Note: Descriptions are shown in the official language in which they were submitted.
~ACKGROUND OF THE INVENTION
The present invention relates to a new and improved
method of, and apparatus for, reducing the wear of the doctor
blade, also referred to simply as a doctor, and equally, the
wear of the surface of a gravure printing-image carrier, es-
pecially the printing cylinder, during gravure or intaglio
printing.
With gravure or intaglio printing processes the
surface of the printing-image carrier is freed of excess
printing ink by means of a doctor blade or doctor. For this
purpose, such doctor bears with a certain pressure against
the surface of the printing~image carrier. As is known,
this in turn causes wear of the doctor and wear of the
surface of the printing-image carrier.
Many different attempts have been made to overcome
this drawback. However, up to the present these drawbacks
were predominantly directed to improving the doctor and its
mounting. The solutlons which have been strived for and
found in this respect are either complicated from the stand-
point of fabrication or construction aspects, ox, during
operation do not afford the ~esired success.
.
4 ~ I
Furthermore, there has already been proposed to add
to the printing ink additives intended to reduce the doctor
wear and the damage to the surface of the gravure printing-
image carrier. These attempts however were unsuccessful be-
cause, through che addition o such additives ther~ automati-
cally was negatively affected the chemical and physical pro-
perties of the printing ink. Among other things, this mani-
fested itself by the poor drying properties of the ink. This
in turn resulted in a poor quality of the printed products,
SUMMARY OF THE INVENTION
Hence, with the foregoing in mind, lt is a primary
object of the present invention to provide a new and improved
method of, and apparatus for, reducing the doctor wear and
the wear of the surface of a printing-image carrier for in-
taglio or gravure printing p~ocesses, in a manner not asso-
ciated with the aforementioned limitations and drawbacks of
¦ the prior art proposals.
¦ Another and more specific object of the invention
¦ aims at the provision of a novel method and apparatus which,
¦ without being afflicted by the previously mentioned drawbacks,
¦ enables effectively reducing the doctor wear and the wear of
the surface of the printing-image car~ier,
Yet a further significant object of the present in-
vention is to influence the friction prevailing between the
doctor and printing-image carrier, without impairing the
printing process in a manner such that there can be exten-
sively avoided the disadvantageous effects of such friction.
Now in order to implement these and still ~urther
objects of the invention, which will become more readily
apparent as the description proceeds, the method aspects
of the present invention contemplate applying, independentl~
of the application of the printing ink, a lubricant to the
surface of the printing-image carrier.
As to the apparatus aspects,particularly suitable
for the performance of the method of the invention, such are
characterized by a device for applying the lubricant to the
surface of the printing-image carrier, especially the printing
cylinder used in gravure or intaglio printing.
In contrast to heretofore proposed solutions, with
the teachings of the invention there is not improved the con-
struction of the doctor blade or doctor or its mounting or
support arrangement, rather through the application of a
lubricant there is reduced the friction between the doctor
nd the prlnting-lmage carrier. This affords a corresponding
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11
reduction in ~he wear of the doc~or and the printing-image
carrier. The printing proces~ i9 not disad~anta~eously ~eoted,
so that there i5 no impalrment in the quality o~ the printed
products.
The lubricant or lubricating agent can either be
rubbed or rolled onto the surface of the printing-image car~ier.
The most different devices can be suitably employed for the
application of the lubricant to the surface of the printing-
image carrier, and such various types of applicators will be
disclosed more fully during the course of this description.
It is also possible to use a doctor which contains the lub-
ricant or conducts the lubricant to the surface of the
prlnting-image carrier.
Particularly suitable as the lubricant ls molybdenum
disulfide in powder or solid form or embedded in an appropriate
carrier, for instance plastic material.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood and objects
other than those set forth above, will become apparent when
consideration i9 given to the following detailed description
thereof. Such description makes reference to the annexed
drawings wherein:
113S114
Figure 1 is a perspective, schematic fragmentary
view showing part of a pr~ nting-image carrier and a doctor
blade or doctor;
Figures 2 to 5 respectively schematically show
different devices for applying the lubricant to the surface
of a printing cylinder used during gravure or intaglio
printing; and
Figure 6 is a schematic and simplified illustration
of a gravure printing machine or printing press.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Describing now the drawings, Figure 1, serving
for explaining the problems of wear or the like occurring
during gravure or intaglio printing, shows part of a printing-
im~ge carrier 1 which may be constituted by a plate! a rotating
c~linder or a plate which is clamped or otherwise affixed
to a rotating cylinder. This printing-image carrier 1 possesses,
in known manner, wells 3 or the like enclosed by the screen
webs 2, these wells 3 serving for a reception of printing ink.
