Ink dispensing means for printing presses

An inking unit disposed in the ink duct of a printing press includes dispensing elements for regulating the quantity of ink dispensed on the duct roller of the press and includes a plurality of blades disposed on linear adjusters for movement in the plane passing through the longitudinal axis B of the quantity-regulating dispensing elements and the line of contact between the dispensing edge thereof and the duct roller. Each blade is secured to a retaining pin on the adjuster by way of a securing aperture disposed perpendicularly to its bearing surface, and only minimal clearance, which can be very reduced in the direction of movement, is left between the pin and the securing aperture, so that when the ink gap closes, the blade of a dispensing element can automatically be aligned parallel by the dispensing edge bearing on the surface of the duct roller.

FIELD OF THE INVENTION 
The present invention relates generally to printing presses and more 
particularly concerns an ink dispensing unit for regulating the quantity 
of ink supplied from an ink duct to the duct roller of a printing press. 
BACKGROUND OF THE INVENTION 
Inking units for regulating the quantity of ink dispensed on a duct roller 
from the ink duct of a printing press are known to include zone dispensing 
elements which are adjustable relative to the duct roller and which have a 
dispensing edge cooperating with the duct roller to define a dispensing 
gap with the edge movable relative to the duct roller substantially 
radially and with the dispensing edge being disposed on a blade releasably 
retained on an adjuster. German patent No. 3 0303 774 discloses an inking 
unit of this kind. 
Such inking units are used in printing presses, more particularly offset 
presses, to ensure accurate and reproducible adjustment of ink quantity. 
Therefore, it is necessary to adjust the quantity of ink to different 
extents widthwise of the press and in zonally independent manner. The 
difficult part of this problem is the need for extremely accurate 
alignment of the various dispensing elements for very reduced ink layer 
thicknesses. The necessary outlay and the risk of the dispensing edge of 
the various dispensing elements being damaged should not be 
underestimated. If discrete dispensing elements or the blades on their 
adjusters are aligned inaccurately, what are known as "edge carriers" may 
arise which make it impossible to find an accurate zero setting for the 
particular dispensing elements concerned. Since in such cases the printer 
endeavors to engage the dispensing element completely with the duct roller 
by further adjustment in the particular zone concerned, damage easily 
arises because of increased wear. Nevertheless, it is an important 
objective to ensure accurate adjustment. 
According to the above-mentioned German patent No. 3 030 774, the 
dispensing edge is disposed on a push-shoe having spring steel plates or 
the like, on discrete ink-dispensing elements in the form of adjusters. 
The plates, with their hard resilient substance, form the dispensing edge 
and are secured in a resilient embedding composition. Also, the 
composition is formed with a recess behind the dispensing edge. This 
dispensing element reduces the wear to some extent because of the 
increased strength of the dispensing edge and because of the resilience 
thereof. Ease of service is improved by simple replacement of the shoe 
which can also latch in the ink-dispensing element by way of cast-on 
protuberances. 
The alignment of the shoe relatively to the adjuster is not variable in the 
ink dispensing element just described--i.e., the dispensing edge cannot be 
adjusted independently relative to the adjuster. Errors of manufacture are 
therefore fully transferred to the assembled unit and affect the accuracy 
of ink dispensing. In all, the ink-dispensing element suffers less from 
wear but does not ensure that the adjustment of the thicknesses of thin 
ink films is always accurate. Consequently, accurate alignment and 
equalization of the dispensing edge of the various dispensing elements 
relative to one another causes problems just as severe as adjustments 
relative to the duct roller. 
For example, if a slightly inclined ink-dispensing element was to be 
operated at zero ink film thickness, the dispensing edge would have to 
bend in order to interrupt the supply of ink completely. This bending is 
possible but sets a wrong zero for the opening of the dispensing gap, for 
when the ink-dispensing element returns, such gap is initially opened only 
on one side, with the result of underinking. Also, the power consumption 
relative to the duct roller is such that it bends by something like 10 
times the permissible gap for minimum inking between the dispensing edge 
and the roll surface. Consequently, independent widthwise adjustment of 
the dispensing elements cannot be ensured. 
OBJECTS AND SUMMARY OF THE INVENTION 
It is therefore the primary object of the present invention to provide 
means for regulating the quantity of ink dispensed on a duct roller such 
that the outlay needed to align the ink-dispensing elements relative to 
the duct roller and the force applied by the dispensing element to such 
roller is reduced decisively with minimum ink guidance, the dispensing 
edge being adapted to be aligned readily and totally on the duct roller 
surface. 
