Inker with controlled zone ink distribution, and method of controlling ink transfer between cylinders of a printing machine

To control the amount of ink transferred between an ink application cylinder (2) and an ink supplying cylinder (1) having a cellular surface, such as an anilox roller or another roller or cylinder having ink receptor cells and/or a further cylinder (3) such as a plate cylinder, the ink application cylinder (2) is formed with a yieldingly compressible surface and the yieldingly compressible surface is pre-compressed by application of a surface compression roller (4) thereagainst. The surface compression roller (4) deforms the yieldingly compressible surface (14) which does not expand instantaneously; it may be located in advance of engagement with the ink supplying cylinder (1) or with the plate cylinder (3) by a distance shorter than the decay distance of the compression effected by the surface compression roller. A plurality of such pre-surface compression rollers may be provided, located axially adjacent each other, to control the amount of ink being transfered to the plate cylinder in axially adjacent zones.

Reference to related patents and applications assigned to the assignee of 
the present application: U.S. Ser. No. 07/607,533, filed Nov. 1, 1990, 
JOHN; U.S. Ser. No. 07/604,772, filed Oct. 26, 1990, JOHN; U.S. Ser. No. 
07/593,040, filed Oct. 5, 1990, JOHN. 
U.S. Pat. No. 4,805,530, KOBLER et al (to which German 37 06 011 
corresponds); U.S. Pat. No. 4,938,133, Bock et al, 
Reference to related literature: 
Gluck: "Untersuchung des Rollverhaltens von Mehrwalzen-Systemen unter 
Einbeziehung einer viskoelastischen Walze" ("Investigation of Behavior of 
Rollers including a Viscous Elastic Roller in Multi-Roller Systems"), TH 
Darmstadt (Technical University Darmstadt), 1976; page 166 et seq. 
FIELD OF THE INVENTION 
The present invention relates to an inker and to a method of inking 
cylinders of a printing machine, and more particularly to an inker having 
a cylinder with a cellular surface, such as an anilox cylinder or roller 
and, further, an ink transfer roller or cylinder which has a soft or 
resiliently yielding, compressible surface, to transfer ink from the 
cylinder with the cellular surface to a further cylinder, for example a 
plate cylinder or the like. 
DEFINITION 
The term "cellular surface" will be used hereinafter to describe an ink 
transfer surface having small ink receptor depressions or cells, which are 
used, for example, in anilox rollers or cylinders, gravure cylinders or 
the like. 
BACKGROUND 
An inker with an anilox roller with a compressible surface transferring ink 
to a transfer cylinder, is described for example, in the referenced U.S. 
Pat. No. 4,805,530, to which German Patent 37 06 011 corresponds. In 
accordance with this reference, the cellular surface roller has a 
compressible layer; by controlling the compression, the quantity of ink 
transferred to a plate cylinder can be controlled. The layer is compressed 
by a doctor blade or similar stripper element. Compressing the 
compressible layer by a doctor blade causes substantial wear and tear on 
the cellular roller or cylinder. 
THE INVENTION 
It is an object to provide an inker in which the quantity to be transferred 
by the inker can be controlled, and to a method of controlling this 
quantity, in which the respective rollers or cylinders of the inker have 
substantially less wear than in prior art structures. 
Briefly, an ink transfer cylinder is provided which has a yieldingly 
compressible surface. The ink transfer cylinder is in ink transfer 
relation with an ink supplying cylinder which has a cellular surface. The 
ink transfer cylinder is in engagement with a further cylinder, for 
example a forme or plate cylinder, to transfer ink thereto. In accordance 
with a feature of the invention, a surface compression roller is in 
engagement with the yielding compressible surface of ink transfer 
cylinder. The extent of compression applied by the surface compression 
roller is controllable to thereby control the amount of ink being 
transferred between the ink transfer cylinder and the further cylinder. 
The compression control provides for precompression of the yielding 
compressible layer in advance of contact of the ink transfer cylinder with 
the further, for example forme cylinder. This pre-compression permits the 
yieldingly compressible surface to expand for a limited controlled amount 
before engagement with the further cylinder. 
