Inking device

This invention relates to a mechanism and procedure designed for feeding ink to typographic, offset, flexographic and other presses. This invention is characterized in that the inking mechanism comprises a very high precision rotary drum which homogenizes and supplies, while micrometrically proportioning, one or several films of inks of different colors or kinds. This procedure is distinguished by the fact that the film or films created is/are directly ready for printing and particularly well suited for the simultaneous handling of different colors or kinds of ink.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an inking procedure and mechanism designed for 
typographic, offset, flexographic, lithographic and other printing 
presses. 
2. Description of the Prior Art 
The inking mechanisms used to equip nearly all printing presses are 
analogous to one another and make possible only the use of one ink per 
printing. 
They are constructed and operate as follows: 
A duct serves as reservoir and ink source, and flow is obtained from it 
through the interplay between the deformation in a flexible steel blade 
and a metal cylinder, called the ink drum, against which the blade 
presses. The ink comes into play between the blade and the ink drum and 
forms as its surface a film of varying thickness depending on the pressure 
applied to the back of the blade by control screws. 
A set of flexible rollers, alternated with metal cylinders, transfers and 
modifies the ink film to make it ready for inking. Depending on the 
manufacturer and on the density and quality of inking desired, the number, 
diameter and arrangement of the rollers and cylinders may vary 
significantly. 
According to this principle of inking, it is possible only approximately to 
control the thickness of the ink film in zones about 20 mm to 40 mm in 
width. The advance of the ink drum is generally variable and adjustable. 
The film emerging from the duct is relatively thick and not suited to high 
quality printing; it is improved by each distribution roller which thinly 
spreads, laminates, mixes and homogenizes it. The distributing cylinders 
take part in and complete this action; they are called "distributors" 
because of their axial and rotary movement. Area by area, they even out 
the thickness of the film and prevent annular ridges which might result 
from ink surface tension. 
The film inking the printing portions of presses must be perfectly even and 
of constant thickness in a given zone. The acceptable tolerance is of the 
order of 2 to 3 microns above or below the target thickness. 
Depending on the holder, the type of printing and various other factors, 
the ink forming the film must have a particular rheology, which is 
determined by its ingredients, possible additives, and the mechanical 
action of the inking device. To a large degree, the quality of the inking 
determines the quality of the ultimate print. 
Conventional inking mechanisms in general make it possible to meet such 
requirements. In addition to their bulk and clumsiness, however, they 
present a number of drawbacks: 
imprecise control of ink film thickness in narrow zones, making the 
juxtaposition of flat tint printing with small characters quite tricky; 
unnecessarily excessive ink consumption when the surface area to be printed 
is negligible in comparison with the overall printing surface of the 
machine. This consumption becomes very high when there are a number of 
short printing runs to be made in succession using different colors; 
when printing is first started up, the ink balance is obtained only after a 
certain number of copies have been printed, resulting in paper waste. 
Moreover, the basic principle of this type of inking makes it unsuitable 
for handling different colors of ink in a single printing. Indeed, the 
so-called distributor cylinders, those which move axially and in rotation, 
rapidly mix the inks together, and the duct does not allow for the release 
and control of narrow flows of inks of different colors. 
In an effort to overcome this limitation, several patents have been filed. 
They all retain the same printing principle and, by means of more or less 
different methods, suggest the creation of zones of discontinuity at the 
junctions between the different-colored inks by using circumferential 
grooves in the axially-moving rollers or the rollers working in tandem, or 
by scraping up the residual ink which remains after the mixing action of 
the axially-moving rollers. These methods are but palliatives, and are ill 
adapted to successive runs which may differ greatly from one to the next 
and often are quite short in numerical terms. Quite apart from discussion 
of the duct, the sole fact of having to make special "distributor rollers" 
for each different press run gives rise to additional work for the 
printer, work which in the vast majority of cases is not justified by the 
time savings achieved and, in practice, eliminates the advantages of this 
method. 