In carrying out the present invention there is provided an inking unit 
disposed in the ink duct of a printing press for regulating the quantity 
of ink dispensed on the duct roller of the press including a plurality of 
zone dispensing elements adjustably mounted relative to the duct roller 
and which have a dispensing edge cooperating with the duct roller to 
define a dispensing gap, with the dispensing elements being movable 
relative to the duct roller substantially radially, the dispensing edge 
being disposed on a blade releasably retained on an adjuster, and 
characterized in that the blade is immobile and is mounted on the 
dispensing element for movement in a plane determined by the direction of 
dispensing element movement and by the duct roller generatrix contacted by 
the dispensing edge. Preferably, the blade is mounted with clearance 
around a fulcrum disposed perpendicular to the longitudinal axis (B) of 
the dispensing element and at least one surface on which the blade bears 
is so disposed at a place within its retaining means that the blade 
fulcrum (C) has limited provision for displacement. 
The inherently rigid construction of the blade ensures that the position of 
the dispensing edge relative to the drive of the dispensing elements is 
always accurate. Since the blade can rotate on the dispensing element, 
merely moving the blade towards the duct roller is sufficient to align the 
dispensing edge relatively to the duct roller surface. There is no need 
for manual fine adjustment. It has been found that if the blade is in the 
form of a rockable element, hydrodynamic effects deriving from the ink do 
not impair the alignment of the dispensing edge. The blade is adjusted to 
an equilibrium of forces arising from the pressure in the ink drawn 
through the ink gap. In the arrangement described, the center of the 
dispensing edge is always at the correct distance from the duct roller 
while the corners of the dispensing edge are at the same distance from or 
at appropriately different distances from the duct roller surface. 
However, the opening available for ink conveyance always has the same area 
--i.e., the quantity of ink conveyed through the gap over the width of a 
zone is always the same. Theoretically, the dispensing edge can become 
skewed only because of manufacturing inaccuracies in the region of the 
blade mounting; however, because of the flexibility feature this 
consideration is virtually negligible. Inaccuracies are very reduced and 
are virtually ineffective so far as ink distribution is concerned, since 
because the distribution is effected transversely of the inking unit, the 
layer or film differences still present on the duct roller within any 
single inking zone are smoothed out again substantially completely. 
One very important effect of the means disclosed is that even though the 
ink-dispensing elements of this kind become skewed relatively to the duct 
roller surface, no "edge carriers" can arise. When the dispensing elements 
move in--i.e., when the ink gap closes--the projecting corner of the blade 
bears on the duct roller surface, whereafter because of its rotatable 
mounting the blade aligns itself until the dispensing edge is in complete 
engagement with the duct roller surface. 
As a rule, no particularly great accuracy is required for the mounting of 
the blades on the dispensing elements, since all that is necessary is to 
provide for the blade to have a bearing or support surface enabling the 
blade to align itself around a pivot or fulcrum. Since the blade can 
therefore be arranged relatively loosely, the blade is readily 
interchangeable. Indeed, the blade can be replaced in the ink duct without 
any need to dismantle the dispensing element therefrom. Very substantial 
advantages are therefore provided as regards the cost of assembly and 
fitting and more particularly the accuracy of adjustment of the 
ink-dispensing elements. 
These and other features and advantages of the invention will be more 
readily apparent upon reading the following description of a preferred 
exemplified embodiment of the invention and upon reference to the 
accompanying drawings wherein:

While the invention will be described and disclosed in connection with 
certain preferred embodiments and procedures, it is not intended to limit 
the invention to those specific embodiments. Rather it is intended to 
cover all such alternative embodiments and modifications as fall within 
the spirit and scope of the invention. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Turning now to the drawings, FIG. 1 shows the basic relationship of the ink 
dispensing unit of the present invention in association with an ink duct 1 
and an ink duct roller 2. A quantity-regulating element 3, hereinafter 
called a dispensing element, is secured with its drive 4 in the ink duct 
1. The drive 4 is directly coupled by a spindle 5 to an adjuster 6 movable 
radially or substantially radially relative to the roller 2. A blade 7 is 
disposed on the adjuster 6. Movement of the adjuster 6 moves a dispensing 
edge 8 at the front of the blade 7 relative to the roller 2 so that an 
inking gap 9 is defined between the duct roller surface and the edge 8. 
