Inking device for printing press and an inking dosing member construction

The inking device of a printing machine is composed of an inking roller, providing an elastic surface, the inking roller producing a pre-dosed ink layer on the inking rollers. A dosing strip wipes off the pre-dosed ink layer and leaves the quantity necessary for the transfer onto a stereo cylinder, the wiped off excess ink running off freely. For self-cleaning purposes, the dosing strip carries out a movement preferably in the direction of the circumference of the inking roller, so that the area forming the dosing slot which is in contact with the inking roller is continuously modified.

BACKGROUND OF THE INVENTION 
1. Field of the Invention The invention relates, in general, to printing 
machines and, in particular, to a new and useful inking device for a 
printing press, comprising at least one stereo cylinder bearing a printing 
block, one inking roller with an elastic surface which can be joined to 
the stereo cylinder, an inking device, which inks up the inking roller and 
a dosing device which can be joined to the inking roller. A similar 
arrangement is known from the German Publication No. 32 25 982. Here the 
ink is transferred from an inkwell onto the inking roller covered by an 
elastic surface, the inkwell being, defined by a wall holding back the ink 
on the one side, and by a dosing member on the other side. The dosing 
member, being joined virtually tangential to the inking roller produces on 
the inking roller a thin ink layer suitable for the transfer onto the 
stereo cylinder. Hence, it holds back the ink in the inkwell except for 
the quantity guided through the slot between dosing member and inking 
roller. Since the quantity of ink carried off is very small, the ink 
supply lasts very long in the inkwell. 
By reason of the relatively large resting or supporting surface of the 
dosing member, a huge hydrodynamic pressure is built up in the ink slot. 
In order to obtain a sufficiently thin and constant ink layer, the dosing 
member has to be pushed with a large a mount of power against the elastic 
surface of the inking roller. This high power (engagement power) causes a 
high strain of the elements taking part in the dosing process, which 
entails a high wear of these elements. It has to be noted that along with 
an increasing strain of these elements, an extreme heating up, especially 
of the ink, is caused. The ink heats up particularly in the region of the 
edge of the dosing member, since the ink supply is carried off from the 
dosing slot very slowly. This rise of temperature can be followed by a 
change of the property of the ink, which affects the printing quality 
immediately. Cooling devices of correspondingly huge dimensions are 
supposed to keep the heating under control. 
As a consequence of the pushing pressure acting on the dosing member, 
necessary for the hydrodynamic pressure of the ink in the dosing slot, 
and, as a consequence of the virtually tangential joining of the dosing 
member to the inking roller, there is an additional danger that the front 
edge of the dosing member can be torn into the inking roller by reason of 
the elastic fashioning of the surface of the inking roller. This is 
especially likely to happen when there is a lack of ink, and can cause 
very severe damage to the entire printing press. 
The turbulence occurring in the inkwells which is intended to keep the edge 
of the dosing member free from dirt substances certainly causes 
disturbances in the ink layers has to provide a high evenness. This 
turbulence, however, does not exclude reliably all pollution of the edge 
of the dosing member. However, the dirt substances clinging to the edge of 
the dosing member have the effect that the ink layer on the inking roller 
shows stripes, which are transferred onto the plate cylinder in spite of 
the ink supply swing rollers and thus can be seen on the printed copy. If 
no measures are taken these dirt substances remain clinging on the edge of 
the dosing member and influence the printing quality negatively, until the 
dosing member is cleaned. 
Other attempts to produce an ink layer on an inking roller having an 
elastic surface by means of a single dosing element, such as with the ink 
layer providing all the necessary conditions for the transfer onto the 
stereo cylinder, have failed substantially because of the pollution 
problems which occur. For this reason, none of the solutions suggested so 
far could be accepted in general. 
SUMMARY OF THE INVENTION 
The present invention provides an inking device with as few rollers as 
possible and which transfers an ink layer, which has been produced 
directly on the elastic surface of the inking roller providing an elastic 
surface, onto a printing block carried on a stereo cylinder. The evenness 
of the ink layer is guaranteed during the printing procedure without 
exposing the inking rollers which provides an elastic surfaces to too much 
strain. This wear and the heating can be kept very low. At the same time 
the dosing element is supposed to eliminate the interfering dirt 
substances at the dosing edge. 
