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EP 0 178 112 B1 |
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EUROPEAN PATENT SPECIFICATION |
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Mention of the grant of the patent: |
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17.01.1990 Bulletin 1990/03 |
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Date of filing: 01.10.1985 |
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Inking and doctoring process and arrangement for a pad printing machine
Vorrichtung und Verfahren zum Einfärben in eine Tampondruckmaschine
Procédé et dispositif d'encrage dans une machine pour imprimer au tampon
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Designated Contracting States: |
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AT BE CH DE FR GB IT LI LU NL SE |
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Priority: |
04.10.1984 JP 208727/84
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Date of publication of application: |
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16.04.1986 Bulletin 1986/16 |
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Proprietor: DAIICHI MACHINERY SERVICE CO. LTD. |
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Tokyo (JP) |
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Inventor: |
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- Tobita, Joji
Kawaguchi-shi
Saitama-ken (JP)
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Representative: Gillam, Francis Cyril et al |
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SANDERSON & CO.
European Patent Attorneys
34, East Stockwell Street Colchester
Essex CO1 1ST Colchester
Essex CO1 1ST (GB) |
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References cited: :
EP-A- 0 012 934
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DE-A- 2 205 430
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| Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
|
[0001] This invention relates to a process and an arrangement for inking and doctoring a
printing plate for use in a pad printing machine. In particular, the invention concerns
a process and arrangement where ink is applied to a desing provided on a printing
plate, the plate is doctored by a suitable doctor blade and then ink is picked up
from recessed parts of the printing plate by means of a pad provided as a part of
the printing machine.
[0002] In known pad printing machines, a printing plate having a design or plattern etched
therein usually is mounted within an ink tray, a doctor blade being arranged to scrape
excess ink off the surface of the plate and so to leave ink in the recessed parts
of the plate.
[0003] The prior arrangements generally have been of one of two types. In one, the ink tray
is fixed while the doctor blade and so on are arranged to be movable horizontally
over the surface of the plate. In the other, the doctor blade and so on are fixed,
and the ink tray is moved horizontally below the blade. These arrangements both require
the ink tray to be open-topped, so that thinners or other components of the ink evaporate
over a period of time. Consequently, if printing is to be continued for some time,
the ink must appropriately be replenished for example by means of an automatic thinners
adding device. Also, foreign matter may easily fall into the ink tray and so contaminate
the ink.
[0004] In an attempt to overcome the difficulties of an open ink tray, there has been a
proposal (described for instance in DE-A 2 205 430) to contain the ink within an open-bottomed
pot which bears on the printing plate, to permit ink to be applied to the plate. Such
a pot may be closed on its upper part to prevent ink contamination. This arrangement
however requires a very high degree of flatness for the printing plate to prevent
ink leakage from the pot and so is applicable mainly to printing plates having a relatively
small printing area.
[0005] A further problem with the known arrangement is that the two steps, of doctoring
the printing plate and of reapplying the ink, are both necessary on each cycle of
the printing operation and so it has been difficult to accomplish continuous printing
operation at a relatively high speed.
[0006] It is a principal object of the present invention at least to reduce the problems
discussed above of the known inking and doctoring and arrangements in pad printing
machines.
[0007] According to one aspect of this invention, there is provided an inking and doctoring
process for a pad printing machine in which ink is applied to a design provided on
a substantially flat printing plate, the plate is then doctored by means of a doctor
blade and then ink is picked up from the recessed parts of the printing plate by means
of a pad provided as a part of the printing machine while the doctor blade is at least
substantially in a state of rest, which process is characterised by the performance
of a doctoring step in which the printing plate and the doctor blade are rotated relatively
to effect the doctoring of the plate, before the printing machine pad picks up ink
from the printing plate.
[0008] The relative rotation between the printing plate and the doctor blade either may
be performed stepwise with the rotation each time being in the same sense, or may
be performed in a back-and-forth manner. In both cases, the doctor blade may be. maintained
fixed whilst the printing plate is rotated, or the printing plate may be maintained
stationary whilst the doctor blade is moved rotatively in a back-and-forth manner.