Indeed, a printer who desires a multicolored printing is required to treat 
each color in succession, one after another, which does not require as 
many passes through the press as it does colors except in three- or 
four-colored prints using plates where the overlaying of the three primary 
colors theoretically makes it possible to achieve any tint. However, this 
type of printing is reserved for specific types of prints and still 
requires 3 or 4 press runs. 
This de facto situation makes it difficult to produce multicolor prints at 
a low cost. 
French Pat. Nos. 1.275.206, 1.341.700, and 2.194.576 have proposed 
solutions aimed at simplifying conventional inking devices by eliminating 
almost all elements of the sequence of distribution rollers and cylinders. 
The basic idea in these patents is to create a single, laminated and 
proportional ink film by pressing together two cylinders, one of them 
metal and the other covered by a flexible material, so as to ink the 
offset plate directly. This procedure allows neither for zone-by-zone 
control of the film thickness nor for the possibility of partitioning off 
inks of different colors. This system is perhaps sufficient for use in 
offset work to handle one color or kind of ink per printing, where in 
theory each point on the plate takes the same quantity of ink, since 
nearly all offset presses in use are equipped with inking devices with 
zone-by-zone control screws similar to those used in typography. 
In typographic printing, especially in the case of the platen press where 
pressure control is rather delicate depending on the lubrication of the 
printing parts and is closely correlated with the inking, it is essential 
to control the thickness of the ink film zone by zone. 
Depending on their kind or color, inks have different densities and 
rheologies, which require different thicknesses in order to obtain a given 
inking. 
To devise an offset or typographic inking mechanism able to handle several 
inks at once, where each film must be inked individually, it is necessary 
to take the above factor into account and provide the capacity for 
adjustment in narrow zones, this so as to make it possible for the printer 
to use narrow "ribbons" of ink. 
SUMMARY OF THE INVENTION 
This invention relates to an inking mechanism used to create one or several 
ink films, suited for the inking of the printing parts directly, on a 
metal cylinder serving as an ink bed. The thickness of the film(s) in 
question may be controlled micrometrically, one narrow zone at a time. 
This device makes it possible to eliminate the series of "distribution" 
rollers and, within the high precision rotary duct, to introduce different 
colors or kinds of ink directly in different compartments. This cylinder 
is preferably cylindrical and inks the inking rollers, which in turn then 
ink the printing parts. 
Another form of the invention makes it possible to eliminate the inking 
rollers and directly ink the printing parts with the help of a special 
metal cylinder which acts as a heat radiator and is covered by a hard 
elastomer whose flexibility is virtually uninvolved in the lamination of 
the ink. In this arrangement, separators may be made of self-lubricating 
flexible materials, such as teflon, and the elastomer coating on the metal 
cylinder may be protected by a varnish so as to protect it at the places 
where the ink separators are operating. 
The metal inking bed may be retained in the device and incorporate a 
cylinder coated with an elastomer for transferring the ink film to the 
printing plate, with the rolling by of this cylinder corresponding 
strictly to that of the printing plate holder so that the inking recurs at 
the exact same locations with each rotation of the cylinder.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The frame of the inking mechanism is made up of two side plates 1, rigidly 
interconnected by a keyed crossmember 3. The frame supports two movable 
side plates 2 which pivot when actuated by two eccentrics 13 controlled by 
a cross shaft which also supports a control lever 14. The function of the 
control lever 14 is to stop the inking of the inking rollers 11 by 
removing the ink drum 4 from contact with rollers 11. The ink drum 4 
between the side plates 2 receives the ink film. It has a single axle 
supported by two twin-race ball bearings 28 whose taking-up of slack is 
automatic. The interior of the drum features fins 30, shown in FIG. 2, for 
use in dissipating the calories produced by the surface heating 
attributable to the lamination of the inks and to the friction of the 
separators 16 which keep the inks apart from multicolor printing. A sleeve 
29, plated with a few tenths of a millimeter of finely polished chromium 
to increase the adhesion of the ink and its spreading, is used to cover 
the fins 30. Before polishing, this sleeve 29 is carefully trued up. The 
movement of the gear train 12, shown in FIG. 1, is induced by that of the 
platen, and causes movement of the drum 4. The rollers 11 are inked 
directly from the drum 4, where the ink film is re-established with every 
rotation. 
