PRINTING PRESS, PREFERABLY FLEXOGRAPHIC PRINTING PRESS
The invention pertains to a printing press, preferably a
flexographic printing press, having a central impression drum
seated in bearings in a printing press frame and provided with a
drive, and at least one printing unit which consists of a driven
printing cylinder which can be pressed against the central
impression drum and of an inking or anilox roller which can be
pressed against the printing cylinder and which operates in
combination with a cleaning inking system such that the central
impression drum, the printing rollers and the anilox rollers
each have gears driving them on the same axle, the anilox roller
is provided with a special continuous running drive and such
that the printing cylinder gear can be coupled with the central
impression drum and the anilox roller gear can be coupled with
the printing cylinder gear by parallel displacement of the
printing cylinder and anilox roller, respectively.
A flexographic printing press of this type is known,
for example, from DE-PS 34 37 216. The drive of the central
impression drum and the drive of the printing cylinder and the
anilox roller of only one printing unit of the known printing
press are briefly described in the following based on Figure 7
of the drawing 5.
The shaft journals of the central impression drum 3,
indicated only by the dashed center line, are seated in bearings
in the side parts 1, 2 of the printing press frame. The bull
gear 4 is held by a key on the right shaft journal of the central
impression drum 3. The bull gear 4 is driven by the main drive
motor 5, which is an electric motor, via the drive pinion 6
and the intermediate gears 7 to 10, which form a corresponding
gear stage. The gears 8 and 9 are held by keys on a shaft 41,
indicated by a dashed line, which is also seated in bearings
in the printing press frame.
The printing cylinder 12 and the anilox roller 13 are seated
in bearings in the bearing blocks of slide carriages which can
be movably guided on brackets of the printing press frame, as
described in DE-PS 34 37 216. The printing cylinder gear 14 and
the anilox roller gear 15 are set on the right shaft journals
extending through the bearrng blocks of the printing cylinder 12
and the anilox roller 13, also shown only by dashed lines, where
the anilox roller gear 15 is seated in bearings on the anilox
roller shaft journal via a clutch 16. By moving the printing
cylinder slide carriage and the anilox roller slide carriage, the
gear teeth of the bull gear 4 and the printing cylinder gear 14,
as well as of the printing cylinder gear 14 and the anilox roller
gear 15, can be brought into and out of engagement. In this way,
the printing cylinder and anilox roller slide carriages carry out
a large-travel movement for replacing a printing cylinder and
only a short-travel movement for moving into the "print-off
position", in which the drum and cylinders are safely moved
apart, but their gear teeth are still loosely engaged with each
other.
Usually the anilox roller 13 continues to run in the
print-off position at a smaller rotational speed than during
the printing operation in order to prevent the printing ink from
drying up during relatively short interruptions of printing. This
continuous-run drive consists of the servomotor 17, which drives
the anilox roller 13 on the left shaft journal via the gear .
stage consisting of the gears 18, 19 and the clutch 20. This
continuous-run drive is possible because the anilox roller 13
can be turned in one direction due to the right clutch 16 even
when the anilox roller gear 15 is stopped. The continuous-run
drive does not prevent the drive of the anilox roller 13 via the
bull gear 4 and the printing cylinder gear 14 during normal
printing operation, because the drive gear 19 is also seated in
bearings via a clutch 20 on the left shaft journal of the anilox
roller 13.
For the printing press according to the invention, a
cleaning inking system, which was explained further in German
Patent Application No. 195 48 535.1 from December 22, 1995, is
pressed against the anilox roller 13.
This cleaning inking system consists, as is explained
briefly with the help of Fig. 8, of a doctor blade bracket 21,
consisting of a profile shaping rail, which can be adjusted on
the anilox roller 13. The rail of the doctor blade bracket 21 is
provided with a groove which forms the inside space of the ink
chamber. A bored hole 22 which supplies the printing ink opens
into this groove in the center area. Bored holes 23 and 24 which
carry off the printing ink are located in the lower end areas of
the groove. The front sides of the groove edges of the doctor
blade bracket are slanted away in the opposite direction in a
rooflike formation. On these front sides, doctor blades are
attached which can make trimming and/or rubbing contact with the
anilox roller 13. Seals are arranged on the sides of the doctor
blade bracket which seal off the inside space of the ink chamber
opposite the anilox roller 13. Doctor blade assemblies of this
sort are known, for example, from German Patent Application No.
195 16 223.3 and 195 16 224.2, to which reference is made for.
more precise description of the doctor blade assembly.
In the doctor blade assembly known from German Patent
Application No. 195 48 535.1, it is provided that during rinsing
for the purposes of cleaning the doctor blade assembly, the
anilox roller is driven one or more times in the opposite
rotational direction at a high rotational speed, i.e. at a
rotational speed which lies above the rotational speed during
the printing operation.