In accordance with the invention, the inking device produces a pre-dosed 
ink layer on the inking roller and the dosing device is composed of at 
least one dosing strip, which wipes off the pre-dosed ink layer on the 
inking roller and leaves the necessary quantity for the transfer onto the 
stereo cylinder. The excess ink wiped off by the dosing strip runs off 
freely. The dosing strip is attached in such a way that at least the part 
forming the dosing slot can be moved or oscillated for self cleaning 
purposes. Preferably, the movement is made in the direction of the 
circumference of the inking roller, so that continuously another region of 
the dosing strip forms the dosing slot with the inking roller. 
The oscillating movement of at least one part of the dosing strip to a 
small extent avoids very efficiently an accumulation of dirt substances 
and keeps them from clinging to the edge of the dosing strip, because the 
region of the dosing strip which is in action is changing all the time. 
Thus the polluting substances are continuously washed away by the excess 
ink wiped off by the dosing strip and by the dosed ink layer itself, so 
that a formation of stripes on the inking roller can be excluded. 
Turbulences, which could affect the dosed ink layer are substantially 
avoided because only an ink layer which is predosed in the inking roller 
comes to the dosing strip and because the excess ink can flow off without 
a problem. This excess ink is collected advantageously by an accumulator 
tank and either is guided to an ink treating installation and then back to 
the inking device, or directly back to the inking device. By the choice of 
suitable dimensions of the pre-dosed ink quantity, carried out by the 
inking device, and by the fact that the ink remains for a very short time 
in the inking device, neither the ink nor the elements taking part in the 
production and dosage of the final ink layer are excessively heated up, so 
that an additional cooling becomes unnecessary. 
This inking device avoids also the so called "ghost images" on the printed 
product. The inking device produces continuously a new ink layer on the 
inking roller reduced to the necessary quantity by the strip and then is 
transferred to the printing block. Thus the inking device can provide 
another, preferably smaller diameter than the stereo cylinder. 
As a further improvement of the invention and the above measures, the 
oscillating movement of the dosing strip in the direction of the 
circumference of the inking roller can be obtained advantageously by 
providing a cylindrical dosing edge for the dosing strip and by fashioning 
the dosing strip swingable around the axis of the cylinder defined by the 
cylindrically rounded edge. The positioning of the dosing strip is carried 
out suitably by providing the trunnions disposed on the front sides of the 
dosing strip, the axis of rotation of which coincides with the axis of the 
cylinder defined by the cylindrically rounded edge. Thus it is guaranteed 
that the thickness of the dosing slot and the shape of the dosing slot 
stay exact when the dosing strip is swung. 
A further advantageous development of the features of the invention can be 
carried out by connecting the dosing strip flexibly with two parallel 
control levers. These two control levers are articulated to two levers 
which are parallel to the dosing strip. The rocking levers are kept in 
their one end in stationary bearings. The turning points of the stationary 
bearings and the turning point of the axis of rotation of the dosing strip 
is disposed on one straight line. Thus no bearings have to be set up in 
the immediate surroundings of the surface of the inking roller. 
Furthermore several dosing strips can be disposed over the width of the 
inking roller. The adjustment of the dosing slot between inking roller and 
dosing strip is carried out in an easy way by the fact that one of the 
stationary bearings of a rocking lever is adjustable around the other 
stationary bearing of the other rocking lever by corresponding means. 
In order to protect the very precisely treated dosing edge of the dosing 
strip, this dosing edge can be covered advantageously with a supple plate 
like a foil, which is attached in such a way, that it can be easily 
exchanged. 
The movement of the area of the dosing strip forming the dosing slot can be 
carried out by moving the foil chucked over the dosing strip in the 
direction of the circumference of the inking roller oscillating to an fro. 
This has the advantage that the dosing strip can be disposed stationary. 
In the case of all these described embodiments it is possible to dispose in 
the known way several dosing strips and inking rollers being several pages 
wide next to each other for printing presses which are several pages wide. 
This arrangement side by side renders possible an ink separation over the 
width of a whole page without a problem. 
Accordingly, it is an object of the invention to provide a dosing strip 
which is engageable with an inking roller and which comprises a 
substantially wedge-shaped member having a surface with a portion which is 
rounded and which may be selectively engaged with an elastic surface of an 
inking roller over a varied arcuate range by moving the dosing strip. 
A further object of the invention is to provide a dosing strip for 
engagement with an inking roller having an elastic surface which comprises 
a wedge-shaped member and means for engaging a stretching strip over the 
member which is positioned to engage over a rounded portion and which may 
be varied by either rotating the strip member or varying the position in 
which the strip material over the wedge-shaped member is engaged with the 
elastic surface of an inking roller. 
