Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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~EIDELBER~ A-72~ 13.06.1990
sa21050
DESCRIPTION
The invention concerns a device for charging the ink wells on
printing presses with an ink obtained by withdrawing the required
volumes of various primary colours stored in containers, mixing
them, and then discharging the mixed ink into the ink well.
Until now, printing inks for letter and rotary presses either had
to be delivered ready-mixed to the desired colour by thP ink
manufacturer or had to be mixed hefore the start of printing
outside the printing press. Rotary presses are often eguipped
with supply containers from which the ink can be automatically
drawn into the inking devices in order to obviate manual filling
of ink wells during operation.
When orders are process~d, the re~uired ink volume can usually
only be estimated. As a result, there are fre~uently remnants or
quantities of incorrectly mixed ink le~t over when the job is
completed. ~xcess quantities of ink mixed to a specific nuance
cannot be utilized and must be destroyed. Manual re-mixing is
difficult in spite of extensive experience and good colour
sensitivity and often results in ~ndesirable colour changes. In
addition, re-mixing interferas with the working process.
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In addition to the problems of correct ink supply, the entire ink
pathway within the printing press must b~ totally cleaned of ink
at the end of a print run to ensure that the colour of the next
print run is not compromised.
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This cleaning process is time~consuming and utilizes
hydrocarbons, the use of which is increasingly regarded as a
liability. The work is dirty and associated with exposing the
printers to cleaning agents that are often not entirely safe.
The purpose of this invention is to propose the ch~rging of ink
wells on pr.inting presses by a device that would always provide
continuous mi~ing of the ink to almost any desired nuance in the
required amount, including instances where less or more ink than
originally foreseen is utilized. The device would have to be
designed in such a way that it can be rapidly re set to another
colour.
To resolve this objective, the inventlon proposes that at least
one dosing device (2) be insertPd after every container (1); that
at l~ast two dosing devices (2) be connected to a mixer (6); that
every mixer (6) be connected to at least one ink well (10) for
discharge of the ready-mixed ink; and that the components of the
device that contain the ready-mixed ink consist of detachable,
exchangeable partsO
The invention turns away from the prepaxation of inks by mixing
outside the pxinting press in the preliminary stages of
production planning, by contrast proposing that the ink be mixed
continuously or in very small quantities on an ongoing basis from
the required primary colours in amounts that correspond to the
volume used.
This will resolve a problem that always arises in printing works
when inks are used that diverge from the primary colours. The
quantity of ink required for a print run can ne~er he exactly
estimated. The different surfaces of materials used for printing
often result in significant variances in the required ink volume.
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When orderinq pre~mixed inks one must either take into account
that large remnants may be left over, or risk running ~ut of the
appr~priate ink. Resulting ink remnants are stored and must very
often be discarded because the colour mixed for a specific job
cannot be reused. This becomes an environmental liability and
leads to ~inancial loss. Problems also arise when a print run
requires small amounts of a special colour: small volumes of such
special colours are usually not suppli~d by the ink manufacturers
and larger volum~s have to be ordered, again resulting in
significant remnants.
The de~ice here invented resolves these problems by allowing
special colours to be mixed from primary colours at a relatively
continuous rate during printing; by interrupting this mixing
process at the appropriate time towards the end of the print run,
practically no residual ink will re~ain. By skillful use of the
device it is possiblP to ~eep ink quantities in the ink wells
extremely l~w to facilitate optimal utilization without residue.
The quantity of ink mixed varies from about 0 to 100 grams per
minute, depending on printing form~t and manuscript.
At the end of a print run, i.e. when the printing press has been
stoppPd or when preparing the press for another print run with
other colours, the cleaning expenditure is minimal. Parts wetted
or filled with the mixed ink are exchanged, being designed as
exchangeable parts which allows them to be either discarded,
subjected to an environment-friendly recycling process, or put
through a cleaning process outside the machine where the use of
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HEIDELBERG A-728 13.06.1990
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cleaning agents is eliminated or minimized. Making these parts
exchangeable also reduces the down times.
At room temperature, inks used in offset printing are of a pasty
substance; their flow characteristics and thus also their
miscibility is significantly improved by heating. A particularly
efficient design of the invention therefore feature~ a pre-
heating area in conjunction with the mixer. The primary colour
containers, the tubing that leads to the mixer, or the mixer
itself can serve as pre heating area; or the entire device can be
installed in a housing which is completely he.atable. Raising the
temperature to 25 -40 C is sufficiant to ensure that mixing
results are considerably improved or more rapidly achieved. Since
heating the dye can lead to colour changes, e.g. through
evaporation of vola~ile components, the heating and mixing
process is best carried out in a hermetically sealed environment.