[0009] An advantage of the process of this invention is that re-inking using a separately
movable ink applicator may not be necessary on each printing cycle. This allows the
process to be performed at a relatively high speed. Moreover, the printing plate may
have more than one printing area which areas are successively doctored, so permitting
printing at a high rate.
[0010] According to another aspect of this invention, there is provided an inking and doctoring
arrangement for a pad printing machine including an ink tray in which is mounted a
substantially flat printing plate, a doctor blade arranged to scrape ink off the upper
surface of the printing plate and an ink tray cover which is disposed over the ink
tray to minimise evaporation of ink components, characterised in that there is provided
a drive device adapted to cause relative rotational movement in the horizontal plane
between the printing plate and the doctor blade to effect doctoring of the plate.
[0011] In this arrangement, the portion of the ink tray containing the ink is kept almost
completely closed and it is enough that only a part of the ink tray is left open to
allow a printing pad to descend through the open part to pick up ink in the design
to be printed, so that components of the ink (such as thinners) can largely be prevented
from evaporating. Moreover, the probability of foreign matter entering the ink is
much reduced.
[0012] For a case where the relative rotation is performed stepwise and in the same sense,
it is preferred for the doctor blade to be shaped to define a closed area (such as
a circular area) within which area a design on the printing plate to be printed may
lie, doctoring taking place as that design moves under the blade. Alternatively, for
a case where the relative rotation is performed in a back-and-forth manner, two doctor
blades may be provided, arranged alternately to contact the printing plate, depending
upon the sense of relative movement between the doctor blades and the printing plate.
[0013] By way of example only, certain specific embodiments of the invention will now be
described in detail with reference to the drawings, in which:
Figure 1 is a side view showing a conventional ink- ing/doctoring arrangement of a
printing press;
Figure 2 is a side view showing an ink pot and a printing plate arranged in accordance
with the prior art;
Figures 3(a) and 3(b) are schematic illustrations showing in outline an arrangement
according to this invention;
Figures 4(a) and 4(b) are schematic illustrations of an ink tray and a plate arranged
according to one embodiment of this invention;
Figures 5(a) and 5(b) are illustrations of a cylindrical doctor blade holder as used
in the arrangement of Figure 4;
Figures 6(a) and 6(b) are illustrations of a support for the doctor blade holder;
Figures 7(a) and 7(b) are schematic illustrations of a doctor part arranged in the
case where a forward-and- backward rotation table is employed, according to a second
embodiment of this invention; and
Figure 8 is an illustration of a printing process as performed by an arrangement of
the invention.
[0014] Generally, as shown in Figure 1 of the accompanying drawings, known inking part of
a pad printing machine comprises an ink tray 1 in which is placed a printing plate
2, a doctor blade 3 being arranged to scrape ink off the surface of the plate and
an ink return device 4 being arranged to reapply ink to the whole surface of the plate.
[0015] The inking part may be arranged in one of two ways. In one, the ink tray is fixed
while the doctor blade and so on are arranged to be horizontally movable. In the other,
the ink tray is arranged to be horizontally movable while the doctor blade and so
on are stationary. In either case, the ink is scraped off the plate by means of the
doctor blade 3 as the doctor blade 3 moves to the right (as viewed in Figure 1) relative
to the ink tray and then is returned or reapplied to the surface of the plate when
the ink return device 4 moves to the left. As mentioned above, this inking part has
the disadvantage that thinners for the ink evaporates in time, so necessitating the
use of an automatic thinners adding device. In addition to that, since the two processes
of doctoring and ink return are absolutely necessary, it has been difficult to accomplish
continuous printing at a high speed.
[0016] Figure 2 shows a known alternative doctoring arrangement, to prevent the evaporation
of the thinners. Here, the ink is kept within a completely closed ink pot 5 disposed
over the plate 2. This arrangement can however be used only with very flat printing
plates and so is practical only with small print areas.