A further object of the invention is to provide a printing press 
arrangement which includes an inking roller which has an elastic surface 
which is rotated in an ink supply to pick up a pre-dosed ink layer on the 
inking roller and which comprises a dosing strip which has a curved 
surface engageable with the inking roller and which is mounted by means 
which permit it to be moved so that the curved surface thereof varies its 
position of contact with the inking roller. 
A further object of the invention is to provide an inking device which is 
simple in design, rugged in construction and economical to manufacture. 
The various features of novelty which characterize the invention are 
pointed out with particularity in the claims annexed to and forming a part 
of this disclosure. For a better understanding of the invention, its 
operating advantages and specific objects obtained by its uses, reference 
is made to the accompanying drawings and descriptive matter in which 
preferred embodiments of the invention are illustrated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to the drawings, in particular, the invention embodied therein 
comprises an inking device for a printing press which includes a rubber 
blanket cylinder 1 and stereo cylinder 4 which are in rotating engagement 
and with an inking device which picks up ink and delivers it to an inking 
roller 6 which, in turn, transfers it to a printing block of a stereo 
cylinder 4. 
The printing press which is represented diagrammatically in FIG. 1 is 
composed of one rubber blanket cylinder 1, to which a counter pressure 
cylinder 2 is joined, which can be fashioned as a further rubber blanket 
cylinder. 
The web of paper 3 to be printed is lead between the rubber blanket 
cylinder 1 and the counter pressure cylinder 2 and is printed. A stereo 
cylinder 4, bearing printing blocks is joined to the rubber blanket 
cylinder 1. A diagrammatically represented known damping device 5 is 
attached to this stereo cylinder 4, the damping device transferring the 
damping means onto the printing blocks. An inking roller 6, which provides 
an elastic surface, is in contact with the plate cylinder 4 as well. On 
this inking roller 6 a pre-dosed ink layer 8 is produced by an inking 
device 7 over the whole width of the inking roller, the ink layer showing 
a constant quantity, the thickness of the ink layer 9 which is to be 
transferred onto the stereo cylinder 4. The inking device 7 of the present 
embodiment is composed of one inkwell 10 providing an ink measuring 
instrument 11 which is adjustable in the known way. 
Other devices are conceivable, which are known, and which can produce a 
pre-dosed ink layer onto an inking roller 6. The pre-dosed ink layer 9 
which is taken by the inking roller 6 is wiped off by a dosing strip 12, 
which is inserted after the inking device 7. Thus the ink layer 9, which 
can be transferred onto the stereo cylinder 4 is produced. The excess ink 
13, which has been wiped off by the dosing strip runs off freely into an 
accumulator tank 14, from which the accumulated ink is guided directly 
into the inking device 7 or in an ink treatment installation, which is not 
shown and from there it is pumped back into the inking device 7. 
The ink layer 9, which can be transferred onto the stereo cylinder 4 shows 
an even thickness over the entire width of the inking roller 6. This 
thickness can be adjusted by a stronger or less strong joining of the 
dosing strip against the inking roller 6, which can be effected by known 
adjusting mechanisms, which are represented in FIG. 3, for example. 
The inking device 7 produces continuously a newly pre-dosed ink layer 8 on 
the inking roller 6, so that the inking roller, which rotates with the 
same circumference speed as the stereo cylinder 4 can provide another, 
preferably a smaller diameter than the stereo cylinder 4, without 
incurring the risk of producing the so called "Ghost images". 
FIG. 2 shows a part of the inking roller 6, which is in contact with the 
dosing strip 12a. The inking roller 6 has an elastic coating 15 and 
rotates in the direction of arrow 16. The dosing strip 12a has an edge 17, 
which faces the inking roller 6 and has a cylindrical surface. The axis 18 
of this cylindrical surface is also the axis of rotation 19, around which 
the dosing strip 12a swings by the angle alpha. 
FIG. 3 shows how the dosing element 12a can be disposed in a printing 
press. The inking roller 6 is disposed between two lateral walls 20 and 21 
of the printing machine. The axis 22 of the inking roller is rotatable in 
two bearings 23 and 24, which are attached to the lateral walls 20 and 21. 
The dosing strip 12a provides at each of its ends at the front side, a 
cover plate 25 or 26, in which the bearing pins 27 and 28 are attached 
stiff against torsion. The bearing pins 27 and 28 are disposed rotatable 
in the eccentrics or offset bearings 29 and 30. The eccentrics 29 and 30 
are disposed in the lateral walls 20 or 21 in such a way, that they can be 
rotated and fixed in the new position closer to or further away from the 
inking roller 6. Thus the dosing slot 31, which is formed by the inking 
roller 6 and the dosing strip 12a can be adjusted. 