For this purpose the areas containing the heated ink are either
completely encased in a housing that protects the ink from all
air access, or the housing that covers these parts of the device
is filled with inert gas. These measures permit heating the ink
to 30 -50 C, thereby obtaining further improvement of the mixing
results. Since the different viscosity of heated ink compared to
cold ink can interfere with the printing process, it may be
appropriate to install a cooler between the mixer and the ink
wells in order to return the ink to room temperature.
Dosing of the primary colours is ef~ected by piston-type dosing
pumps (e.g. Orlita, Giessen), proportioning screw pumps or batch
controlled chamber charging devices. An economical solution is
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possible with manual or computer-controlled adjustable dosing and
filling cylinders. These are cylinders with pistons that are
filled through a three-way valve. ~y adjusting the thr~e-way
valve, the contents can be discharged in controlled doses in the
direction of the mixer. This permits simultaneous discharge of
content~ (ink) from all cylinders, which results in better mixing
in the mixer. It is advantageous to place the ink supply
containers under light pressure by means of an inert gas to
prevent any unwanted evaporation as a result of the suction
effect of the dosing device. An alternative is to equip each
container with a movable lid which is mainta1ned under light
pressure~ The inert gas cushion or mov~hle lid can ~lso be used
for the feed and dosing process; this will be further explained
below in connection with the description of application Pxamples.
Only parts that are wetted by job-specific inks, such as mixer,
conduits and, where applicable, tubes, are replaced as
exchangeable components after a colour change; these components
may include simple check valves or valves with minîmal opening
pressure. Unaffected are the supply conduits used continuously to
convey a specific colour from a primary colour container via the
; pump to the mixer. The Pxchangeable parts can naturally be either
cleaned or recycled if made e.g. of synthetic materials soluble
in weakly alkaline water, as currently available on the market.
.
It is appropriate to construct the mixer in such a way that a
minimum of residue remains when the ink is discharged after
mixing. This type of mixer design facilitates both recycling and
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cleaning of exchangeable components by minimizlng the residue of
ink after use. Corresponding construction designs will be
presented in conjunction with the descrip~ion of application
examples. These designs will in part suitable for recycling, in
part for cleaning; however, all can in princip~e b~ used for
either application.
It is possible to interconnect a large number of primary colour
containers with dosing devices, mixers and ink wells in such a
way that each inking device on a multi-colour press can be
supplied with every possible colour mix and the ink flow
controlled by adjustable valves. This system can be fed by a
program that controls dosing and ink ~upply so that the machine
always receives the necessary quantity of required special
colours. After the print run, the parts contaminated by the mixed
ink are simply exchanged. The nexk job using other special
colours can then be printed with a minimum o~ delay.
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It is also possible to connect each primary colour container to a
single dosing device and install a shunt equipped with valves
that do not affect the dosing between this dosing device and the
various mixers. In this way it is possible to service several
mixers from a single dosing device which can be switched from one
mixer to another. Another po~sibility is to supply several mixers
alternately with their required ink portions. The control valves
must not affect the dosing. Suitable for the purpose are e.g.
hall valves. The dosing devices may dispense the ink
volumetrically or gravimetrically.
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To facilitate complete di~charge of the ink from the mixer, the
internal space of the mixer should optimally consist of a cavity,
the volume of which is essentially variable from 0 up. As an
example, it can be designed a~ a ~queezable section of tubing
consisting of two mated, rectangular shPets of plastic foil heat-
sealed along the edges.
The mixer can also be designed as a cylinder surrounding a
movable, tightly sealed piston. In each aase there are connecting
nozæles on one side corresponding to the number of containers,
while at least one nozzle i5 located on the other side of the
mixer for connection to the intake mouthpiece on ~n ink well. In
this way almost uninterrupted discharge is achieved. In the case
of a cylindrical mixer, the connecting nozzles for the containers
may e.g. be located at the cylinder base, while the connecting
noæzle for the tube connection to the mouthpiece is located on
the piston.
If the mixer consists of a ~queezable tube section, this should
preferably be inserted into a holder designed so that it has a
support on one side, e.g. in the form of a platef with a movable
milling roller on the other side. The milling roller can be
mechanically moved back and forth e.g. by use of a pneumatic
cylinder. Alternatively, the support can be designed as a
circular se~ment with the milling roller operating by a swinging
circular motion.