The problem of the invention is to create a printing press
of the type mentioned at the beginning in which the anilox roller
can be driven, both for the purpose of continued running at a
smaller continuous-run rotational speed than the operational
rotational speed, and for the purpose of cleaning the doctor
blade assembly, at an increased rotational speed, as opposed to
the operational rotational speed, in the reversed direction.
This problem is solved according to the invention in a
printing press of the type mentioned at the beginning, in that
the anilox roller can be coupled to the anilox roller gear via
a shiftable clutch and can be coupled by a second shiftable
clutch to a variable-speed and reversible anilox roller drive.
Since for the printing press according to the invention, the
anilox roller gear is connected to the shaft journal of the
anilox roller not by a free-wheel, but instead is connected to
it via a shiftable clutch, the anilox roller can be driven
independently of the printing press drive and also while the
printing press is standing still, via the anilox roller drive
in both rotational directions at any particular rotational speed,
thus not only at the lower continuous-run rotational speed, but
also at the higher rotational speed for cleaning.
In DE-PS 34 37 216, it was described that aligning the .
printing cylinders in proper registration with each other after
replacing them is a special problem for printing presses,
especially flexographic printing presses.
A further task of the invention thus consists in creating a
printing press, preferably a flexographic printing press, based
on the preamble of Claim 2, in which a simple proper registration
alignment of the printing cylinders is possible after their
replacement.
According to the invention, this purpose is achieved in
that the printing cylinder gear can only be coupled to the
central impression drum gear by a parallel displacement and
that the anilox roller is provided with a separate controllable,
variable-speed and reversible drive and can be coupled to the
printing cylinder gear by a gear.
For this embodiment of the printing press according to the
invention, the printing cylinders are only driven during the
printing operation by the bull gear, with which the printing
cylinder gears engage. The anilox roller is also driven via the
anilox roller drive in the printing operation such that the
rotational speed of the anilox roller can be controlled by a
computer. In order to make possible a simple and precise control
of the rotational speed, the drive motor for the anilox roller
drive is functionally made of a stepper motor.
During the printing operation/ the anilox roller can thus
be driven at the same circumferential speed as the printing
cylinder. Furthermore, it is also possible during the printing
operation to drive the anilox roller at a higher or lower
circumferential speed than that of the printing cylinder so
that the inking of the printing cylinder can be controlled in
this way.
During the print-off operation in which the anilox roller
thus does not contact the printing cylinder, it can be driven at
the desired smaller continuous-run rotational speed.
During the cleaning operation the anilox roller can be
driven in the reversed direction at the higher rotational speed,
i.e., for example, at a higher rotational speed than that of the
printing operation.
A special advantage of this embodiment of the invention is
that the anilox roller drive can be used, after a replacement of
the printing cylinders, in order to align the printing cylinders
of several printing units in proper registration. For this
purpose, the printing cylinder gears are provided with a mark,
for example, an identifying hole, by which the printing cylinder
can be rotated into an initial position opposite the printing
press frame. Starting from this initial position, the anilox
roller drives rotate the individual printing cylinders into
positions in which they are aligned in proper registration. In
this process, control of the individual stepper motors of the
anilox roller drives is done by a computer in which the initial
positions and the individual turning angles for aligning the
printing cylinders in their proper registration positions, are
stored.
Based on high computer performance, it is also possible to
carry out the required adjustments while the printing press is
running and, after aligning the individual printing cylinder
gears in proper registration, to bring them into the proper
angles and into precise engagement with the gear teeth of the
bull gear.
For the purpose of the proper registration adjustment of
the individual printing cylinders and/or the printing cylinder
gears, the printing cylinder gear is brought into engaged
coupling with an anilox roller gear. The coupling and uncoupling
of the anilox roller gear with the printing cylinder gear is
functionally done by the axial displacement of one of these
gears. Also, the computer makes certain in this that a proper
angle engaging of the gears occurs, without teeth knocking
against one another.
According to a third embodiment of the invention, it
is provided for a printing press according to the preamble
of Claim 2, that in turn the anilox roller is provided with a
separate controllable, variable-speed and reversible drive and
that the printing cylinder gear can be coupled only to the anilox
roller gear and the anilox roller gear can be detached from the
anilox roller by a shiftable clutch.
In this inventive refinement of the printing unit according
to the invention, the printing cylinder is no longer driven by
the bull gear which drives the central impression drum in the
printing operation, but instead via the anilox roller drive.
By this design, all advantages of the printing press can be
obtained by the second embodiment of the invention. In addition,
during the printing operation of the printing cylinder, a speed
can be imparted by the anilox roller drive which deviates from
the circumferential speed of the central impression drum so that,
based on the relative speed which can be obtained in the process,
unwinding errors of the web to be printed can be offset. By a
slower rotation of the printing cylinder the print image can
be extended in the circumferential direction, and by a higher
rotational speed, flattened.