A holder frame 24A, shown turned upwardly on its back side in the second 
embodiment in FIG. 4, is provided for the assembly of blades 25A which 
control or doctor the ink, and their set screw 26A is attached with the 
help of two abutments made of hardened and ground steel. This frame is 
removable for cleaning purposes. 
An adjustment screw and counterscrew frame 20, shown in FIGS. 1-3, is 
firmly secured by screws to the holder frame 24 in the first embodiment. 
Screw 18A in the second embodiment in FIG. 4 acts on the stepdown lever 
19A which moves the blade 25A and makes it possible to adjust it. Each 
blade 25A is adjustable individually in the first embodiment in FIGS. 1-3. 
The holder frame 24 and screw frame 20, shown in FIGS. 1-3, are machined 
from a hardened and ground steel with high mechanical strength. 
Each blade 25, shown in FIGS. 2 and 3, is made of a highly processed steel, 
such as spring steel, which is both hard and elastic. The thirty-five 
blades 25 shown in FIG. 3 making up the device are hardened and ground 
true on all their surfaces. 
Another piece 31 shown in FIG. 3 of treated steel serves as the squaring 
reference for the blades 25. Piece 31 is firmly attached to the holder 
frame 24 and ground true in place for squaring purposes. 
The operation of mounting the blades 25 on their holder frame 24 calls for 
the greatest care. Before mounting, the assembly of the elements is dipped 
in a solvent and dried with compressed air. 
The first blade 25 is placed on the squaring reference piece 31, shown in 
FIG. 3, and is attached by means of a dynanometric key; the next blade 25 
is placed adjacent to the first blade 25 before attachment and so on, 
until the last blade 25, itself retained by a locking piece 32, shown in 
FIG. 3, holds the entire blade assembly at its full length and prevents 
any deformation. A general sealing joint 21, shown in FIG. 2, is put in 
place to protect the mechanical adjustment assembly from impurities. The 
blades 25 are contiguous and can move with respect to one another without 
changing their relative settings. They are impermeable to ink and remain 
in the set position against the stop 23, shown in FIG. 2, which keeps all 
the blades 25 at the same setting. These individual blades 25 taken 
together constitute a single blade 25 which is trued up and finely ground 
on its working edge against the ink drum 4 with which it cooperates. 
The ink carried by the drum 4 is laminated and homogenized and forms a film 
suitable for printing, which is taken in a conventional manner from the 
ink reservoir 27, shown in FIG. 2, contained between the drum 4 and the 
blades 25. Control of the thickness of the ink is variable in one micron 
increments, with one turn of the screw 18 or 18A corresponding to about 10 
microns. 
An eccentric 9 and its control lever 8, both shown in FIG. 1, regulate 
inking in general, by acting through the elastic deformation of the two 
movable plates 2 which support the drum 4 to provide a course adjustment 
thereof. 
A set of positioning screws 5, shown in FIGS. 1 and 3, makes it possible to 
place the reservoir 27 precisely with respect to the ink drum 4. 
The blade assembly 25 is set at its given position at a distance of about 5 
microns from the drum 4, which the assembly must not contact so as to 
avoid uneven wear on the blades 25 and heating harmful to the device. 
A movable separator 16 and the support screw 17 thereof, both shown in 
FIGS. 1-3 ensure that the different inks are kept apart. A pressure roller 
10, made of rubber with a hardness of about 70 Shore units, evens out the 
ink film in the event that it contains any impurities. 