FIG. 2 shows in plan view the relationship of the dispensing elements 3 
generally perpendicular to the axis A of the roller 2. The elements 3 with 
their drives 4 are disposed one beside another on the duct 1, the 
longitudinal axes B of the elements 3 being disposed substantially 
parallel to one another, and the relationship is such that the blades 7 
touch one another. Preferably, the adjusters 6 are narrower and do not 
touch one another. Securing screws are provided to determine the alignment 
of the elements 3. The screws are engaged in tapped apertures and retain 
the elements on the bottom of the ink duct 1. 
When the elements 3 are aligned relative to the surface of the roller 2, 
the screw-threaded connection between the elements 3 and the ink duct 1 is 
an important factor. As the retaining screws just referred to are finally 
tightened, the elements 3 experience a torque which affects their 
alignment. Consequently, it is a very elaborate business to adjust the 
longitudinal axis B of the elements 3 accurately perpendicularly to the 
duct roller axis A. If the dispensing edge 8 had to be adjusted by way of 
alignment of the elements 3, the assembly and subsequent replacement of 
the discrete elements 3 would be very difficult. According to the 
invention therefore, and as will be described hereinafter, the blade 7 is 
removably secured to the adjuster 6 in a non-rigid manner. 
The securing of the blades is basically the same in all the embodiments 
described and is shown just once in the enlarged cross-section of FIG. 3. 
A retaining pin 10 is riveted or otherwise secured in the adjuster 6 so as 
to be perpendicular to the major dimension thereof. The pin 10 has 
screw-threading and a nut 11 retains the blade 7 on the pin 10 and 
prevents the blade 7 from tilting. For improved assembly the nut 11 is 
preferably formed with a transverse slot; it can then be screwed into a 
recess 12 formed at its base with an opening 13 for guiding the blade 7. 
The recess 12 and opening 13 are perpendicular to the bearing surface 14. 
The shape of the opening 13 and its dimensions relative to the pin 10 will 
be described in detail hereinafter since they are the main elements 
determining the movement pattern of the blade 7. An insert such as a cup 
spring can be provided between the nut 11 and the blade 7 to obviate 
clearance in the position of the blade 7 and to compensate for 
manufacturing inaccuracies. However, the nut 11 can be placed on the pin 
10 without any insert so tightly over the blade 7, then secured, for 
example, by sticking, as to secure the blade 7 directly. Consequently, the 
blade 7 can then move freely on its bearing surface 14 but cannot tilt 
from its full-surface engagement with the adjuster 6. After assembly the 
recess 12 is filled with a potting compound and protected against the 
entry of ink. In the discussion that follows, a description will be given 
of how, by displacement of the rotational axis C of the blade 7, different 
variants are possible for the cross-sectional shape of the blade 7 in its 
major dimension and of the shape of the apertures 13. 
As a basic starting point, it may be assumed that the blade 7 is to be 
aligned on the surface of the roller 2 only when it is required to close 
the gap 9. The clearance in the mounting is to be used in the opening of 
the gap 9 by the blade 7 in this case oscillating like a balance beam 
relative to the adjuster 6 as a result of being acted on by the 
hydrodynamic pressure of the ink. The flow cross-section of the gap 9 
always corresponds to the necessary opening cross-section for a particular 
quantity of ink, since the main parameter for ink quantity is the position 
of the adjuster 6 or of its aligning surface. A very simple variant on 
this point is shown in FIG. 4. 
The opening 13 is in the form of a simple aperture 15 having relatively 
considerable clearance relative to the pin 10. The aperture 15 can widen 
forwardly so that a plane bearing surface 16 is formed. The blade 7, when 
aligned on the roller 2 by the pressure of the ink, normally bears on the 
surface 16; however, it can deviate in all directions since the rotational 
axis is disposed behind the edge 8. 
FIG. 5 shows another embodiment wherein the rotational axis C has been 
displaced to the rear edge of the blade 7. Accordingly, the blade 7 has a 
convex rear surface 17 disposed opposite the edge 8. The blade 7 is 
adapted to bear by way of the surface 17 on a rectilinear bearing surface 
18 of the adjuster 6. A retaining pin 10 is disposed therein to retain the 
blade 7 on the adjuster 6. Also, the blade 7 is formed with a slot 19 
through which the pin 10 extends. The blade 7 may be secured to the 
adjuster 6 in the manner discussed above (see FIG. 3). This embodiment can 
also be altered in various ways. For instance, the convex surface can be 
on the adjuster 6 instead of on the blade 7, in which event the rear 
surface 17 thereof is a plane surface. Similarly, the blade 7 can bear by 
way of a plane rear surface 17 on a cylindrical pin in the adjuster 6. 