To remove the excess printing ink from the surface of the
printing-image carrier and formed by the screen webs 2, there
is provided a doctor blade or doctor 4 which bears by means of
1135114
its contact surface 5 (ohampfer or bevel), with a cert~in
pressure, at the screen webs 2 or equivalent struct~e. As
is known and also previously already mentioned, the~e exists
the problem of the wear or abrasion of the doctor 4 and ~he
wear of the surface of the printing-image carrier 1. As
will be explained more fully hereinafter, this problem is
solved by appl1cation of a lubricant or lubricating agent
between the doctor 4 and the printing-image carrier 1. Ba-
sically there can be used all suitable lubricants, especially
solid, pasty, liquid and pulverulent lubricants. During the
selection of the lubricant it is important that the employed
lubricating agent neither negatively influence the printing
process or the printing quality or the drying properties qf
the printing ink. The lubricant should not cause any im-
pairment in the quality of the printed product. ~he manner
of applying the lubricant between the doctor and the printing-
image carrier is dependent upon the employed lubricant. Based
upon the figures of the drawings there will now be explained
a number of possibilities for the appllcation of the lubricant.
More specifically, in Figures 2 to 5 there are shown
different applicator devices or means for the application of
a lubricant to the surface of a printing cylinder used in
gravure printing. In these figures reference character 6
designates the schematically illustrated printing cylinder
4l
and lts ~urface has been designated by reference character 7.
This cylinder surface 7, as already explalned previously in
conjunct$on with Figure 1, is formed by the screen webs 2 or
equivalent structure. The direction of rotation of the prlnting
cylinder 6 has been indicated by the arrow A.
Now in Figure 2 the applicator device for the appli-
cation of the lubricant to the surface 7 of the printing
cylinder 6 comprises a blade-shaped lubricating or lubricant
body 8 which is pressed at a constant pressure against the
printing cylinder 6, by any suitable means, such as con-
ventional springs or other resilient elements not particularly
shown. The lubricant or lubricating body 8, bears by means
of its contact surface 9, against the cyiinder surface 7.
In order to maintain essentially constant the ~ize of this
contact surSace 9, in the presence of progressive wear, both
of the boudary surfaces 8a and 8b, in other words the upper
and lower surfaces of the lubricant body 8,extend essentially
parallel to one another. With the contact surface 9 remaining
constant and with essentially constant contact pressure the
application of the lubricant to the surface 7 also is essen-
tially constant. The lubrlcant body 8 can comprise a suitable
solld lubricant, or it can also consist of a carrier, formed
for instance of plastic or slntered material, within which
there is embedded the solid lubricant or lubricating agent.
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Due to the movement of the surface 7 of the ~lnting çylind~r 6
past the lubricant body 8 the lub~ican~ is rubbed onto ~he
surface 7, so that a lubricant film is fo~med upon such
surface. The lubricant body 8 is clamped between two holder
plates 10 and 11 or equivalent ~tructure which fixedly retain
the lubricant body 8. In order to prevent irregular wear of
the contact surface 9 of the lubricant body 8 the lub~icant
8 and the holder plates 10 and 11 can be moved, approximately
perpendicular to the direction of rotation A of the printing
cylinder 6, back-and-forth, in the direction of the double-
headed arrow B by any suitable drive which has merely been
schematically indicated by reference character 50. Particularly
suitable as a solid lubricant is molybdenum disulfide.
The lubricant body 8 can also consist of a porous
material to which there is infed in suitable manner a liquid
lubricant. Owing to the capillary action the lubricant or
lubricating agent distributes within the porous lubricant
body 8 and ls applied to the surface 7 of the printing cylinder
6 which moves past such lubricant body 8. As explained in
conjunction with Figure 2, also in this case the lubricant
body 8 can be moved to-and-fro and structured such that the
contact surface 9, with progressive wear, remains essentially
con~tant.
1135~14
As shown in Figure 3, liquid or pasty lubricants
can be applied to the surface 7 of the printing-image carrier
6, by means of an applicator device which can be constructed
similarly to an inking mechanism or device employed for ink
application. The applicator device comprises a supply con-
tainer 12 within which there is located the lubricant or
lubricating agent 13. A substantially lip-shaped applicator
element 14 is connected with the supply container 12. The
appllcator element 14 extends by means of its edge lS at a
slight spacing and approximately parallel to the surface 7
of the printing cylinder 6. The lubricant is applied, by
means of the applicator element 14, to the cylinder surface
7 and distributed over the width of the printing cylinder 6
such that a lubricant film 16 is formed upon the cylinder
surface 7. Depending upon the viscosity and sur~ace tension
of the lubricant the edge 15 of the applicator element 14,
as shown, can extend at a spacing with respect to the surface
7, or, however, can be in contact with such cylinder surface
7. In the last-mentioned case, at least this edge 15, if
not the entire applicator element 14, can be formed of a
wear resistant material, for instance a wear resistant
plastic, and further, She inherent stress or bias of such
edge lS or the applicator element 14 can be beneficially
employed for maintaining edge 15 in contact with the cylinder
surface 7. The use of steel, especially doctor blade steel,
1135~14
is however also possible. In order to avoid any irregular
wear of the edge 15 such edge0 or in fact the entire applicat~r
element 14, can be moved back-and-forth in a directlon trans-
verse to the directlon of rotation A of the printing cylinder-
6, and there again can be us@d for this purpose the drive 50
shown $n Figure 2. A constant flow of lubri~ant can either
be brought about by the capillary action, by a constant lub-
ricant level in the supply container 12, or bY application of
an excess pressure effective upon the surface of the lubricant.