In accordance with a feature of the invention, the surface compression 
roller can be placed in advance--with respect to the direction of rotation 
of the ink transfer cylinder--of engagement with the ink supplying 
cylinder having the cellular surface, or in advance of engagement with the 
further cylinder, for example the plate cylinder.

DETAILED DESCRIPTION. 
The invention is directed to supplying ink to a printing machine cylinder, 
for example a plate or forme cylinder 3. FIG. 1 shows the inker having an 
ink supplying cylinder 1 with a cellular surface; for short, cylinder 1 
will be referred to hereinafter as a "cellular" cylinder. Its surface is 
formed with small depressions or cells, which may, for example, be a hard 
surface. An ink transfer cylinder 2 is in surface contact with the 
cellular cylinder 1. The ink transfer cylinder 2 has a resilient, 
yieldingly compressible surface. Ink removed by the cellular surface 1 
from an ink trough 11 is transferred first on the ink transfer cylinder 2, 
and from the ink transfer cylinder 2 on the plate cylinder 3. The cellular 
cylinder 1 has ink stripped off therefrom by a doctor blade 12. The ink 
transfer cylinder can be an ink application cylinder. 
In accordance with the present invention, an auxiliary roller or cylinder, 
forming a surface compression roller 4, is in controlled pressure 
engagement with the ink application cylinder 2. 
The quantity of ink being transferred from one roller or cylinder to 
another roller or cylinder depends on the width of the engagement zones of 
the respectively engaged cylinders or rollers. The engagement zone is also 
referred to as an ink transfer or pressure zone. Reliable transfer of 
printing ink from one roller onto another is possible only when the 
respective rollers are in pressure contact engagement. The pressure is 
also applied on the ink within the engagement or ink transfer zone. The 
ink, thus, transfers from one roller to the other. Engagement, under 
pressure, results in elastic deformation of the surface of one of the 
rollers at the engagement or pressure zone. 
The phenomenon of ink transfer has been studied, see Gluck: "Untersuchung 
des Rollverhaltens von Mehrwalzen-Systemen unter Einbeziehung einer 
viskoelastischen Walze" ("Investigation of Behavior of Rollers including a 
Viscous Elastic Roller in Multi-Roller Systems"), TH Darmstadt (Technical 
University Darmstadt), 1976; page 166 et seq. 
The above-referenced literature teaches that elastic jackets or sleeves 
which are compressed in a pressure zone require a predetermined period of 
time until the deformation is no longer effective. This time, forming what 
may be termed an elastic memory, can be referred to as the retardation 
time. Placing two pressure zones closely spaced from each other has the 
result that the remaining deformation resulting from the first pressure 
zone will have an effect on the deformation in the next pressure zone. 
The present invention makes use of this phenomenon. If the deformation in 
the next pressure zone is smaller, less ink will be transferred thereby. 
Under ordinary operating conditions, a first deformation followed by a 
second deformation is highly undesirable. To prevent a first deformation, 
for example due to engagement of a roller on an elastic surface of another 
roller, from having this effect, it is necessary to space the 
circumferential distance of the rollers sufficiently wide so that the 
compressible layer can expand to its nominal diameter. 
In accordance with the present invention, this effect of a smaller 
deformation of a compressible layer subsequent to the first compression is 
used and is specifically caused, since it can be utilized to control the 
quantity of ink being transferred. 
Referring again to FIG. 1: 
The inker includes a system 5 which permits application of the surface 
compression roller 4 on the ink application cylinder 2 with controlled 
surface pressure. As shown in FIG. 1, the system 5, essentially, includes 
a lever 7 pivotable about a pivot 6. The surface compression roller 4 is 
located at the far end 10 of the lever 7. A fluid controlled 
piston-cylinder unit 8 is coupled intermediate the roller 4 and the pivot 
6 on the link or lever 7. The piston-cylinder unit 8 secured, for example, 
to the side walls of the printing machine is so controlled that the lever 
7, and hence the compression roller 4, is engaged against the ink 
application roller 2 with the yieldingly compressible surface, to cause a 
predetermined deformation of the surface of the roller 2 just in advance 
of its contact with the cellular cylinder 1. 
