy source;
providing power from an energy source like generator to the sections of the web-fed rotary
printing press like printing units, which are not provided with an uninterrupted energy
source; and,
resuming operation of the press by initiating a controlled start for all sections of the press.
e 18. The method as claimed in any of the preceding claims, wherein the uninterrupted
energy source comprises an Uninterruptible Power Supply (UPS) selected from Standby,
Standby-Ferro, Line interactive, Double conversion, Delta conversion UPS and the like.
19. An assembly for preventing web-breakage in a web-fed rotary printing press, particularly
in the event of power failure, comprising an uninterrupted energy source for selected
components of the web-fed rotary printing press.
20. The assembly as claimed in claim 19, wherein the uninterrupted energy source is
provided for folding, reel-stand, in-feed and folder super structure sections of the web-fed
rotary printing press.
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21. The assembly as claimed in any of the claims 19 or 20, wherein the web-fed rotary
printing press has a quick exhaust port in one or more printing units for quickly retracting at
least one blanket and/or impression cylinder.