With this type of design it is especially easy to install a
conveying roller to effect the discharge of mixed ink from the
mixer into the ink well. This roller moves along the same radius
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EIEIDELBERG A-728 13.06.1g90
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as the milling roller. e.g. on a ~rame extended backwards over
the milling roller's pivot point, which is then swivelled 1~0 to
effect discharge of the ink. The conveying roller must be
positioned on a longer radius on the frame, or the swivel axis of
the frame must he temporarily moved closer to the mixer while the
conveying roller works to discharge the ink. For thorough mixing,
the milling roller, in contrast to the conveying roller, must not
be allowed to compress the tube segment completely.
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Another po~sibility is to design tha milling roller with two
disks positioned at a given distance ~rom each other, so that
space is created between the disks wherein the ink can flow
contrary to the milling direction.
Depending on the consistency of the inks being mixed and the
quantities reguired, it may be appropriate to equip the milling
roller with a spiral ribbing to accomplish a lateral compression
in addition to compression in the direction of rotation. In this
design, the intake (connecting nozzles 5) and discharge
(connecting nozzle 7) are laterally displaced. Th~ pitch of the
spiral can be adapted to the length of the mixer in such a way
that the frame turns continuously, and the milling roller with
each revolution covers the mixer so ~hat its contents are forced
both in the direction of the milling roller and laterally. This
way the mixer contents are moved continuously, or in small
portions with each motion of the milling roller, from intake to
discharge. During this conveying process the ink is thoroughly
mixed by intensive milling; the spiral must be dimensioned in
accordance with the ink volume and the necessary m.ixing
intensity.
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Irrespective of the dssign of mixer and milling roller, it is
appropriate to separate the nozzles for connecting the containers
in the milling direction, and the nozzle that connects to the
mouthpiece, by a distance equivalent to the milling area. In this
way, thorough mixing is accomplished while emptying of the mixer
is also facilitated. When a mixer designed as a ~ube section is
used, the nozzles should preferably be located immediately at the
front end in a lateral surface area, so that the two side walls
are unimpeded by the nozzles and can lie totally flat against
each other with an internal volume of 0.
Particularly thorough mixing of the inks entering the mixer is
possible when a ferromagnetic body, especially a rod, is moved
without contact by means of a permanent magnet which is turned or
moved by a motor on the outside of the mixer. ~his causes
vigorous milling and squeezing of the ink and results in
excellent mixing. After use, the pin can very easily be removed
from the mixerr e.g. by simply pushing it through the mixer
membrane. In this way it is recoverable and reuseable.
A mixer may also consist of two rollers arranged side by side in
parallelO These contra-rotating rollers are fully or almost in
contact, the rotary motion converging at their top end. If inks
to be mixed are applied to the upper end of the rollers, they
will be thoroughly mixPd in the wedge area formed at the upper
end of the rollers. This results in wetting of the upper ends of
the rollers, but the contact or ~ery narrow gap between the
rollers nevertheless prevents the ink from passing through. The
ink is applied at one end of the roller pair and transported to
the other end e.g. by tilting of the rollers, in the process
being mixed and leaving the rollers at the other end as ready-
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~IDEL~ERG A-728 13.06.1990
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mixed ink. Instead of tilting the roller pair, the ink can also
be transported to the discharge point by intermeshing spiral
profiles. If such rollers are supported at one end only, and the
support designed so that the rollers are easily removable,
exchange of the rollers is easy and uncomplicated. Such rollers
can be cleaned after removal, or can be made of recyclable
plastic, or designed as disposablesO In any case the replacement
principle again reduces equipment down time when the pre~s is
switched from one colour to another~
.
Th~ rollers can also be covered by exchangeable tubing. It is
furthermore appropriate to cover the rollers by a housing
designed either so that it becomes completely ink~filled when the
inks for mixing are delivered, thus completely displacing the air
from ths mixer contents; or the housing may be filled with inert
gas. This housing should also be exchangeable. The mixer contents
delivered to the rollers can be pre-heated, or the rollers, the
housing, or both can be equipped with heaters.
Ultrasound can be used to augment the mixing by ~ttachment of a
relatively low-performance ultrasound head to the mixer. If the
inks are sufficiently thin, mixing by means of ultrasound alone
will suffice; in such cases tha appropriate temperature range is
e.g. between 30~ and 50 C.
It is not necessary for each batch first to be mixed and then
emptied into the ink wells. On the contrary, it is preferable to
work with continuous dosiny of the mixed ink until, towards the
end of a print run, the mixing tract needs to be emptied as
completely as possible. Since a certain pressure is applied ~y
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HEIDELBERG A-728 13.Q6.1990
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the dosing units, it is possible to adjust them for continuous
operation where they dispense amounts sufficiently small to allow
almost continuous delivery of the primary colours for mixing into
the mixer. This accomplishes a constant, or near constant,
discharge of mixed ink from the mixer and allows a constant
outflow of mixed ink from the mouthpiece.