The bearing pin 27 extends out beyond the lateral wall 20. On this 
extension a lever 32 is disposed fixed against rotation. The lever 32 is 
connected flexibly with a guide rod 34 by means of a bearing pin 33. The 
guide rod 34 is rotatably connected by its other end onto a bolt 35, which 
is fixed in a disk 36, which is rotated by a motor 37. The bolt 35 
provides a selective distance to the center of rotation of the disk 36, 
and this determines the angle alpha (FIG. 2), around which the dosing 
strip 12a is swingable. The rate of revolutions of the motor 37 determines 
the frequency with which the dosing strip 12a moves. 
A further possibility to dispose the dosing strip 12 as shown in FIG. 4. 
The dosing strip 12b has an edge facing the inking roller 6 which has an 
elastic surface, e.g. a cylindrical surface. This dosing strip is 
fashioned cylindrical at the side 39 averted from the inking roller 6, the 
distance R between the side and the axis of rotation 40 of the strip being 
constant. The dosing strip 12b lies with its cylindrical fashioned side 39 
on a correspondingly shaped bearing element 41, which is attached on a 
bearing carrier 42. The bearing element 41 is advantageously a friction 
bearing. The dosing strip 12b can be moved to and fro on the bearing 
element 41 by a drive 41a connected to the strip 12b at a spaced location 
from the center 40. In the course of this the dosing strip carries out a 
swinging movement with the cylindrical fashioned side 39, the center of 
rotation of which lies in the axis of rotation 40. In order to avoid the 
bearing element 41 from being polluted, the dosing strip 12b has a 
protecting sheet 43, which drains off the ink which has been wiped off by 
the dosing strip 12b around the bearing element 41. In FIG. 4 the two 
extreme positions of the swingable dosing strip 12b are represented (left: 
drawn line, right: dotted line). In order to be able to modify the dosing 
slot in this case, the bearing carrier 43 provides means which allow a 
lifting and lowering of the bearing carrier 42, as shown by the arrow 101. 
A further possibility to position the dosing strip 12 is shown in FIG. 5. 
Respectively two guide rods 44 and 45 are joined to the two front faces at 
the dosing strip 12c, which extends at least over an area along a 
generatrix surface line of the inking roller 6, the guide rods being 
attached by means of hinge pins 46 and 47. Guide rod 44 and 45 are 
connected each flexibly with two rocking levers 48 and 49 respectively, so 
that the guide rod 44 forms the link 50 with the rocking lever 48, and 
forms the link 51 with rocking lever 49, and guide rod 45 forms with the 
rocking lever 48 the link 52 and with the rocking lever 49 the link 53. 
Guide rod 44 is parallel to the guide rod 45. Rocking lever 48 and rocking 
lever 49 are parallel to the dosing strip 12c. The dosing strip 12c 
provides an edge 54 facing the inking roller 6 having a cylindrical 
surface and a cylinder axis 55 which is defined in this way. The cylinder 
axis 55 provides a distance from the link 46. Rocking lever 48 and rocking 
lever 49 are extended upwards in FIG. 5. At these extensions bearings are 
disposed, which are overplugged rotatable onto stationary axis 56 and 57. 
Axis 56 provides also the distance a from the link 50, and axis 57 from 
link 51 likewise. A pneumatical cylinder is attached to the link 54 in 
such a way that the rocking lever 49 can be put into a swinging movement 
around axis 57, as shown by arrow 59. This movement is transferred to the 
rocking lever 48 and the dosing strip 12c through the guide rods 44 and 
45. In the course of this the dosing strip turns around the axis of 
rotation 60, which coincides with the cylinder axis 55. The attachment of 
the axis 57 can be carried out in such a way, that its position can be 
slidable by axis 56, as shown by arrow 61, and which can be fixed in the 
new position. Through this displacement of the axis 57 by axis 56 the 
width of the dosing slot 62 between dosing strip 12c and the inking roller 
6 can be adjusted. 