[0017] Referring now to Figures 3(a) and 3(b), showing schematically an arrangement of this
invention, a base plate 10 is suitably mounted on the body of a pad printing machine
(not shown). An ink tray cover 12 is provided with an ink supply port 6 and a doctor
blade insertion port 12-1 and is secured to the upper part of an ink tray 13 by means
of carrying arms 7 which are pivotally attached to respective supports 9. Each of
the carrying arms 7 is fixed in a predetermined position by a screw 8 and is arranged
to be slidable vertically and rotatable about a vertical axis to facilitate removal
and attachment of the ink tray cover 12. The ink tray 13 is mounted on an index drive
11 and is arranged to be rotationally advanced stepwise. In the contact region between
the ink tray 13 and the ink tray cover 12 is arranged a ringshaped low-friction packing
material 14.
[0018] Referring to Figure 4(b), a plate 18 is fixed in position by means of screws 17 within
the ink tray 13. A thin-band doctor blade 16 is mounted on a doctor blade holder 20
and is arranged to come into contact with the upper surface of the plate 18 through
the doctor blade insertion port 12-1. The blade 16 is secured to the ink tray cover
12 by means of doctor blade holder supports 19.
[0019] An ink guide 15 is attached to the lower surface of the ink tray cover 12 and is
thus arranged to bring ink back to the middle part of the ink tray when the ink tray
rotates. A clearance of about 0.5 to 1.0 mm is provided between the lower edge of
the ink guide and the upper surface of the plate 18.
[0020] Figures 5(a) and (b) show a doctor blade holder 20 which has a cylindrical shape,
but the doctor blade holder 20 may of course have a square shape or may have in combination
a linear blade and a cylindrical blade formed to prevent the evaporation of thinners
from the ink, as shown in Figure 7. A sealing plate 21, made of a resilient plastic
material, is attached to the cylindrical side face of the doctor blade holder 20.
With the sealing plate 21 thus arranged, thinner is prevented from evaporating from
between the ink tray cover 12 and the doctor blade holder.
[0021] Referring to Figures 6(a) and (b) pins 22, provided at both ends of the doctor blade
holder, are received in and connected to the doctor blade holder support 19. In order
to enable the doctor blade to move freely in contact with the upper surface of the
plate, a rose joint 23 or the like is preferably used to receive the pins 22.
[0022] The ink feeding and doctoring operation of the arrangement described above is as
follows.
[0023] Referring to Figure 4(a), the surface of the plate 18 with the exception of a part
A which is encompassed by the doctor blade holder is completely covered with ink.
Therefore, under this condition, design parts B, C and D are in the same state as
when they have ink reapplied to them by an ink returning process. When the index device
is shifted through one step, the design part B comes to the printing position. At
that time, the doctor blade is held in contact with the plate, and so redundant amounts
of ink are scraped off the design part B, leaving ink only in the recessed parts thereof.
[0024] With the arrangement of this embodiment connected to a printing machine, the pad
of the machine then begins to descend on the design part B, and then ascends again.
The other design parts C, D and A remain covered with the ink during this. After that,
the index arrangement is moved one step further, to bring the design part C to the
printing position, and the pad which has transferred the ink to matter to be printed,
again comes on to the design part C of the plate. These processes are thus repeated
in carrying out a printing operation.
[0025] In the foregoing description of the specific embodiment, the index drive is arranged
to have four steps. However, the number of steps is not limited to four.
[0026] In another embodiment of the invention, a rotary stepwise feeding device is disposed
to be associated with the doctor; and, after the ink on the design part A of a plate
which is arranged to be stationary is picked up by the pad, the doctor is arranged
to come back, being caused to complete one turn by the rotary feeding device. The
printing operation also can be carried out in the same manner in this case. Two units
of the above-stated rotary stepwise feeding device may be arranged, one associated
with the doctor and the other with the printing plate.