At least on large presses, a development of the invention permits
the mouthpiece to slide along the ink well. This allows almost
any desired colour intensity to be applied over the length o~ the
ink well. In this manner, account is taken of situations where
the printing requirements call for specific areas to receive more
ink than others.
Continuous operation of the device is also possible with a
cylindrical mixer with an internal piston which is maintained at
a distance from the cylinder base and only allowed to move to the
base of the cylinder when the mixer is to be completely emptied
near the end of the print run. A mixer consisting of two rollers
equalizes a certain discontinuity of dosing and ensures that a
continuous amount of mixed ink leaves the mixer.
It is naturally feasible to connect several mixers to one
mouthpiPce, or several mixers and several mouthpieces, in order
to supply an exceptionally long ink well. Again, when several
~outhpieces are supplied from a single mixer, adjustable dosing
can be used to control the distribution to individual mouthpieces
and thereby to individual segments of the ink well.
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HEIDEI~ERG A-728 13 . 06. 1990
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At the beginning of a print run, the colour nuance required for
each in~ well is determined. It is assumed that the mixing
proportions ~o achieve the desired nuance from the pertinent
primary colours has been determined, e.g. by spectrophotometry or
by us ng data from a computer program. After checking that the
primary colours are available in adequate quantity within the
containers, the dosing devices are set accordingly or the
operating speed of drive motors commonly used on these dosing
devices controlled by an attached microprocessor. The appropriate
ink distribution along the length of the ink well is determined,
thereby indirectly providing direction for positioning of the
mouthpiece along the ink well. Alternatively, the ink well may be
divided into segments where a minimum level indicator in each
segment will signal an alarm that initiates immediate
replenishment of the ink supply.
At the beginning of the print run, a fresh mixer and fresh tubes
are inserted to make the equipment ready for operation. Before
starting the printing press, the ink wells are pre-filled
according to the required profile, or all sections filled to the
minimum ink supply level. The printing press can then be started.
During operation, ink is either supplied as programmed, or the
minimum level indicators will call up ink according to use.
At the end of the print run, the ink wells are run dry according
to experience, with all remnants having been drawn from the
mixers. After shutdown of the press, the ink wells are cleaned in
the usual manner, while each mixer and the tube connection to the
mouthpiece is emptied and exchanged. The mouthpiece is emptied
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HEIDELBERG A-728 13.06.1990
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and exchanged as required. These parts are cleaned, recycled or
discarded, with disposable mouthpieces best designed to consist
of a single valve that opens at a specific minimum pressure.
In the following, the forms of constructions shown in the
drawings will be explained in detail. The drawings represent:
Fig. 1 ~ schematic representation of the invention in a first
form of construction;
Fig. 2 A lateral view of a modified mixer;
Fig. 3 A schematic overview of the milling and conveying
device in the form of construction shown in figure 2;
Fig. 4 A cross section through another form of construction of
a mixer in accordance with the invention;
Fig~ 5 A schematic cross section o~ a dosing chamber for
dosing of ink in the mixer;
Fig. 6 An additional form of construction of a mixer similar
to that in Fig. 2;
Fig. 7 A mixer consisting of two rollers; and
Fig. $, 8a an additional dosing chamber.
In Figure 1, a form of construction of the invention is shown
schematically~ It is self-evident that appropriate mountings for
individual parts are present, nevertheless~ since it is possible
to select screw-on surfaces on existing printing presses, the
illustration is therefore in each case limited to the component
parts of the invention and not extended to include ancillary
parts such as mountings, tube clamps etc.
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~IDELsERG A-728 13.06.1990
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Primary colour containers 1 are installed at suitable points; in
Figure l a total of five containers are shown. ~mong primary
colours is included a binding agent that is part of the ink
recipe and also must be dosed in the prescribed amount~ One can
assume that 9 containers, including binding agent, suffice to mix
all possible colour nuances. Located immediately below the
container l are dosing devices 2, here shown only schematically.
These may consist e.g. of piston-type dosing pumps having
infinitely adjustable motors, or with the number of strokes being
pre-set in order to provide a given dosage. There are naturally
many suitable types of dosing and conveying devices. Below the
dosing devices 2 are stopcocks or valves 3 serving as main valves
to shut off the dosing devices 2 as well as the containers 1 from
the environment. The containers l are hermetically sealed and
under light pressure provided via a nitrogen or CO2 conduit, not
shown in detail, that opens into each container 1.
