INKING UNIT

UNITE D'ENCRAGE

English Abstract

A cut down, column-free inking unit suitable for use in rotary
presses, comprising an ink fountain possessing a plate , a doctor
blade, a steel fountain cylinder and a steel ductor cylinder that
can be adjusted relative to the latter, an application cylinder,
a distributing cylinder and a transfer cylinder engaging with
application cylinder, a smoothing cylinder, a helical cylinder
serving the return of ink to the ink fountain, said helical
cylinder comprising worm grooves running from the inside to the
outside of such cylinder, as well as end disks that mesh with
outside rings of fountain cylinder. The design of fountain, ductor
and application cylinders with respect to circumference and
circumferential speed is such that the speed relationship existing
between all three cylinders is 1:0.2:2.5.

French Abstract

Cette invention concerne une unité d'encrage modifiée sans colonne adaptée aux presses rotatives, qui comprend un encrier équipé d'une plaque, d'un docteur, d'un cylindre d'encrier en acier et d'un cylindre preneur réglable par rapport à ce dernier, d'un cylindre applicateur, d'un cylindre distributeur et d'un cylindre de transfert en prise avec le cylindre applicateur, un cylindre de lissage et un cylindre à gorges hélicoïdales de renvoi de l'encre excédentaire vers l'encrier, ledit cylindre à gorges hélicoïdales ayant ses gorges en vis sans fin partant de son centre vers ses extrémités ainsi que des flasques qui engrènent avec les couronnes dentées du cylindre d'encrier. Le cylindre d'encrier, le cylindre preneur et le cylindre applicateur ont une circonférence et une vitesse périphérique calculées pour un rapport de vitesses s'établissant à 1:0.2:2.5.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A cut down inking unit without columns, comprising an ink
fountain (1), a steel fountain cylinder (2), a steel ductor
cylinder (3) that can be adjusted relative to said fountain
cylinder, an application cylinder (5), a distributing cylinder
(6), a transfer cylinder (7) that engages with fountain
cylinder (2), a smoothing cylinder (8) and an ink-return
device, whereby ductor cylinder (3), whose circumference is
less than the circumference of fountain cylinder (2), runs at
a circumferential speed that is from three to ten times less
than the circumferential speed of fountain cylinder (2),
wherein there is provided near ductor cylinder (3) for the
purpose of returning ink to the fountain is a helical cylinder
(9), which, comprising oppositely-running worm grooves running
from the inside to the outside as well as outer discs, engages
both with the outer rings of fountain cylinder (2) and with
squeegees located in the vicinity of the ink fountain, and the
arrangement of ductor cylinder (3) in relation to application
cylinder (5), whose circumference is considerably greater than
the circumference of ductor cylinder (3), comprises that the
gap existing between said application cylinder and said ductor
cylinder be virtually non-existent, and wherein the
circumferential speed of application cylinder (5) is two to
five times the circumferential speed of fountain cylinder (2).

2. Inking unit in accordance with Claim 1, wherein the ratio
of circumferential speeds of fountain cylinder (2), ductor
cylinder (3) and application cylinder (5) is 1:0.2:2.5.
3. Inking unit in accordance with Claim 1, whereby arranged
on downwardly-sloping ink fountain (1) and opposite fountain
cylinder (2) is a plate (10) on which is arranged a doctor
blade (11).
4. Inking unit in accordance with Claim 1, whereby
distributing cylinder (6) serves to transfer a secondary ink
stream to application cylinder (5).

Description

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The object of the present invention is a cut-down version of
an inking system without columnar adjustment capability
suitable for use in rotary presses used preferably to apply W
inks.
Conventional inking systems are unable to apply ink in uniform
thicknesses of between 1 and 2 m~ without the aid of
mechanically complex cylinder assemblies and ancillary
mechanisms.
The object of the present invention is thus the design of a
single column inking unit, which, when used in conjunction with
a rotary press, both prevents ink patterning and permits
application of ink films of precise thickness to the
printstock, without, even during longer press runs, requiring
either gap-adjusting screws or the number of cylinders that are
usually required to transfer an ink film of uniform thickness
to the impression cylinder.
In a broad aspect, the present invention relates to a cut down
inking unit without columns, comprising an ink fountain (1),
a steel fountain cylinder (2), a steel ductor cylinder (3) that
can be adjusted relative to said fountain cylinder, an
application cylinder (5), a distributing cylinder (6), a
transfer cylinder (7) that engages with fountain cylinder (2),