[0027] The index drive 11 shown in Figure 3(b) may be replaced with a suitable back-and-forth
rotating device such as an air roll-back table. In that event, the doctor part should
be modified as shown in Figures 7(a) and (b). Referring to those Figures, a cylindrical
part 27 is arranged either to rest on the plate 18 by its own weight or to be carried
by the ink tray cover 12 to leave a clearance of about 0.5 mm between the plate and
the cylindrical part 27. The cylindrical part 27 is thus arranged to prevent the thinner
of the ink from evaporating. The position of the cylindrical part 27 is defined by
stops 26.
[0028] When the ink tray turns clockwise, a doctor blade 24 comes down to scrape off the
ink while another doctor blade 25 stays clear of the plate, in an idle state. In the
event of counterclockwise movement of the ink tray, the blade 25 comes down while
the blade 24 stays idle. Meanwhile, ink guides 15-1 and 15-2 are arranged to move
upward or downward concurrently with the doctor blades 25 and 24, so that the ink
can be kept at uniform thickness over the upper surface of the plate. The ascent and
descent of these doctor blades 24 and 25 and the ink guides 15-1 and 15-2 can be accomplished
by some suitable means such as an air cylinder or the like.
[0029] In accordance with this invention, the plate or the doctor blade is arranged to be
moved either in a stepwise rotating manner or in a back-and-forth rotating manner.
By virtue of this arrangement, thinners evaporation can be prevented, to permit a
high speed printing over a relatively wide area without any special cylindrical doctor
blade as compared to the prior art arrangements where the prevention of thinners evaporation
has not been possible.
[0030] While the printing process has been described with reference to Figure 4(a), a printing
operation in accordance with the invention can also be carried out in the following
manner. Different designs may be etched into the design parts of the plate. Meanwhile,
a plurality of vertically movable pads may be mounted on a stepwisely rotatable index
device. By such an arrangement, a number of different designs, equal to the number
of steps, can be printed one after another. Further, the use of a computer control
arrangement for both the index drives arranged for the plate and the pad permits selection
of any desired design. Such an arrangement is advantageous for a printing line for
printing many different kinds of printed matter running at random, as well as for
printing various kinds of printed matter running in small quantities, because no resetting
work is required by each change of the printed matter.
[0031] Figure 8 is a supplementary illustration of the printing process which may be carried
out by the arrangement according to this invention, showing the three steps of doctoring,
descent and ascent of the printing pad, and ink refresh. In the second step, the ink
remaining in the recessed parts of the printing plate after the ink reception by the
pad hardens to some degree because of the vaporization of the thinners and the thus
hardened ink will not be restored to its initial soft state immediately when fresh
ink is applied by the doctoring. Therefore in the third step no relative movement
between the printing plate and the doctor blade occurs so as to allow sufficient time
for the hardened ink to be restored to its initial fresh state by virtue of the solvent
action of the thinners in the fresh ink.
1. An inking and doctoring process for a pad printing machine in which ink is applied
to a design provided on a substantially flat printing plate (18), the plate is then
doctored by means of a doctor blade (16; 24, 25) and then ink is picked up from the
recessed parts of the printing plate (18) by means of a pad provided as a part of
the printing machine while the doctor blade (16; 24, 25) is at least substantially
in a state of rest, which process is characterised by the performance of a doctoring
step in which the printing plate (18) and the doctor blade (16; 24, 25) are rotated
relatively to effect the doctoring of the plate (18) before the printing machine pad
picks up ink from the printing plate (18).
2. An inking and doctoring process according to claim 1, further characterised in
that the relative rotation between the printing plate (18) and the doctor blade (16)
is performed stepwise with the relative rotation each time being in the same sense,
preferably with the doctor blade (16) being maintained spatially fixed and the printing
plate (18) being rotated stepwise with respect to the doctor blade (16).
3. An inking and doctoring process according to claim 1, further characterised in
that the relative rotation between the printing plate (18) and the doctor blade (24,
25) is performed in a back-and-forth manner, preferably with the printing plate (18)
being maintained stationary and the doctor blade (24, 25) being rotated relative to
the printing plate (18).