The separators 16 are made either of rigid or semirigid material such as 
polyurethane, high molecular weight polyethylene, etc., lubricated during 
printing by a wick or other known process in order to limit heating and 
wear, or are made of a microporous material which, before use, is 
impregnated with wax or with a lubricating fluid, perhaps ink repellent, 
such as silicone. Water is also a good ink repellent. 
The following is an example of a separator 16 which causes very little 
heating. 
A cardboard felt, weighing about 500 g per square meter when 1 mm thick, is 
impregnated with a solution containing about 15 percent of dry extract of 
blocked polyurethane or epoxy resin, in order to fix the fibers, and is 
then re-impregnated with wax having a melting point of about 90.degree. C. 
After cooling, the cardboard felt for the separator 16 is cut and finished 
by machining. Next, the parts of the separator 16 in contact with the 
blade 25 and the drum 4 are coated by immersion in a hardenable mastic 
which will counteract the pressure of the laminated ink and ensure 
complete sealing. 
This mastic is based on wax and plastic resin. 
Another form of the invention relates to a simplified manufacture of the 
inking mechanism and, for the most part, is well suited to the 
construction of semiprofessional offset machines. 
In this version, regulation of the ink flow in narrow zones is eliminated 
and the inking blade assembly 25, shown in FIGS. 1-3, is replaced by a 
single, rigid blade 25A, which is trued up precisely and general 
adjustment of which is obtained in the same manner as that described for 
the contiguous blades 25. 
When this procedure is followed and inks of different colors or kinds are 
being handled simultaneously, it is essential to be able to modify the 
pigment density of the inks depending on the color density of the tint to 
be obtained. 
In effect, in one and the same tint, the color density is variable in 
direct correlation with the pigment density of the ink. 
By way of example, one simple method which makes it possible to vary the 
pigment density of the ink at will is described below. 
All the inks used will have a high pigment concentration and may be diluted 
with a conventional transparent additive depending on the color density to 
be obtained. The basic adjustment of the inking will be carried out on the 
most dense tint and the other tints will be modulated from that starting 
point. The reverse process of making the inks more dense may also be done 
by adding pigment of the same kind to those inks which require such 
additional thickness. A densitrometer makes it possible to make these 
adjustments easily and precisely. 
Various kinds of mechanisms are used to supply water to offset presses. 
Some devices are used mainly for semiprofessional machines and directly mix 
water with the ink. Most professional machines, however, have one or more 
wetting rollers (not shown) which supply water to the plate (not shown) as 
required. Some of these rollers are driven in rotation and in oscillation. 
In most cases, and depending on the nature of each ink, it is very 
difficult to prevent the water from migrating slightly into the ink. Thus, 
if the simultaneous processing of different colors or kinds of inks is 
desired, it is essential to eliminate movement in oscillation by the 
wetting rollers, so as to keep the water, already mixed with one color of 
ink, from being brought into contact with ink of a different color. 
Numerous particularly interesting applications of this procedure are 
possible, and may be obtained by incorporating, in existing typographic or 
offset presses, inking devices which are less bulky, more precise and 
practical to use than those originally provided, and also make it possible 
to work simultaneously with several inks of different colors or kinds. 
Apart from the wide range of possibilities open to this procedure in all 
traditional press arrangements, there is a vast field for this invention 
in the printing of labels, paper, wrapping material, etc. 
The ability to ink, in given zones depending on the item printed, without 
having to ink the entire machine, makes it possible to save quite 
substantial amounts of ink, especially when a succession of short press 
runs in different colors is involved and when the surface to be printed is 
small in comparison with the full printing surface of the machine. 
The foregoing preferred embodiments are considered as illustrative only. 
Numerous other modifications and changes will readily occur to those 
skilled in the art of printing and, consequently, the disclosed invention 
is not limited to the exact constructions and operations shown and 
described hereinabove.