In addition, the clearance in the mounting of this embodiment can be 
reduced very considerably. This leads to some complication of the 
construction of the dispensing elements 3 since they must be made to 
higher standards of accuracy, but it may be very important that the blades 
7 can in this case be mounted without longitudinal clearance. A second 
underlying idea starts from the fact that the blades 7 must always be 
guided accurately in the longitudinal direction but that they should be 
able to adjust their alignment relative to the longitudinal axis B as 
regards their angular position and their position transversely of the axis 
B. Once this adjustment has been made, their alignment should be retained 
as far as possible and in any case at least until the next adjustment. 
An example will now be described with reference to the embodiment which is 
shown in FIG. 6 and which represents a position between the two underlying 
ideas set out in the foregoing. Referring to FIG. 6, the blade 7 is formed 
with a slot 19 as its securing aperture. Its rear surface 17 is 
rectilinear and does not contact the adjuster 6. The adjuster is formed 
near its bearing surface 18 with a recess such that a retaining 
protuberance 20 remains at each outer edge of the surface 18. Preferably, 
a spring strip 21 is clamped between the protuberances 20 and the 
convexity of the spring strip 21 acts on the blade rear surface 17 so 
that, by way of the rear boundary surface of the slot 19, the blade 17 is 
biased towards the pin 10. The blade 7 is in this way devoid of 
longitudinal clearance but can make rotating and sliding movements. In any 
case, when the gap 9 is open the spring strip 21 restores the blade 7 to a 
neutral normal position. The normal position depends, in respect of its 
alignment relative to the axis B of the elements 3, upon the manufacturing 
accuracy of the arrangement, more particularly upon the centering of the 
spring strip 21 relative to the pin 10. 
FIG. 7 shows another embodiment of a blade 7 which is movable on the 
adjuster 6 and which with present day knowledge can be regarded as the 
most advantageous construction economically, design-wise and process-wise. 
The particular point embodied in this case is that clearance in the 
mounting in the direction of movement of the adjuster 6 is minimized but 
clearance transversely to the direction of movement is adapted to 
circumstances for positional compensation. Accordingly, a guide pin 22 is 
disposed on the adjuster 6. The pin 22 has a closely toleranced surface. 
The blade 7 is formed with a guide slot 23 having the following 
dimensions: parallel to the edge 8 it is approximately 1 mm larger than 
required for the diameter of the pin 22; the width of the slot 23 in the 
direction of the axis B is equal to the diameter of the pin 22. The slot 
surfaces which are parallel to the edge 8 are plane guide surfaces 24 and 
must be substantially parallel. It will be understood, of course that the 
blade 7 must be placable relatively readily on the pin 22 and must remain 
mobile thereon. Clearance 25 for movement relative to the adjuster 6 is 
therefore also necessary at the rear. Retention can be merely the kind of 
securing shown in FIG. 3. When the adjuster 6 moves, the blade 7 always 
follows the "instructions" of the drive 4, but the blade 7 is mobile 
relative to the adjuster 6 and, therefore, to the element 3. 
In all the various embodiments, the blade 7 must be treated in the zones 
near the edge 8 for adaption of the side edges of the blades 7 to one 
another. The cross-sectional shape of FIG. 8 is illustrated in the form in 
which it appears when two blades 7 contact one another. Preferably, the 
blade side edges 26 taper conically to the rear. Ideally, a cylindrical 
sealing surface 27 should be provided on a short portion of the side edges 
26 near the dispensing edge 8 to ensure optimum mobility and 
sealing-tightness. In practice, however, these sealing surfaces 27 are 
lapped plane over a length of approximately 2 mm and given a low-friction 
coating. 
The overall space is determined by the blades 7 disposed laterally of the 
particular blade 7 under consideration. Consequently, the rear corners of 
the blades 7 must be able to move laterally in addition to the blade 7 
being rotatable, since as it rotates the blade 7 bears on the surface 27. 
Accordingly, the blade 7 is arranged to be retained with adequate 
clearance adapted to take up the maximum possible lateral movement of the 
blade 7, and the width thereof decreases continuously to the rear from the 
edge 8. A wedge-shaped movement gap 28 is therefore left between any two 
blades 7. 