4. An inking and doctoring process according to any of the preceding claims, further
characterised in that each cyclic operation includes a step during which no relative
movement between the printing plate (18) and the doctor blade (16; 24, 25) takes place,
during which step the ink on the printing plate (18) is refreshed.
5. An inking and doctoring process according to any of claims 1 to 4 further characterised
in that ink in an ink tray (13) in which the printing plate (18) is located covers
the printing plate other than where doctoring has taken place.
6. An inking and doctoring arrangement for a pad printing machine including an ink
tray (13) in which is mounted a substantially flat printing plate (18), a doctor blade
(16; 24, 25) arranged to scrape ink off the upper surface of the printing plate (18)
and an ink tray cover (12) which is disposed over the ink tray (13) to minimise evaporation
of ink components, characterised in that there is provided a drive device (11) adapted
to cause relative rotational movement between the printing plate (18) in the horizontal
plane and the doctor blade (16; 24, 25) to effect doctoring of the plate.
7. An inking and doctoring arrangement according to claim 6, further characterised
in that the doctor blade (16) is mounted on a fixed part (12) and the drive device
(11) is arranged to cause the ink tray (13) and printing plate (18) therein to rotate
preferably in a stepwise manner each time in the same sense thereby perform doctoring
of the printing plate (18).
8. An inking and doctoring arrangement according to claim 6 or claim 7, characterised
in that the doctor blade (16) is shaped to define a closed area within which a design
on the printing plate (18) to be printed is caused to lie when the inked design is
to be transferred to the printing machine pad.
9. An inking and doctoring arrangement according to claim 6, further characterised
in that the ink tray (13) and printing plate (18) are mounted on a fixed part and
the drive device is adapted to cause the doctor blade (24, 25) to move relative to
the printing plate, preferably in a back-and-forth rotational manner.
10. An inking and printing arranged according to claim 6 or claim 9, characterised
in that two doctor blades (24, 25) are provided, arranged alternately to contact the
printing plate (18) depending upon the sense of relative movement between the doctor
blades and the printing plate.
1. Ein Farbauftrags- und Rakelverfahren für eine Farbkissendruckmaschine, bei dem
Farbe auf ein Muster aufgetragen wird, das sich auf einer im wesentlichen flachen
Druckplatte (18) befindet, die Platte wird dann mit Hilfe einer Rakel (16; 24, 25)
gerakelt und Farbe anschließend von den eingelassenen Teilen der Druckplatte (18)
mit Hilfe eines Kissens aufgenommen, das als Teil der Druckmaschine vorgesehen ist,
während sich die Rakel (16; 24, 25) zumindest im wesentlichen in einem Ruhezustand
befindet, gekennzeichnet durch die Ausführung eines Rakelschritts, bei dem die Druckplatte
(18) und die Rakel (16; 24, 25) relativ gedreht werden, um das Rakel der Platte (18)
zu bewirken, bevor das Druckmaschinenkissen Farbe von der Druckplatte (18) aufnimmt.
2. Ein Farbauftrags- und Rakelvertahren nach Anspruch 1, weiterhin dadurch gekennzeichnet,
daß die relative Drehung zwischen der Druckplatte (18) und der Rakel (16) schrittweise
durchgeführt wird, wobei die relative Drehung jedesmal in der gleichen Richtung erfolgt,
und die Rakel (16) vorzugsweise räumlich befestigt bleibt und die Druckplatte (18)
schrittweise in bezug auf die Rakel (16) gedreht wird.
3. Ein Farbauftrags- und Rakelverfahren nach Anspruch 1, weiterhin dadurch gekennzeichnet,
daß die relative Drehung zwischen der Druckplatte (18) und der Rakel (24, 25) eine
Hin- und Herbewegung ist, wobei die Druckplatte (18) vorzugsweise unbeweglich bleibt
und die Rakel (24, 25) relativ zu der Druckplatte (18) gedreht wird.