Embodiment examples of the invention are described further
in the following based on the drawing. Shown in it are:
Figure 1: the drive of the central impression drum, and
of the printing cylinder and anilox roller, of one of several
printing units of a flexographic printing press, in a position
in which the slide carriages which hold the printing cylinder and
the anilox roller are carried off far enough that the printing
cylinder can be lifted out for the purpose of being replaced,
according to a first embodiment of the invention in schematic
representation;
Figure 2: a representation corresponding to Figure 1, in
which the printing cylinder and the anilox roller are located
in the print-on position;
Figure 3: a modification of the drive according to Figures 1
and 2 based on a second embodiment according to the invention, in
which the printing cylinder and anilox roller are located in the
print-off position;
Figure 4: a representation corresponding to Figure 3 in which
the printing cylinder gear has been brought out of engagement
with the gear teeth of the bull gear by parallel displacement of
the printing cylinder and, by axial displacement, into engagement
with the gear teeth of the anilox roller;
Figure 5: a representation, corresponding to Figure 1, of
the drive, according to a third embodiment of the invention, in
which the printing cylinder and anilox roller are located in the
print-on position;
Figure 6: a representation, corresponding to Figure 5, of
the drive in which the printing cylinder and anilox roller have
been carried away from the central impression cylinder by long-
travel movements;
Figure 7: a representation of a known drive corresponding
to Figure 1; and
Figure 8: a schematic perspective representation of a
central impression drum as well as a printing cylinder and an
anilox roller with a cleaning inking system.
Based on Figures 1 and 2, the drive of the central
impression cylinder and the printing cylinder as well as the
anilox roller of one of several printing units of a flexographic
printing press .is described according to the first embodiment of
the invention.
When the reference numbers in Figures 1 to 6 indicate the
same parts of a known flexographic printing press according to
Figure 7, these same reference numbers are used.
The drive according to Figures 1 and 2 is distinguished from
the drive described with the help of Figure 7 in that the anilox
roller gear 15 can be connected to the right shaft journal of the
anilox roller 13 by a shiftable clutch 20 and the motor 31 can be
connected to the pinion gear 18 of the gear stages 18, 19 by a
second shiftable clutch 32. Furthermore, a cleaning inking system
34 can be set on the anilox roller 13, as has been described with
the help of Figure 8.
In Figure 1, the drive is depicted in a position in which
the slide carriages holding the printing cylinder 12 and the
anilox roller 13 have been carried away by long-travel movements
far enough from the central impression drum 3 that the printing
cylinder gear no longer engages with the bull gear 4 and the
anilox roller gear 15 no longer engages with the printing
cylinder gear 14 so that the printing cylinder 12 can be lifted
out to be replaced. In the position depicted, the anilox roller
13 can be driven in reverse via the motor 31 during the washing
or cleaning operation, while the main drive is standing still,
at a rotational speed which is higher than the rotational speed
during the printing operation. For this purpose, the shiftable
clutch 32 is engaged by the central printing press control
so that the motor 31, which runs in both rotational directions,
drives the anilox roller 13 via the gear stage 18, 19 at the
desired rotational speed in the desired rotational direction.
Even if the gears 4, 14, 15 should still be loosely engaged
in the print-off position, the anilox roller 13 would be driven,
while the main drive is standing still, at a lower continuous-run
rotational speed, as well as a higher rotational speed during the
cleaning operation, since the anilox roller 13 is uncoupled from
the anilox roller gear 15 by the first shiftable clutch 30.
In the printing operation, the anilox roller gear 15 is
coupled onto the anilox roller 13 by the engagement of the
clutch 30 and the motor 31 is uncoupled by the release of the
clutch 32, which could also be arranged at another position.
The status of the drive during the printing operation can be
seen from Figure 2.
The motor 31 can be controlled by the central machine
control, for example a computer, and designed stronger according
to the higher requirements being placed on it.
In the second embodiment of the drive according to the
invention, which is now described with the help of Figure 3 and 4,
only the printing cylinder gear 14 can be brought into engagement
with the teeth of the bull gear 4 by parallel displacement of
the slide carriage holding the printing cylinder 12. The anilox
roller 13 is driven exclusively by the servomotor 40 via the gear
stage 18, 19 both during the printing operation and during the
continuous-run and cleaning operation.
The right shaft journal of the anilox roller 13 is provided
with a gear 41 which can be brought into engagement with the
teeth of the gear 41 only by axial displacement after uncoupling
the gears 4 and 14 and the corresponding moving together and/or
alignment of the printing cylinder 12 and the anilox roller 13,
so that the printing cylinder 12 can be aligned to the printing
cylinders of other printing units via the anilox roller drive
for presetting the registration after replacement.