In the last-mentioned case there must be used as the supply
container 12 a closed sup~ly Qontainer or vat 12 equipped with
a cover or closure member 12a, as such has been shown in
broken lines in Figure 3. Opening into this closed supply
container 12 is an infeed liné or conduit 17 ~ar a suitable
pressurized fluid medium, for instance a gas which is at
essentially constant pressure.
With the exemplary embodiment shown in Figures 4
and 5, the lubricant is applied to the surface 7 of the
printing cylinder 6 by means of a rotatably mounted appli-
cator roll 18. This ap~licator roll 18 is in contact with
the printing cylinder 6 and rotates in the direction of th~
arrow C opposite to the direction of rotation A of the
printing cylinder 6. With the exemplary embodiment shown
in Figure 4 the applicator roll 18, during its r~tation,
immerses partially into the lubricant or lubri~cating aqent
13 which i~ located in the 6upply conta1ner or vat 12.
Excess lubricant is removed by the doctor or doct~r blade
19 from the applicator roll 18 and returned back into the
supply container 12. Due to the contact of the applicator
roll 18, carrying the lub~icant, with the cylinder surfa~e
7 there is formed upon the latter a lubricant film 16.
In Figure 5 the applicator roll 18 contacts a~
immersion or immersible roll 20 rotating in the directional
sense D which i5 opposite to the direction of rotation C
of the applicator roll 18. This immersion roll 2~, during
its rotation, immerses partially into the bath of lubricant
13 in the supply container 12, thereby entrains a certain
arnount of lubricant and transfers such to the applicator
roll 18 at the zone of contact therewith. The lubricant
is then applied by the applicator roll 18, similar to the
arrangement of Figure 4, in the form of a lubricant or
lubrication film 16 to the cylinder surface 7 of the printing
cylinder 6. If necessary, there is prqvided a doctor or
doctor blade 19 for the removal of excess lubricant from the
immersion roll 20.
Of course, the lubricant can also be applied to the
surface 7 of the printing cylinder 6 in a different suitable
and therefore not particularly illustrated manner. Liquid
i~
lubricant can be, for instance, sprayed onto the cylinder
surface 7 by means of a suitable sprayiNg device. In the
case of pulverulent lubricant there can be used atomizer
devices which dust or atomize the lubricant unto the cylin
der surface 7. As a further variant there is proposed the
utilization of a vaporizing device, by means of which the
lubricant can be vapor deposited onto the cylinder surface
7. This possibility particularly comes under consideration
when working with liquid lubricants.
The site of application of the lubxicant at the
surface 7 of the printing cylinder 6 basically can be
differently selected, and especially ~s dependent upon
the nature of the employed lubricant, the nature of the
employed application process and the construction of the
printing machine. Based upon the showing of Figure 6,
illustrating purely schematically and in markedly simplified
form a gravure or intaglio printing machine or press, there
will now be explained the different possible ways of applying
the lubricant. The gravure printing machine comprises a
printing cylinder 6, whose surface 7 is freed of printing
ink by means of a doctor blade or doctor 4. This doctor 4
is supported in known manner in a doctor holder or mounting
arrangement 21. The printing cylinder 6, rotating in the
direction of the arrow A, during its rotation partially
immerses into the lnking vat 23 of an inking device 24 and
113511~
whicll contains the printing ink. The web-shaped material 25,
which is to be printed, is moved between the printing cylinder
6 and an impression or pressure cylinder 24. Along the printing
line 26 there occurs transfer of the printing ink from the
printing cylinder 6 to the web material 25. As to what has
been described above and illustrated such corresponds to a
conventional gravure printing machine. According to the
invention, there is applied a lubricant to the surface 7 of
the printing cylinder 6 in one of the previously described
manners. ~he application of the lubricant can be accomplished,
for instance between the inking device 22 and the doctor 4
(Sector I), between the doctor 4 and the printing line or nip 26
(Sector II), or between the printing line 26 and the inking
device 22 ~Sector III). However, it is also possible to
apply the lubricant by means of the doctor 4. For this pur-
pose it is for instance conceivable to embed the lubricant
in the doctor or doctor blade 4 so that it appears and is
available at the base or free end of the doctor 4. It is
also possible to conduct the lubricant through the doctor
4 to ~e contact zone between such doctor 4 and the printing-
image carrier or pxinting cylinder 6. In particular, liquid
lubricant could be applied to the surface of the doctor 4,
from which location the lubricant is infed, by meanq of such
doctor 4, to such contact zone between the doctor 4 and the
printing cylinder 6. This infeed of the lubricant, with the
aid of the doctor or doctor blade 4, has been symbolized in
Figure 6 by the position IV.
~i351~4
While there are shown and descxibed present preferred
embodiments of theinvention, it is to be distinctly understood
that the invention is not limited thereto, but may be other-
wise variously embodied and practiced within the scope of the
wl- 1~ CO~DI~C~Y,
