Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Ink fountain blade for a printing machine
FIELD OF THE INVENTION
The present invention relates to a blade for an
ink fountain for a printing machine, the edge of which
blade is intended to maintain a determined thickness of
ink on an ink fountain roller, said blade being split
into several adjacent sectors that can be shifted so as
to vary the distance between the edge of the blade and
the circumference of the ink fountain roller.
The present invention also relates to an ink
fountain for a printing machine, said ink fountain
comprising an ink fountain roller, a bottom in the form
of a blade, the edge of which is close to the ink
fountain roller circumference, and two side walls in
contact with the bottom of the ink fountain and sealing
the sides of the ink fountain.
These blades and ink fountains are used mainly
in intaglio printing machines in which the amount of
ink applied to the ink fountain roller is great, so as
to adequately ink the intaglio cuts in the printing
plates.
PRIOR ART
Ink fountain blades and ink fountains of this
type are known in the state of the art. For example,
patent DD 110 632 discloses an ink fountain, the bottom
of which has a blade which is close to the
circumference of the ink fountain roller. In order to
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vary the distance between the edge of the blade and the
roller, that is to say the thickness of ink applied to
the roller, the blade is deformed elastically by screws
which press against the blade, on the other side
thereof with respect to the ink fountain roller.
The major disadvantage of this system lies in
the fact that the deformation of the blade does not
allow a constant thickness of ink to be applied. This
is because the profile of the deformed blade has,
roughly speaking, a rounded shape because the screws
press at a point location on the blade, which means
that the metering of the ink is thus inaccurate.
Another system is described in patent
application EP 0 600 435. In this system, the ink
fountain blade is formed of several adjacent bladelets
which can be elastically deformed in order to modify
the thickness of ink applied to the ink fountain
roller. To obtain this deformation, use is here too
made of a lever on the other side of the bladelets with
respect to the ink fountain roller in order to move
them closer to this roller and thus alter the distance
between the edge of each bladelet and the circumference
of the ink fountain roller and thus the thickness of
ink applied.
This system has several drawbacks, particularly
the fact that the deformation of the bladelets occurs
toward the ink fountain roller. Thus, in the event of
an error of manipulation, there is the risk that the
blade will come into contact with the roller and damage
it. The deformation of the blades also leads to fatigue
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in the material and this may create problems of premature wear.
SIJMMARY OF THE INVENTION
The purpose of the invention is to improve the known
systems.
More specifically, the purpose of the invention is to
propose a system which has a fine adjustment to allow a
constant thickness of ink to be applied to the ink fountain
roller, precisely, repeatably and without risk of damaging the
roller.
The invention is characterized by the fact that the
sectors forming the blade at the bottom of the ink fountain can
be moved in the plane of the blade parallel to one another.
The advantages afforded by the use of a blade split
into sectors according to the invention are many. Mention may,
in particular, be made of the fact that the movement of the
sectors is linear, which means that it is easier to control and
to measure. Specifically, any arbitrary point on a blade sector
according to the invention has the same movement, whereas in
the case of the bladelets known from the prior art, a precise
measurement of the movement could be made only on the actual
edge of each bladelet.
The invention provides a blade at the bottom of an
ink fountain for a printing machine, the blade being divided
into several sectors having respective edges for maintaining a
determined thickness of ink on an ink fountain roller, the
sectors being adjacent and shiftable to vary the distance
between the edge of each sector and the circumference of the
ink fountain roller, wherein the edge of each sector comprises
a reinforcement.
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The invention will be better understood from the
description of one embodiment thereof and from the figures
pertaining thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 diagrammatically shows an inking device
comprising two ink fountains;
Figure 2 shows a detailed view in part section of the
bottom of an ink fountain,
Figure 3 shows a view from above of part of the ink
fountain, and
Figure 4 depicts a dividing wall suitable for
mounting in an ink fountain including a blade according to the
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Depicted diagrammatically in Figure 1 is an inking
device with two superposed ink fountains, of the
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type used in intaglio printing machines. This device is
made up mainly of a mobile inking carriage 1,
comprising two superposed mounts 2, each mount 2 being
fitted with an ink fountain 3 formed of a bottom 4 and
of two side walls 5 collaborating with the ink fountain
roller 6. The bottom 4 is formed of a blade, the front
edge of which touches the ink fountain roller 6. To
illustrate one application of this ink fountain 3,
Figure 1 also diagrammatically depicts inking rollers 7
which, for example, ink impression plates (not
depicted) mounted on a plate cylinder 8.
The bottom 4 of the ink fountain is described
in detail with reference to Figures 2 and 3. This
bottom 4 is mounted on a transverse spindle 10 parallel
to the axis of the ink fountain roller 6 and pivots
about this spindle 10 toward the ink fountain roller 6
as the ink fountain is brought into operation. Blade
segments 11 are mounted on the bottom 4. These segments
11 are connected to the bottom 4 by transverse
slideways 13, 14 parallel to the spindle 10 supporting
the bottom 4 and which are themselves fixed to said
bottom 4 by means of screws 15 and 16. These transverse
slideways 13, 14 have the overall shape of a T, the top
of which is held in a corresponding slot 32, 33 cut in
the segments 11. All the segments 11 may thus be
mounted on the bottom 4 of the ink fountain by
introducing them sideways into the transverse slideways
13 and 14 and, once they are all in place, they can
then be moved at right angles to the spindle 10 of the
ink fountain by virtue of the clearance that there is
between the T-shaped top of the slideways 13, 14 and
the corresponding slot 32, 33 of the segments.