a smoothing cylinder (8) and an ink-return device, whereby
ductor cylinder (3), whose circumference is less than the
circumference of fountain cylinder (2), runs at a
circumferential speed that is from three to ten times less than
the circumferential speed of fountain cylinder (2), wherein
there is provided near ductor cylinder (3) for the purpose of
returning ink to the fountain is a helical cylinder (9), which,
comprising oppositely-running worm grooves running from the
inside to the outside as well as outer discs, engages both with
the outer rings of fountain cylinder (2) and with squeegees
located in the vicinity of the ink fountain, and the
arrangement of ductor cylinder (3) in relation to application
cylinder (5), whose circumference is considerably greater than
the circumference of ductor cylinder (3), comprises that the
lS gap existing between said application cylinder and said ductor
cylinder be virtually non-existent, and wherein the
circumferential speed of application cylinder (5) is two to
five times the circumferential speed of fountain cylinder (2).
The advantages afforded by the present invention centre around
a concept that permits the machine operator to calculate
backwards from the ink film thickness required in order to
arrive at the correct setting for a single control parameter,
namely the setting of the width of the distribution gap
existing between the fountain cylinder and the ductor cylinder.
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All of the other parameters, such as cylinder rotation speed,
etc., remain unchanged throughout the printing process.
Another advantage offered by the present invention is a
reduction in the number of bending points in the continuous ink
film, which in turn reduces the likelihood of flexural forces
acting at such points. Equally advantageous is the reduction
in the number of cylinders susceptible to thermal expansion
resulting from the heating of the flexing ink film. The
proposed arrangement moreover provides for more uniform ink
viscosity and improved system reliability.
The present invention will next be described by mens of an
embodiment example in the drawings, in which:
Figure 1 is a schematic view of the inking unit of the
present invention;
Figure 2 is a schematic illustrating the relationship
between Vl, V2, and V3 in Figure 1.
The proposed inking unit comprises an ink fountain 1, fountain
cylinder 2, a ductor cylinder 3 serving to transfer a primary
ink stream, the axis of ductor cylinder 3 being displaceable
for the purpose of changing the size of duct gap 4 relative to
fountain cylinder 2. Also provided are an application cylinder
5, a distributing cylinder 6 serving the transfer of a
2(a)
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201~99
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secondary ink stream, a transfer cylinder 7 and a smoothing
cylinder 8. Further provided is an ink re-circulating device,
comprising, in the present embodiment, a helically-grooved
cylinder 9 that acts to return to ink fountain 1 any excess ink
accumulating from the backflow over application cylinder 5.
The proposed inking unit operates conventionally by means of
cylinders, which rotate relative to each other in the same and
in opposite directions and at different speeds.
Ductor cylinder 3 runs in the same direction as the fountain
cylinder, but against the rotating direction of application
cylinder 5.
Fountain cylinder 2, which has preferably a diameter greater
than that of the ductor cylinder, rotates through the ink
fountain preferably at low speed in order to prevent ridging
of the ink on the outer cylindrical surface. The possibility
of ink ridging is further reduced by a downwardly-sloping ink
fountain 1 that is provided with a plate 10 on which a doctor
blade 11 is arranged.
Ductor cylinder 3 rotates preferably at a considerably slower
speed than the fountain cylinder, in order to prevent to the
greatest extent possible the occurrence of frictional heat on
oppositely-rotating application cylinder 5. The latter, whose
diameter is considerably greater than that of ductor cylinder

~,--
3, also rotates considerably faster than ductor cylinder 3.
This speed differential permits significant stretching of the
primary ink film transferred from the ductor cylinder to the
application cylinder.
Transfer cylinder 7 serves to transfer a secondary ink stream
from the fountain cylinder to distribution cylinder 6, which
in turn transfers ink to application cylinder 5.
Experience has shown that the optimum mixing propartions of the
two ink streams range between 85% to 15~ and 95% to 5%.
Before the speeds of the various cylinders can be set, it is
first necessary to be able to maintain duct gap 4 at a uniform
size. If steel is employed in the construction of the fountain
and ductor cylinders, the improved roundness coupled with a
lower thermal expansion coefficient permits the maintenance of
uniform gap sizes up to 15 m~.
It can, however, be advantageous to set the width of the duct
gap at a multiple of the original width, since fluctuations in
the width of such large gaps arising from imperfect cylinder
shape or thermal expansion of the cylinders is barely able to
affect the flow of ink.

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The character of the flow of ink to the cylinders can be
modified by the circumferential speed of fountain cylinder 2
in conjunction with a doctor blade 11, which can be adjusted
to handle maximum ink flow. By manipulating speed
differentials existing between fountain cylinder 2 and ductor
cylinder 3, the apportioning of the ink flows can be precisely
regulated and permit the greater portion of the ink to flow
from ductor cylinder 3 onto oppositely-turning application
cylinder 5. Application cylinder 5, whose turning speed is
greater than that of oppositely-running ductor cylinder 3, and
which is set beside the latter with practically no intervening
gap, takes up from the ductor cylinder the film of ink, which
stretches by virtue of the increase in speed.
The practically homogenous ink film produced by this process
is completely homogenized with the secondary ink stream
proceeding both from distributing cylinder 6, which
simultaneously smoothes out the ink film, and from following
smoothing cylinder 8. The resulting ink film is transferred
by means of application cylinder 5 to a not-illustrated
impression cylinder.
Tests have indicated that production of an effectively
homogenous ink film is best served if fountain cylinder 2,
ductor cylinder 3 and application cylinder 5 maintain the
following speed relationship: S1=l:S2=0.1-0.2:S3-2.0-2.5.

8 ~ ~
As Fig. 2 demonstrates, if the width of the duct gap is set at
100 m~, a layer of ink approx. 2.03 m~ thick will be applied
to the print stock. Reverse calculations demonstrate that
slight changes in the depth of the ink coat applied to the
print stock can be accomplished by effecting relatively large
adjustments to the width of the dispensing gap. In other
words, relatively gross adjustments made to the width of the
dispensing gap can result in rather fine changes in the depth
of ink applied to the surface of the print stock.
Backflow of ink not transferred from application cylinder 5 to
the impression cylinder is dramatically reduced by the
disposition of ductor cylinder 3 in relation to application
cylinder 5, whereby the virtual absence of an inter-cylinder
gap enables the oppositely-running ductor cylinder to scrape
any residual ink from application cylinders. In the present
embodiment, the scraped-off ink is, with the aid of helical
cylinder 9, which both runs oppositely to ductor cylinder 3 and
is provided with two helices or worm grooves running from the
inside to outside, picked up by an ink ridge built up preceding
the narrow gap separating application cylinder 5 from ductor
cylinder 3. The residual ink is then transferred to the
outside, where it is picked up by two outside rings of fountain
cylinder 2, the diameter of such rings exceeding that of
fountain cylinder 2, and then returned to the fountain with the

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aid of a set of squeegees. The proposed arrangement permits
the creation of a homogenous ink film without the disruptive
accumulation of residual ink.

Representative Drawing