From each unit, a tube 4 leads from the container 1, the dosing
device 2 and the valve 3 to a connecting nozzle 5 on a mixer 6.
The primary colours (including binding agent) are supplied
through the tube 4 to the mixer 6 which is designed as a
squeezable section of tubing. Here it consists of a bottom foil
and a top ~oil which are heat-sealed to each other along the
edges. At one end the mixer ~ are located connecting nozzles 5
these are connected to the lower foil and are therefore turned
away from the viewer and located below the plane of the
projection. The same applies to a connecting nozzle 7 at the
other end of the mixer 6. Conne~ted to this nozzle is a tube 8
that conveys the mixed ink to a mouthpiece 9 which supplies the
inking device 10 with ink.
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}~IDELBERG A-728 13.06.1990
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The mixer 6 lies on a table (not shown) that has corresponding
cutouts for the connecting n~azzles 5 and 7. To prevent a reflux
of ink from the mixer into the tube 4, non-return val~es (not
illustrated) that moreover require a certain minimum pressure to
open, are integrated into the connecting noæzles 5. A similar
valve is located in the area of th~ mouthpiece 9.
When the colours have been mixed in the mixer 6, which will be
further described below, and after the ink has been discharged
from the mouthpiece 9, the ink still has to be distributed within
the inking device lO. For this purpose, a carriage 14 is provided
that moves on a guid~ bar 15 along the inking device lO. The
lateral motion is obtained by a screw 16 that is turned by means
o~ a drive motor 17 and this rotation achieves th mentioned
lateral motion via a nut (not shown) inside the carriage. The
travel of the carriage 14 to individual positions is controlled
either by a computer program or by dividing the inking device lO
into segments in which the ink requirement is signalled by means
of a minimum level indicator. Such minimum level indicators are
well known and therefore require no explanation at this point.
The device is ready for operation when the container 1 has been
adequately filled, the dosing devices 2 programmed, the valves 3
~- for the required colours opened, and the tube 4 completely filled
up to the conneoting nozzles 5. Continuing discharge of primary
colours into the mixer 6 results in it being slowly filled, with
clear traces of the various colours being immediately discernible
in th~. areas of the individual nozzles 5. Using
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HEIDEI.BERG A-728 13 . 06 . l990
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a milling roller 20, the mixer 6 is now repeatedly worked, mainly
transversely to its throughflow direction, by means of a back-
and-forth motion generated by a pneumatic cylinder 21 which
drives the milling roller 20. This results in viyorous and
adequate mixing of the individual primary colours and production
of the required colour nuance. The milling roller 20 is adjusted
so as not to compress the two foils that make up the mixer 6
completely, but to leave a certain passage during the milling in
order that the primary colours introduced into the mixer 6 only
mix, but are not extruded from the mixer 6.
Depending on the mode o~ operation or the desired operating
process, the gradual continued dosing of primary colours will
result in the mixer 6 reaching its maximum inflated volume. This
produces an overpressure in the tube 8 which is sufficient to
open the valve in the mouthpiece 9. Mixed ink is then discharged
corresponding to the dosed volume o~ primary colours.
Alternatively, the milling roller 20 can be lowered after a
completed mixing cycle so that the two foils of the mixer 6 are
compressed with no internal space remaining. This will result in
an almost complete extrusion of the mixed ink from the mixer 6.
Hence, when not lowered, the milling roller 20 produces a
continuous discharge of mixed ink from the mouthpiece 9; lowering
of the milling roller 20, results in intermittent emptying.
.
~ ~he nozzles 7 that connect the tube 8 to the mouthpiece 9 can
- naturally be placed to the left below the corner of the mixer 6
in order to accomplish as total a discharge of mixed ink as
possible from the mixer 6, while appropriately a small amount of
; mixed ink will remain, thus preventing unmixed colours from
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HEIDELBERG A~728 13~06.1990
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directly entering the tube ~ at the beginning of the mixing
cycle.
In Figures 2 and 3, a further development of the invented device
is shown wherein the milling roller 20 is moved in a different
manner. The mixer 6, in the form of the described tubing
segments, is not placed on a table but nestles along a support 27
designed as a circular segment. In the centre of the curvature, a
spindle 26 supports a rotatable frame 25, at one end of which the
milling roller 20 is located.
As clearly seen in Figure 3, the milling roller 20 can be made up
of individual disks 28. Between them, areas of smaller diameter
lPave channels free durin~ milling which allow the colours being
mixed to flow against the milling direction. Figure 2 indicates
that the frame 2~ during mixing can be moved back and forth by
means of a drive motor which is not shown in detail. In this way
the milling roller 20 in principle intermittently traverses the
mixer 6 along its entire length. This results in intensive mixing
of the primary colours contained in the mixer 6.