In order to avoid that the edge 63 of the dosing strip 12d facing the 
inking roller 6 has to be treated very delicately and could be destroyed 
by wear, the dosing strip 12d can provide a protective coating 64 as shown 
in FIG. 6 the protective coating is made up of a supple plate, fashioned 
like a foil and is cased in on the one side of the dosing strip 12d into a 
number of lifting cogs 65 which are dispersed over the width of the dosing 
strip, and the protective coating is chucked over the edge 63 which forms 
the dosing slot 66 and is stretched tightly on the other side of the 
dosing edge 12d with a stretching strip 67 by screws 68, which are 
dispersed over the entire width of the dosing strip 12d If there is a too 
strong wear, the protective coating 64 has to be exchanged, the dosing 
strip 12d has not to be exchanged. This avoids additional costs for spare 
parts. 
Another possibility to move the area of the dosing strip 12e which forms 
the dosing slot 12e is represented in FIG. 7. The dosing strip 12e is 
composed of a supporting element 70, which is attached to a stable base 71 
and a supple plate 72, fashioned like a foil, which is stretched over the 
supporting element 70. The edge 73 of the inking roller 6 provides a 
curved shape. In the supporting element 70, disposed over its width, 
grooves 74 are worked in. On a continuous shaft 75 which is disposed in 
the flanges remaining between the grooves 74, whipping elements 76 are 
disposed stiff against rotation. The supple plate 72, fashioned like a 
foil provides cover plates 77 on both sides, which are attached to a 
pivotal element 76 by means of screws 78. A lever 79 is also attached to 
the shaft 75, fixed against rotation. On its side averted from the shaft 
75 it is joined to a pneumatic cylinder 81, which transfers an oscillating 
swinging movement onto the whipping elements 76 through the lever 79, as 
shown by the arrow 82. Thus the supple plate, fashioned like a foil is 
moved oscillating to and fro over the edge 73 facing the inking device 6. 
In addition to the embodiment shown in the FIG. 7, FIG. 8 shows a dosing 
strip 12f which provides a supple plate fashioned like a foil, which in 
its one end 84 is held stationary, the other end 85 being held by elastic 
stretching means 86. A supporting element 87, over the edge 88 facing the 
inking roller 6 of which the supple plate 83 fashioned like a foil is 
fixed on the front sides of the inking roller 6 at one rocking lever 89 
respectively, the rocking levers being attached flexibly to the axis of 
rotation 90 of the inking roller 6. The bar formed by the rocking lever 89 
and the supporting element 87 is swung oscillating around the axis of 
rotation 90 of the inking roller 6 by an angle alpha by means, which are 
not represented. This contributes as well to the object that the area of 
the supple plate which is fashioned like a foil and forms the dosing slot 
is continuously modified. In FIG. 8 two final position of the swinging 
movement are represented: The position on the left is represented in 
dotted lines, the position on the right is represented in drawn lines. 
In FIG. 9 the dosing strip 19g is composed of a bearing carrier 91, which 
provides a cavity 92 which forms a bearing shell, disposed on the edge 93 
facing the inking roller 6. In this cavity 92 a cylindrical rod 94 is 
positioned rotatable. the cylindrical rod 94 can be put into a rotating or 
an oscillating movement by non represented means, as shown by the arrow 
95. This also contributes to the object that always another area of the 
cylindrical rod 94 forms the dosing slot 96 together with the inking 
device. 
Experiments have shown that good printing results are obtained, if the 
cylindrically fashioned surface of the dosing strip 12 which forms the 
dosing slot provides a radius of about 0.3-1.5 mm. It has been stated as 
well, that in the case of a modification of the pushing pressure of the 
dosing strip 12 onto the inking roller 6 the thickness of the ink layer is 
modified only slowly. Thus by modifying the pressure a very refined 
gradation of the thickness of the ink layer can be obtained. The 
modification of the radius of the cylindrical surface of the dosing strip 
forming the dosing slot has a much bigger influence on the thickness of 
the ink layer, when the pushing pressure of the dosing strip 12 onto the 
inking roller 6 is maintained constant. 
Thus the optimal radius can be used as a function of he hardness of the 
surface of the elastic packing of the inking roller 6 and the viscosity of 
the ink. The movement of the dosing strip 12 in the described fashions has 
no influence on the produced ink layer, since the geometrical relations in 
the dosing slot remain the same. 
The experiments, furthermore, have shown that the dosing strip 12 is 
positioned preferably in approximately radial direction in relation to the 
inking roller 6. 
Offset printing machines as well as printing machines can be equipped with 
such inking devices; printing machines which use a different printing 
technique, especially those working with a hard printing block. 
While specific embodiments of the invention have been shown and described 
in detail to illustrate the application of the principles of the 
invention, it will be understood that the invention may be embodied 
otherwise without departing from such principles.