Control of ink transfer, with reference to FIGS. 2, 3 and 4: 
FIG. 2 is a schematic representation of the deformation of the ink 
application roller 2 by the cellular roller 1, engaged against roller 2 
under pressure, and with the auxiliary or compression roller 4 merely 
idling against the ink application cylinder 2, without surface compression 
thereagainst. The ink application roller 2 is formed of a core 13, for 
example of steel, and an elastic coating or jacket 14. The elastic coating 
or jacket may, for example, be a rubber layer or jacket. As seen, the ink 
application roller 2 is deformed by engagement with the cellular cylinder 
1 at an engagement or ink transfer zone 15. The deformation depends on the 
elasticity characteristics of the material of the jacket 14, with respect 
to depth of compression, and hence the width of the engagement zone 15, as 
well as on the degree of relaxation of the compressible layer, that is, 
the distance and time of decay of the deformation and until the roller 
has, again, reached its nominal diameter. The deformation decays according 
to an e-function, and has decayed after a predetermined time, at the 
latest until the respective incremental area of the zone again meets the 
cellular cylinder 1. For ease of visualization, a broken line has been 
entered in FIG. 2 illustrating the nominal circumference of the cylinder 
2, without deformation. 
FIG. 3 illustrates, schematically, the deformation of the ink application 
roller 2 by the cellular roller 1 with the compression roller 4 in a first 
position, and compressively engaged against the ink application cylinder 
or roller 2. Looked at in the direction of rotation of the ink application 
cylinder 2, the surface is deformed first by the pressure engagement of 
the surface compression roller 4. This deformation of the layer 14 of the 
roller 2 decays within a predetermined time, that is, with reference to 
the ink application roller, within a predetermined circumferential 
distance on the roller. 
The cellular roller 1 is located just downstream of the compression roller 
4, preferably within a comparatively small distance. It, also, causes 
deformation of the circumference of the ink application roller 2. The 
deformation caused by the compression roller 4, however, has not yet 
decayed, so that the second deformation will be only along a small 
engagement or ink transfer zone 16, which is smaller and circumferentially 
shorter than when the compression roller is not in engagement, as shown in 
FIG. 2. Again, for ease of visualization, the circumference of the 
undeformed roller 2 is shown in broken lines. It can readily be seen that 
the width of the engagement zone 15 will depend on the depth of the 
deformation previously caused by the surface compression roller 4. 
In accordance with another feature of the invention, the ink application 
cylinder 2 is engaged against a plate cylinder 3. The compression roller 4 
is located in advance of the engagement of the ink application cylinder 2 
with the plate cylinder 3, as seen in FIG. 4. Looked at in the direction 
of rotation of the ink application roller 2, it is first deformed by the 
compression roller 4, the deformation decaying within a predetermined time 
or, with respect to the roller when it rotates, within a predetermined 
distance at the circumference of the roller. The plate cylinder 3 is 
located behind the compression roller 4, preferably relatively closely 
thereto. It, also, causes deformation of the surface of the application 
roller 2. Since, however, the pre-deformation caused by the roller 4 has 
not yet decayed, the second deformation will not be fully effective so 
that the engagement or ink transfer zone 17 between the ink application 
roller 2 with the compressible yielding surface and the plate cylinder 3 
will be less wide than without the presence or engagement of the 
compression roller 4. Again, and for better understanding, the 
circumference of the ink application roller 2, without deformation, is 
shown in broken line. The width of the engagement zone 17 depends on the 
depth of the pre-compression of the surface caused by the roller 4. 
The exact values, which determine the dependency of the change of the width 
of the zone 16 or 17 of the ink application roller 2 with respect to the 
width of the engagement zone 15 or 17, respectively, will depend on the 
pressure exerted by the pressure roller 4 against the elastic layer 14. 
This relationship depends on the behavior of the visco-elastic layer 14, 
which is yielding, resiliently compressible. A few experiments will 
readily determine suitable engagement pressures for the pressure or 
compression roller 4 so that the width of the respective engagement or ink 
transfer zone 16 or 17 can be determined to provide for the requisite 
transfer of ink, not too much and not too little. 
Use of pre-compression or surface compression rollers 4 located in advance 
of ink transfer from the ink application roller 2, but not extending over 
the entire width of the roller 2, can be used to provide different 
quantities of ink with respect to different axial zones of the ink 
application roller. FIGS. 5 and 6, highly schematically, illustrate a 
preferred embodiment of the arrangement for variable engagement of the 
surface compression roller 4 against the ink application roller 2. 