4. Ein Farbauftrags- und Rakelverfahren nach einem der vorhergehenden Ansprüche, weiterhin
dadurch gekennzeichnet, daß jeder zyklische Arbeitsvorgang einen Schritt enthält,
bei dem keine Relativbewegung zwischen der Druckplatte (18) und der Rakel (16; 24,
25) stattfindet, und bei dem die Farbe auf der Druckplatte (18) erneuert wird.
5. Ein Farbauftrags- und Rakelverfahren nach einem der Ansprüche 1 bis 4, weiterhin
dadurch gekennzeichnet, daß Farbe in einer Farbschale (13), in der sich die Druckplatte
(18) befindet, die Druckplatte an den Stellen bedeckt, an denen ein Rakeln nicht stattgefunden
hat.
5. Eine Farbauftrags- und Rakelanordnung für eine Farbkissendruckmaschine, die eine
Farbschale (13), in der eine im wesentlichen flache Druckplatte (18) angebracht ist,
eine Rakel (16; 24, 25), die so angeordnet ist, daß die Farbe von der Oberfläche der
Druckplatte (18) abstreift, und eine Farbschalenabdeckung (12), die über der Farbschale
(13) angeordnet ist, um die Verdampfung der Farbbestandteile auf ein Minimum zu beschränken,
umfaßt, dadurch gekennzeichnet, daß eine Antriebseinrichtung (11) vorgesehen ist,
die so angepaßt ist, daß sie eine relative Drehbewegung zwischen der Druckplatte (18)
in der horizontalen Ebene und der Rakel (16; 24, 25) erzeugt, um das Rakeln der Platte
zu bewirken.
7. Eine Farbauftrags- und Rakelanordnung nach Anspruch 6, weiterhin dadurch gekennzeichnet,
daß die Rakel (16) auf einem feststehenden Teil (12) befestigt ist und die Antriebseinrichtung
(11) so angebracht ist, daß sie eine Drehung der Farbschale (13) und der darin befindlichen
Druckplatte (18) bewirkt, vorzugsweise jedesmal schrittweise und in der gleichen Richtung,
um damit das Rakeln der Druckplatte (18) durchzuführen.
8. Eine Farbauftrags- und Rakelanordnung nach Anspruch 6 oder Anspruch 7, dadurch
gekennzeichnet, daß sie einen geschlossenen Bereich definiert, in dem ein zu druckendes
Muster auf der Druckplatte (18) zu liegen veranlaßt wird, wenn das mit Farbe versehene
Muster auf das Druckmaschinenkissen übertragen werden soll.
9. Eine Farbauftrags- und Rakelanordnung nach Anspruch 6, weiterhin dadurch gekennzeichnet,
daß die Farbschale (13) und die Druckplatte (18) auf einem feststehenden Teil befestigt
sind, und die Antriebseinrichtung so angepaßt ist, daß sie eine Bewegung der Rakel
(24, 25), vorzugsweise eine drehende Hin- und Herbewegung, relativ zu der Druckplatte
verursacht.
10. Eine Farbauftrags- und Rakelanordnung nach Anspruch 6 oder Anspruch 9, dadurch
gekennzeichnet, daß zwei Rakeln (24, 25) vorgesehen sind, die so angeordnet sind,
daß sie abwechselnd die Druckplatte (18) berühren, je nach der Richtung der relativen
Bewegung zwischen den Rakeln und der Druckplatte.
1. Un procédé d'encrage et de raclage pour une imprimeuse à tampon dans laquelle l'encre
est appliquée selon un modèle présenté sur une plaque d'impression (18) réellement
plate, la plaque est ensuite raclée au moyen d'une racle (16, 24, 25) et puis l'encre
est enlevée des parties creuses de la plaque d'impression (18) à l'aide d'un tampon
faisant partie intégrante de l'imprimeuse alors que la racle (16, 24, 25) est réelement
à l'état de repos; ce procédé se caractérise par l'exécution d'un raclage durant lequel
la plaque d'impression (18) et la racle (16, 24, 25) sont mises en rotation l'une
relativement à l'autre pour effecteur le raclage de la plaque (18) avant que le tampon
de l'imprimeuse enlève l'encre de la plaque d'impression (18).