It is clearly seen in Figure 2 that the tubes 4 and 8 start from
the foil of the mixer (which is formed of two sheets of foil)
that faces the circle segment-shap~d support 27. Openings are
provided through the support 27 for the nozzles 5,7 and the tubes
4,8. In this manner it is again possible to compress both foils
to achieve an internal space with a volume that approximates 0.
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For the purpose of intermittent emptying of the mixer 6, the
frame 25 is swivelled 180 as indicated by the arrow, so that a
conveying roller 24 located at the opposite end of the frame 25
can traverse the mixer 6 from its upper end downward. This
ensures that its entire contents of mixed ink is discharged into
the tube 8 and thereby via the mouthpiece g to the inking device
10 (compare Fi~ure 1). The conveying roller should preferably
consist of a medium hard rubber roller; usually it is sufficient
for it to traverse the mixer once. ~he milling roller 20 is then
again applied against the support 27, and the next mixing cycle
can begin. A variation with a spiral-shaped milling roller has
already been described; it is not illustrated here.
It is self-evident that both the functions of mixing and
extrusion can be accomplished also with a solid roller, the
distance of which to the support 27 can be varied. The mixer 6 is
milled by maintaining the roller at a small distance; when the
distance is eliminated, extrusion results. This mode of operation
is also comparable to lowering of the milling roller 20 as shown
in the form of construction in Figure 1
.
In Figure 4 an additional form of construction is shown for a
mixer in accordance with the invention. It consists of a cylindPr
30 in which a piston 31 move~ tightly. The connecting nozzles 5
for the tubes 4 ~compare Figure 1) are located at the base of the
cylinder, while the piston 31 is equipped with a corresponding
connecting nozzle 7 for the tube 8. Between the piston 31 and the
cylinder base is a mixing disk 33. Its guide bar 36 is routed
hermetically through the piston 31. On the guide bar 36 there is
an oscillating device which in addition can be rotated as
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I~IDELRERG A-728 13.06.1990
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indicated, while the piston 31 can be mechanically operated or
supported by means of a piston rod 32. :
At the onset of colour mixing, primary colours are once again
present under light pressure at each connecting nozzle 5. The
mixing disk can lie flat against the inside of the piston 31,
whereby openings 34 in the mixing disk 33 smoothly overlap
elevations 35 on the piston 31. The unit formed by th~ mixing
disk 33 and the piston 31 can be brought to a position where it
rests on the cylinder base. As a re~ult of the continuous dosing
of primary colours at the beginning or preparation of a printing
run, this unit is forced back until it reaches e.g. the position
shown in Figure 4. At this point, the mixing disk 33 is moved
back and foxth by means of the gui.de bar 36, while the basic
; colours enclosed in the cylinder volume each time are forced
through the openings 34. This results in vigorous mixing. When
required, the mixing disk 33 can also be rotated in order to
achieve even more intensive mixing; for mixing of the entire
contents, the rotation can be adjusted in such a way that the
elevations 35 always engage with the openings 34.
; When ink is to be discharged from the mixer in accordance with
Figure 4, the piston 31 is moved against the cylinder base by
means of the piston rod 32, causing the mixed ink to discharge
from the nozzle 7 into the tube 8 (compare Figure 1). Reflux
through the nozzles 5 is again prevented by the non-return valve
(not shown) located in each nozzle 5. At this point the ink
chamber can optionally be totally evacuated, or a residue of
mixed ink retained in the mixer 6. If total evacuation i5
desired, the mixing disk 33 must first be brought to its original
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position where the openings 34 cover the elevations 35.
Naturally, this mixer also permits a continuous mode of
operation, characterized by the pistons 31 being merely
supported, and not moved, by the piston rods 32. The pressure
exerted by incoming ink then results in continuous evacuation
through the connecting nozzles 7, while the mixing disk 33 is
moved back and forth continuously or at intervals.
It can be clearly seen that the mixer 6 as designed in Figure 4
is particularly easy to clean, since it can be completely
dismantled and the dismantled components have no complicated
cavities or undercuts. Accordinglyl it can very easily be cleaned
by rinsing. This mixer is also suitable for reuse, which
nevertheless need not prolong the resetting time since the mixer
can be exchanged and cleaned outside the machine.
The mixer 6, the tube 8 and the mouthpiece 9 can be so designed
that they can be discarded upon colour change or after use. They
must then be made of an inexpensive synthetic material that can
be destroyed without detriment to the environment although
resistant to inks and solvents, while subject to no other
specific requirements. If it should happen that residual inks
from the preceding batch remain in the area of the non-return
valve at the end of the tubes 4, these tubes A must also be
exchanged, including their built-in non-return or check valves.