A general description will be given hereinafter of the operation of the 
self-adjusting blades 7. When a dispensing element 3 with drive 4 is 
assembled in an ink duct 1, the alignment relative to the roller 2 must be 
maintained substantially at right angles. The blades 7 are then brought 
into lateral engagement with one another. Also, in assembly, as is 
conventional with elements 3 of this kind, a sealing compound is 
introduced near the adjusters 6, to prevent the entry of ink into the 
drive 4 or other parts of the dispensing elements 3. 
After assembly each dispensing element 3 can be zero adjusted 
independently. To this end, the adjuster 6 is moved by the drive 4 towards 
the roller 2. If the element 3 is not aligned at true right angles to the 
roller 2 or if the blade 7 is not disposed straight on the adjuster 6, one 
of the corners of the edge 8 first contacts the roller 2. As previously 
discussed, in the known version of the rigid adjuster, this contact is 
known as an "edge carrier". Conventionally, it has not been possible to 
have accurate zero adjustment of the adjuster in this zone. 
In the ink dispensing means according to the present invention, however, 
the blade 7, being mobile, turns on the adjuster 6 until the edge 8 is in 
fully flush engagement with the surface of the duct roller 2. Only then 
has the proper zero adjustment of the element 3 been reached. This 
adjustment can be retained mechanically or electrically. In a position 
thus adjusted the supply of ink to a subsequent inking unit is stopped 
completely for the particular inking zone concerned. The elements 3 can 
then be adjusted seriatim for the entire ink duct 1. 
However, depending on the nature of the blade mounting, various movement 
patterns may be operative in the alignment on the duct roller surface. In 
the versions shown in FIGS. 4-7 there is a superimpositioning of 
movements. Since the fulcrum of the blade 7 is disposed behind the edge 8, 
a pure rotation at the edge 8 would lead to a cross-movement or 
cross-displacement. Such cross-displacement must be compensated for by a 
sliding movement of the complete blade 7. What happens in practice is that 
because the blade 7 is retained laterally between the adjacent blades 7, 
the blade 7 does not rotate around the bearing on which it bears 
momentarily but moves relatively to the mounting thanks to the available 
clearance. The relative movement, called a sliding movement, means that 
the blade side edges 26 move relatively to one another. Consequently, the 
blades 7 must not be pointed at their front corners nor be at true right 
angles to the edge 8 on their side edges but must be shaped in the manner 
hereinbefore set out. 
In another more theoretical than practical but theoretically ideal variant, 
the relative movements described disappear. The starting point for this 
embodiment is that the fulcrum C of the blade 7 is placed in the edge 8. 
To this end, the entire rear boundary surface of the blade 7 can be an 
arcuate articulation surface 29. The surface 29 bears in another arcuate 
bearing surface 30. When the blade 7 turns, the corners of the edge 8 move 
in an orbit corresponding to the surface 29 around the imaginary fulcrum 
passing through the edge 8. This ensures that the blades 7 do not move 
beyond the lateral boundary operative in the normal position. 
Consequently, a blade 7 of this shape cannot anywhere collide with an 
adjacent blade 7. However, in response to substantial rotation--very 
unlikely to arise in practice--that corner of the edge 8 which retreats 
behind the normal line moves away from the adjacent blade 7, a gap opening 
between the two blades 7. In extreme conditions, therefore, ink might 
penetrate between the adjusters 6. This might disturb operations, although 
there is the seal between the elements 3. On the side on which the corner 
of the dispensing edge projects beyond the normal line, sealing tightness 
in respect of the adjacent blade 7 is ensured by the arcuate surface 29. 
Arcuate surfaces 29, 30 of this kind are difficult to produce for 
practical use. Accordingly, to ensure a clearance-free mounting, a 
compression spring 31 must press the blade 7 on to the surface 30. 
Absence of clearance can also be ensured by using a counter-bearing surface 
to the articulation surface of the blade 7. For instance, the blade 7 can 
be machined from a cylindrical blank having the diameter of ink zone 
width, a cylindrical mounting or base serving as bearing and the 
dispensing edge being disposed on a diameter on the end face opposite the 
mounting. 
The invention described can of course be embodied by other variants. For 
example, the bearing position considered could be shifted to before the 
dispensing edge. However, this would considerably complicate operating 
conditions.