2. Un procédé d'encrage et de raclage selon la revendication 1, caractérisé en outre
par le fait que la rotation relative de la plaque d'impression (18) et de la racle
(16) s'effectue graduellement et que cette rotation relative a lieu à chaque fois
dans le même sens, de préférence avec la racle (16) étant maintenue fixe dans l'espace
et la plaque d'impression (18) étant tournée graduellement par rapport à la racle
(16).
3. Un procédé d'encrage et de raclage selon la revendication 1, caractérisé en outre
par le fait que la rotation relative de la plaque d'impression (18) et de la racle
(24, 25) est effectuée avec un mouvement avant-arrière, de préférence avec la plaque
d'impression (18) étant maintenue stationnaire et la racle (24, 25) étant tournée
par rapport à la plaque d'impression (18).
4. Un procédé d'encrage selon l'une quelconque des revendications précédentes, caractérisé
en outre par le fait que chaque opération cyclique comprend une étape durant laquelle
ne se produit aucun mouvement relatif entre la plaque d'impression (18) et la racle
(16, 24, 25); durant cette étape l'encre de la plaque d'impression (18) est rafraîchie.
5. Un procédé d'encrage et de raclage selon l'une quelconque des revendications 1
à 4, caractérisé en outre par le fait que l'encre placée dans un bac à encre (13)
dans lequel se trouve la plaque d'impression (18) couvre la plaque d'impression aux
endroits où le raclage n'a pas eu lieu.
6. Un dispositif d'encrage et de raclage pour une imprimeuse à tampon comprenant un
bac à encre (13) dans lequel est montée une plaque d'impression réellement plate (18),
une racle (16, 24, 25), disposée de manière à racler l'encre à la surface de la plaque
d'impression (18) et un couvercle de bac à encre (12) placé au-dessus du bac à encre
(13) sert à réduire au minimum l'évaporation des composants de l'encre, caractérisé
par le fait qu'il est prévu un appareil d'entraînement (11) apte à provoquer un mouvement
de rotation relatif entre la plaque d'impression (18) sur le plan horizontal et la
racle (16, 24, 25) pour exécuter le raclage de la plaque.
7. Un dispositif d'encrage et de raclage selon la revendication 6, caractérisé en
outre par le fait que la racle (16) est montée sur une pièce fixe (12) et que l'appareil
d'entraînement (11) est disposée de manière à provoquer la rotation du bac à encre
(13) et de la plaque d'impression (18) qui s'y trouve de préférence de manière progressive,
à chaque fois dans le même sens, pour ainsi effectuer le raclage de la plaque d'impression
(18).
8. Un dispositif d'encrage et de raclage selon la revendication 6 ou la revendication
7, caractérisé par le fait que la racle (16) est façonnée pour définir une zone fermée
dans laquelle un modèle sur la plaque d'impression (18) à imprimer vient se placer
quand le modèle encré doit être transféré sur le tampon de la machine d'impression.
9. Un dispositif d'encrage et de raclage selon la revendication 6, caractérisé en
outre par le fait que le bac à encre (13) et la plaque d'impression (18) sont montés
sur une pièce fixe et que l'appareil d'entraînement est apte à provoquer le déplacement
de la racle (24, 25) relativement à la plaque d'impression, de préférence d'une manière
rotative avant-arrière.
10. Un dispositif d'encrage et de raclage selon la revendication 6 ou la revendication
9, caractérisé par le fait que deux racles (24, 25) sont prévues, disposées en alternance
pour être en contact avec la plaque d'impression (18) selon le sens du mouvement relatif
entre les racles et la plaque d'impression.