Since the pipes are extremely thin, both the ink loss and the
resulting waste is minimal.
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HEIDELBERG A-728 13 . 06 .1990
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In the event that leakage problems occur at the gasket between
the guide bar 36 and the piston 31 due to a film of dried ink, it
can be replaced by a sleeve or sock which will prevent these
problems. The same also applies to the gasket between the piston
31 and the cylinder 30.
dosing chamber 40 is shown in Figure 5 that could serve e.g. as
the dosing device 2 ~Figure 1~, i.e. in a number corresponding to
the n~mber of containers 1. For it to function, the inks in the
containers l must be lightly pressurized, either by a cushion of
inert gas or by a mechanically descending lid with a sliding
seal.
The dosing chamber 40 is separated into two chamber segments by a
divider 41, with the lower chamber segment featuring an
adjustment screw 42. The adjustment screw 42 is surrounded by a
metallic bellows ~3, attached on the one side to a disk 39
resting on the adjustment screw 42, and on the other side to the
interior of the chamber 40, its metallic construction providing
it with adequate pressure resistance.
A feed line 44 emanating from a ball valve 45 with an L-passage
leads to each chamber segment. Connected to the ball valv~ 45 is
a supply line 45, attached e.g. directly to a container l (Figure
1). In the same manner, each chamber segment is connected to one
o~ the discharge tubes 47, all of which are attached to a joint
ball valve 48. From this ball valve ~8, a tube 4 leads to the
mixer 6. This ball valve also has an L-passage and is
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HEIDELBERG A-728 13.06.1990
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mechanically joined with the above mentioned ball valve 45 to the
common switch, which, however, is not shown .in Figure 5.
Before the colours are added, the individual dosing amounts are
set with the adjusting screw 42. This determines the free passage
of the divider ~1 within the chamber 40, so that a specific
amount of ink leaves the chamber 40 with a single stroke along
its remaining length. Both segments of the chamber 40 are then
set so that the desired ink is added when each chamber segment
has discharged the volume equivalent to one stroke of the divider
41.
In Figure 5, the end of a dosing stroke is shown with the lower
chamber segment being emptied, i.e. the ink entering from the
supply line 46 has flowed into the upper chamber segment, moving
before it the divider 41 to the point where it touches the
~djustment screw 42. The ink present in the lower chamber segment
moves via the ball valve 4~ into the tube 4 and thus to the mixer
6.
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For the next dosing stroke, both ball valves are moved so that
the other line 4~ and 47, respectively, connects to the other
chamber segment of the chamber 40. ~he ink then ~lows into the
lower chamber segment, while the upper chamber segment empties
into the tube 4 via the discharge tube 47. Each of these dosing
chambers of the chamber 40 can deliver to a mixer of almost any
construction, with the inflowing colours being mixed in the
manner described, or in a manner to be described below.
Figure 6 serves to lllustrate how par=icularly efficient mixing
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HEIDE1BERG A-72~ 13 . 06.1990
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can be achieved within a mixer 6 by means of a ferromagnetic pin
50 which is moved inside the mixer 6 by a permanent magnet 51.
The permanent magnet 51 is moved back and forth around a c~ntral
point M, which at the same time is the central point of the
circular segment of the support 27, in a manner similar to the
motion of the frame 25 described in connection with the form of
construction shown in Figures 2 and 3. The pin 50, moved by means
of the permanent magnet 51, causes vigorous milling, squeezing
and consequently mixing of the inks contained in the mixer 6, so
that a few back and forth motions suffice to ensure satisfactGry
mixing of the colours.
Figure 6 shows schematically how spriny-loaded non-return valves
are installed in the nozzles 5 and 7. In other respects, this
form of construction is similar to that described in Figures 2
and 3. The mixer 6 thus consists of two superimposed sheets of
foil. Corresponding welds are indicated in Figure 6.
Mixing of the inks can be supported by an ultrasound head 53
attached to the back of the support. It causes vibrations in the
entire support 27 which are transmitted to the inks. If the inks
are heated until they are very thin, mixing by means of
ultrasound is in itself sufficient, and the ferromagnetic pin 50
and permanent magnet 51 can be dispensed with. All that is
required is then a conveying roller 24 (Figures 2 and 33 in order
to evacuate the mixer after mixing.