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At right angles to the slideways 13, 14, each
segment 11 has housings 19, 20, in each of which a
return spring 17, 18 is placed. These springs 17, 18,
which work in compression, serve to keep the segment 11
in the position in which the edge of the segments 11 is
closest to the ink fountain roller 6. This position may
thus be defined as being a reference position, and the
movement of the segments 11 in order to alter the
thickness of ink applied to the roller 6 is performed
by moving the sector 11 away from the roller 6.
The edge of the sector 11 is reinforced 12, for
example by a wafer of hard material such as metal or
ceramic which allows the life of each sector to be
lengthened considerably. This is because the inks used
have abrasive properties which wear the edge of the
blade away. However, in order to maintain application
of a precise thickness of ink to the roller 6, it is
necessary for the blade to be sharp-edged. The use of
reinforced sectors according to the present invention
thus makes it possible, on the one hand, to reduce the
wear on the edge and, on the other hand, for just one
sector to be changed in the event of premature wear,
rather than the entire blade, thus resulting in an
appreciable saving.
There is a specific system provided for
shifting each sector 11. This system comprises a cam 23
which, in Figure 2, is associated with a motor 21. The
cam 23 is placed in a corresponding slot 24 in the
sector 11 and mounted on the spindle 22 of the motor
21. The motor 21 itself is mounted iri the bottom of the
ink fountain 4 and is fixed in by screws 25 and 26. The
use of a motor as depicted in Figure 2 in particular
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allows the movement of the sectors 11 to be controlled
remotely. Thus, using an appropriate device, the
position of each sector can be adjusted constantly to
suit the quality of print produced, by combining the
system described with computerized control means, for
example. Of course, it is not necessary for the
movement of the cams 23 to be motorized and it is
possible to replace the motors 21 with a manual control
acting on each cam 23.
Figure 3 diagrammatically depicts six adjacent
sectors 11, 11' of an ink fountain. For a better
understanding of the invention, the middle sector,
referenced with the number 11, is depicted with an
exaggerated offset. This offset thus allows the
application over a determined width of a constant
thickness of ink which is different than the thickness
of ink applied by the adjacent sectors 11. According to
the size of the pattern which requires a determined
amount of ink, it is, of course, possible to shift more
than one sector 11 at a time, if the width of the
pattern exceeds the width of one sector 11.
Advantageously, a blade with sectors 11
according to the invention can be used in an ink
fountain comprising ink dividers. Such dividers are
used to separate the colors when the ink fountain is
used for multicolor printing. Patent EP 0 374 092, for
example, the content of which is incorporated in the
present application by reference, describes an ink
fountain including at least one such divider allowing
inking with at least two different colors.
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By attaching a divider directly to a sector 11,
there is obtained a modular system in which any
arbitrary sector as described hereinabove can be fitted
with a divider so that the assembly allows numerous
combinations.
Figure 4 diagrammatically depicts a divider 27
mounted directly on a sector 11 according to the
invention. The elements which are common to Figures 2
and 4 are identified with the same references. The
divider 27, known per se for example from patent
EP 0 374 092, comprises an intermediate plate 28 made
of plastic, for example nylatron, which is kept in
contact with the periphery of the ink fountain roller 6
by press means (not depicted) such as springs, so that
the contact remains leaktight.
If the divider 27 is not as wide as the segment
11 on which it is mounted, then the edge of the segment
11 on the same side as the ink fountain roller 6 needs
to be reinforced, for example using a wafer of hard
material 31 similar to the wafers 12 depicted in
Figures 2 and 3. A wafer 31 of this kind will in fact
be placed on each side of the intermediate plate 28. It
will thus be possible to shift the segment so as to
precisely adjust the thickness of ink applied in the
vicinity of the intermediate plate 28 while at the same
time maintaining sealed contact of this plate against
the ink fountain roller 6, by virtue of the press
means.
The system of segments 11 may also be used
advantageously for mounting the ink fountain side walls
5, these being placed on the two end segments of the
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blade at the bottom 4 of the ink fountain. Such side
walls are described in patent EP 0 374 092 mentioned
hereinabove, and also in Swiss patent application No.
105/99 filed on January 20, 1999 and not published at
the present time, the content of which is incorporated
in the present application by reference.
The embodiments of the invention are described
by way of example and variations are possible within
the scope of the claimed protection. For example, the
number of slideways 13, 14 may be increased. It is also
possible to envisage return means other than the
springs 17, 18. Likewise, use may be made of another
system equivalent to the system of cams used for moving
the segments 11.
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