As best seen in FIG. 5, the region in which ink is transferred between the 
ink application roller and another cylinder or roller is subdivided into a 
plurality of zones, of which, for example, two zones are shown in FIG. 5. 
A plurality of independently adjustable surface compression rollers 4 are 
engaged against the ink application roller 2. The number of zones, and 
hence the number of the pre-compression or surface compression rollers 4 
is freely selectable. Since each of the rollers 4 is similarly supported 
and engaged, only one of the rollers will be described since the same 
description is equally applicable to all. 
As seen in FIG. 6, the pre-compression roller 4 is retained in a generally 
U-shaped carrier 18, parallel to the ink application roller 2. The roller 
carrier 18 has two side legs, within which the pre-compression roller 4 
can rotate. The carrier structure 18 for the pre-compression roller 4 is 
located in the interior space of a generally U-shaped cross rail 22 (FIG. 
6), secured between the walls 20, 21 of the inker. The cross rail extends 
essentially parallel to the axis of rotation of the ink application roller 
2. The roller carrier 18 is secured to the legs of the cross rail 22 by 
bearing box 23, secured to the cross rail for example by screws (not 
shown). The roller carrier 18 can pivot about an axis or shaft 24, 
parallel to the ink application roller 2. The center leg 19 of the 
U-shaped carrier 18 is elongated beyond the width of the side legs, so 
that, together with the side legs, it forms a double-arm lever, pivotable 
about the shaft 24. The lever need not necessarily be a right-angle lever. 
The center leg 19, thus, is extended so that applying pressure against the 
free end of the leg 19 causes application of pressure of the surface 
compression roller 4 against the ink application roller 2. This 
application of pressure, in the example of FIGS. 5 and 6, is obtained by 
engagement with an adjustment screw 25 passing through the connecting 
center portion of the cross rail 22. Upon screwing-IN of the screw 25, the 
roller 4 is engaged against the ink application roller 2 with increasing 
pressure; screwing-OUT of screw 25 lowers the engagement pressure until 
the roller 4 is removed from surface contact with the ink application 
roller 2, due to the weight of the roller 4 tending to hold the lever 19 
in engagement with the screw 25 at all times. 
The screw 25 can be operated, selectively, by hand, or can be automatically 
controlled. If automatic control is desired, the screw 25 is then 
preferably replaced by a spindle driven by an electric motor, for example 
a stepping motor. 
FIGS. 7 and 8, schematically, show another and suitable and desirable 
embodiment to change the engagement pressure of the surface compression 
roller on the ink application roller 2. The surface engagement roller 4 is 
rotatable about a shaft 27 in an eccentric 26. Shaft 27 is parallel to the 
axis of the ink application roller 2. The eccentric 26 is pivotable about 
an eccentric bearing 28, having a rotation axis parallel to the axis of 
rotation of the ink application roller 2. A pneumatic cylinder 29, coupled 
by a rod 30 with the eccentric 26, permits pivoting of the eccenter 26; in 
dependence on the direction of pivoting, the pressure roller 4 is engaged 
more or less against the ink application roller 2. Upon release of 
pressure in the unit 29, the roller 4 will be out of contact with the 
roller 2. 
FIG. 8 illustrates the arrangement, partly in section, which shows 
specifically that the pneumatic cylinder 29 is pivotably secured to a side 
wall 21 of the inker with a pivot bolt 31. The piston cylinder unit 29 can 
be controlled, as well known, by suitable control systems, not shown. 
The inker of the present invention, and particularly inkers with zone 
engagement rollers, has the advantage that the cellular roller can have a 
hard surface, so that it has a long life and is not easily worn. The ink 
application roller, in contrast, is formed with an elastically 
compressible surface, as is customary in inkers of many constructions. The 
plate cylinder, usually, also has a hard surface. The roller sequence, 
thus, hard-yielding-hard surface, customary in inkers of this type, can be 
retained and, yet, the quantity of ink being transferred can be easily 
controlled. 
Various changes and modifications may be made, and any features described 
herein may be used with any of the others, within the scope of the 
inventive concept.