Prior to start-up of the printing operation, the printing
cylinder gear 14 is again brought out of engagement with the gear
41 of the anilox roller by axial displacement, and the printing
cylinder is advanced into its printing position on the central
impression drum 3 so that the gear teeth 4, 14 come into
engagement in the proper way for the bearings.
From Figures 5 and 6, a third embodiment of the drive
according to the invention can be seen which is distinguished
from the embodiment examples according to Figures 3 and 4
essentially only in that even during the printing operation,
the drive of the printing cylinder 12 is performed by the
servomotor 50 for driving the anilox roller 13. The bull gear
51 is thus designed with a correspondingly smaller diameter
so that it no longer comes into engagement with the printing
cylinder gear 14 in the printing operation.
In order to be able to drive the anilox roller 13
independently of the printing cylinder 12 in the continuous-run
operation and in the cleaning operation, the anilox roller gear
15 can be uncoupled by a shiftable clutch 52 of the anilox
roller gear 15.
Furthermore, as can be seen from Figure 6, the printing
cylinder gear 14 can be brought into and out of engagement
with the anilox roller gear 14 [sic; 15] by corresponding axial
displacement on a spline shaft journal, which is necessary during
pre-setting in order to bring all printing cylinders into their
initial positions in which they are aligned in their rotational
angles to the machine frame based on identification marks.
The servomotors for the anilox roller drives are selected
such that they have suitable power for the demands placed on
them and that they can be controlled by the machine control for
adjusting the printing cylinders according to their angles.
The invention has been described above only on one printing
unit of a flexographic printing press. However, it applies
correspondingly to the additional printing units in multicolor
printing presses.
WE CLAIM:
1. Printing press, preferably a flexographlc printing press, having
a central impression drum seated in bearings in a printing
press frame and provided with a drive, and at least one printing
unit which consists of a driven printing cylinder which can be
pressed against the central impression drum and of an inking or
anilox roller which can be pressed against the printing cylinder
and which operates in combination with a cleaning inking system,
such that the central impression drum, the printing rollers and
the anilox rollers each have gears driving them on the same axle,
the anilox roller is provided with a special continuous running
drive and wherein the printing cylinder gear can be coupled with
the central impression drum and the anilox roller gear can be
coupled with the printing cylinder gear by parallel displacement
of the printing cylinder and anilox roller, respectively,
characterized in that the anilox roller can be coupled to
the anilox roller gear via a first shiftable clutch and can be
coupled by a second shiftable clutch to a variable-speed and
reversible anilox roller drive.
2. Printing press, preferably a flexographic printing
press, having a central impression drum seated in bearings in
a printing press frame and provided with a drive, and having
several printing units, each consisting of a driven printing
cylinder which can be pressed against the central impression drum
and of an inking or anilox roller which can be pressed against
the printing cylinder and which operates in combination with a
cleaning inking system wherein the central impression drum, the
printing rollers and the anilox rollers each have gears driving
them on the same axle, and the anilox roller is provided with a
special continuous running drive, characterized in that only
the printing cylinder gear can be coupled with the central
impression drum by parallel displacement and that the anilox
roller is provided with a separate, controllable, variable-speed
and reversible drive and can be coupled to the printing cylinder
gear by a gear.
3. Printing press according to Claim 2, characterized in
that the coupling and uncoupling of the anilox roller gear with
the printing cylinder gear is done by axial displacement of one
of these gears.
4. Printing press according to the generic concept of Claim
2, characterized in that the anilox roller is provided with a
separate controllable, variable-speed and reversible drive and
that the printing cylinder gear can only be coupled with the
anilox roller gear, and the anilox roller gear can be detached
from the anilox roller by a shiftable clutch.

A printing press consists of a central impression drum,
seated in bearings in a printing press frame and provided with
a drive, and at least one printing unit having a driven printing
cylinder which can be pressed against the central impression
drum and having an inking roller which can be pressed against
the printing cylinder and which operates in combination with a
cleaning inking system. The central impression drum, the printing
roller and the inking roller each have gears driving them on
the same axle. The anilox roller is provided with a special
continuous running drive. The printing cylinder gear can be
coupled with the central impression drum and the anilox roller
gear can be coupled with the printing cylinder gear by parallel
displacement of the printing cylinder and anilox roller,
respectively. In order to be able to drive the inking roller,
both for the purpose of continued running at a lower continuous-run
rotational speed than the operational rotational speed, and for the purpose
of cleaning the doctor blade assembly in the reversed direction at a higher
rotational speed than the operational rotational speed, the inking roller
can be coupled to the inking roller gear via a first shiftable clutch and
can be coupled by a second shiftable clutch to a variable-speed and
reversible inking roller drive.