In the forms of construction shown in Figures 2 and 6, the ink
can naturally in principle also be moved transversely to the
mixing motion. This occurs when the inks enter at the one lateral
wheel of the support 27 and the mixed ink is discharged at the ~-
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MEIDELBERG A-728 13 . 06.1990
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other lateral wheel. The ink th~n moves towards, respectively
away from, the Dbserver.
Figure 7 shows a mixer 6 consisting of two rollers 60 and 61.
These rollers 60,61 are arranged in parallel side by side, almost
or actually in contact. The rollers 60,61 are contrarotating,
with the rotation converging at the top. The rollers 60,61 are
connected to the drlve by mountirlgs 6~,66 in such a way that they
can be simply removed for exchange purposes. A horizontal
inclination around the angle ensures that the inks introduced
at one end of the rollers in the area 62 slowly flow in the
direction o~ the arrow 63 to the other end of the rollers, in the
process becoming mixed and leaving the mixing device in the
direction of the arrow 64. By cham~ering or ridges at this end of
the rollers 60,61, the ink discharge is defined and contamination
of the back of the rollers prevented. Through the rotary motion
of the rollers, the ink introduced into area 62, consisting of at
least two primary colours, is intensively kneaded between the
rollers, while the distance between the rollers at their line of
contact 68 is zero or minimal, thus preventing the ink from
dripping through. Together with the viscosity of the ink, the
inclination of the rollers through the angle determines the
- flow v21Ocity. In this manner, optimal mixing results are
achi~ved with the appropriate roller length. The rollers can be
exchanged upon colour change and, if applicable, be cleaned or
covered with an exchangeable cover that is replaced when the
colour is changed.
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It is appropriate to enclose the rollers 60,61 in a housing,
which is not shown here. This housing should also be
exchangeable. To achieve better mixing results, the rollers ox
the housing or both can be heatable. It is also possible to
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E~EIDE:LBERG A-728 13 . 06 .1990
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suspend the rollers h~rizontally and equip them with a spiral
p~ofile, intermeshing along th9 line of contact, by mean~ of
which the ink is moved towards the discharge end (not shown).
Figures 8 and 8a show~a dosing device intended for dosing the
primary colours drawn from a container ~or delivery to the mixer.
This dosing device consists of a cylinde.r 70 inside which a
tightly sealed piston 71 moves. The piston 71 is driven by a rod
72 which leads into the cylinder 70. At the other end of the
cylinder 70, a connection 77 leads to a three-way valve 76 which
is connected to a container l (tube 74) and the mixer 6 (tube 75)
via its two other exits.
Figure 8a shows the position of the three-way valve in a
situation where the primary colour has been aspirated by the
piston 71 through the tubes 74 and 77 until the piston 71 reaches
a defined end position. The three-way valve then switches over
and in this position, as shown in Figure 8, leads the ink via the
pipe 75 to the mixer. The discharge volume is determined by the
stroXe and velocity of the piston.
Operation of the invented device is especially e~ficient when all
settings and manipulations as well as all moving sequences, such
as swivelli~g of the arm 25, activation of the conveying roller
24 and activation of the milling roller ~0, are controlled as
they recur. All movements can then at all times be controlled
e.g. via servo motors with adjustable stop switches to ensure
that defined return distances are covered. This allows a fully
automated mode of operation which can be reproduced at will by
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HEIDELBERG A-728 13.06.1990
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means of a specified program or according to an empirically
developed program, e.g. for repeat orders. ~o this end, the
adjusting screw 42 as shown in Figure 5 can, for instance, be
mechanically adjusted and controlled. The valves in Figure 1 are
also designed as magnetic valves, or similar, in order that the
selection of colours also can be programmed. The programmability
of the dosing units 2 has already been mentioned in the text
above. For the professional it poses no difficulty to provide
servo motors or very exact time-controlled valves that also
permit dosing at a constant pressure. Such dosing devices are in
common use, e.g. in ~uel injection equipment on automobiles.
Before a printing press can operate at full speed, the supply
devices and, where applicable, the interlinking e.g. of printed
sheets of carton, must be set up and adjusted. During this
process, a relatively large number of thoroughly usable copies
are generated which, although deriving from the adjustment run,
fully meet the quality requirements. Due to the slower operation
of the-machine, significantly less printing ink per time unit is
used at this stage than during subsequent full-speed operation.
Dosing must likewise be adjusted. It is therefore an advantage if
in these situations the speed of ink mixing can be adapted to the
- speed o* the printing press. This is especially simple if the
dosing devices consist of piston pumps or screw conveyors that
determine the dosing respectively by number of strokes or basic
speed. These can be adapted to the operating speed of the
machine, while a proportional speed contr^ller ensures that the
mixing speed is adjusted.
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