Note: Descriptions are shown in the official language in which they were submitted.
-'~ 2151843
Dampenin4 Units Of Offset Printinct Presses
The invention described herein concerns the traditional dampening units of
offset printing presses and relates to a procedure designed to transform the
principles and mode of their operation. The purpose of these conversions is to
endow dampening units modified according to the invention with
characteristics and operational possibilities similar to those possessed by
dampening units of recent design, which function according to principles and
with a degree of precision that make it possible to obtain easily and
instantly
correct ratios of water to ink and close integration of the dampening and
inking
processes, the determining parameters which have enabled this method of
printing to be developed. The principle characteristic of this conversion, the
subject of the invention, is that the design and construction of the modified
dampening units re-incorporates the main components and mechanisms of
the original dampening unit, in order to retain their perfect geometry with
respect to the other mechanisms of the press with which they work in harmony
to perform correctly all the operations for dampening the printing plate. This
procedure makes it possible to produce, at low cost, dampening units which
are as totally integral to the press as the original dampening units of which
they are the direct issue and to incorporate, directly and at reduced cost
during manufacture of these presses, all the conversions which are the
subject of the invention using means similar to those proposed for the
application of the invention.
In its various forms, the invention makes it possible to choose the mode of
continuous film dampening which is best suited to the types of printing press
to be modified, sheet by sheet or continuous, as a function of their inking
rate
and the printing jobs that they carry out.
At present, the great majority of offset printing presses are equipped with
conventional dampening units. These units, which are relatively primitive in
design, perform their overall function of dampening an offset printing plate,
but
possess certain serious weaknesses in the mode and precision of their
operation. Their dampening water feed is by alternating flow from a reservoir
constituting a general supply. The rollers which convey the dampening water
A
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to the printing plate are covered with a sleeve of spongy fabric designed,
once
they are wetted, to carry a reserve of a considerable quantity of dampening
water, reasonably well distributed throughout the sleeves, but in very
approximate quantities. Given a reserve of this nature, it is a matter of
trial and
error to create an even film having a thickness which varies by an amount of
the order of one or two microns, is precisely defined and can be controlled
from one type of print to another. The absence of accurate means of control of
the thickness of the water film, added to the excessively long response time
of
a dampening unit when the thickness is to be modified means that it is
impossible to work with precision and it is difficult to achieve and maintain
an
acceptable ratio of dampening water to ink. Furthermore, this delicate
equilibrium has to be re-established each time the press has been stopped,
entailing a waste of both printed paper and time which is by no means
negligible. At each change of ink colour and each long stoppage, the sleeved
rollers become impregnated with greasy ink and have to be carefully cleaned.
This operation, which is tedious for the printer, engenders considerable loss
of
time, involving as it does the dismantling and cleaning of these rollers and
their re-fitting on the press. Another drawback of these sleeved rollers is
that
they disintegrate little by little and the fibres that they lose become stuck
to the
rollers of the inking unit and impair printing quality.
The consequence of all these negative aspects is that at present the majority
of printing presses destined for the industrial production of work demanding
optimum performance and a high and constant level of quality are almost all
equipped with dampening units based on very different principles.
These dampening units, known as continuous film dampeners, vary
considerably in their design and method of operation, but all eliminate the
outmoded, tedious and inaccurate aspects of the fabric-sleeved rollers. The
different types of dampening units most commonly used and an outline of their
mode of operation can be defined overall as follows
- continuous film dampening units on which the printing plate is dampened by
a dampening forme roller fed directly with a thin film of dampening water. In
this method of dampening, the emulsification of dampening water and ink
essential for offset printing is effected by the printing plate and the
dampening
forme roller, which is inked by the printing plate, since the oleophilic
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2.15184
properties of the rubber of which this roller is made are superior to its
hydrophilic properties. These units are generally provided with a
complementary function operating in parallel, enabling them to convey an
additional supply of dampening water to the first dampening forme roller,
thereby augmenting and accelerating the formation of the water-ink emulsion
and providing the close interconnection between the inking and dampening
processes. This complementary function also provides the possibility of
cleaning the dampening unit by the use of the cleaning device of the inking
unit.
In this type of dampening unit, the continuous film of dampening water is
generally formed instantly by the action of two rollers rotating against each
other under light pressure, at distinctly different relative speeds, fed with
water
taken up from the reservoir trough and conveyed for rolling by the water-duct
roller. These two rollers, of which one is usually made of steel surtaced with
matt-finish chrome, and the other coated with a micro-porous rubber, are
driven jointly at speeds variable from that of the dampening roller of the
printing plate. Modification of the ratio between these two velocities has an
instant effect upon the thickness of the water film formed on the dampening
roller and makes possible a precise and uniform regulation of the quantity of
water delivered to the printing plate.
- in another type of dampening unit, the printing plate is directly dampened
and partially inked by means of a continuous film composed of a fine emulsion
of dampening water and ink, deposited on the printing plate by the dampening
forme roller. This micro-emulsion of water in ink is created directly and
continuously by rolling the two constituents between rollers coated
alternately
with soft and hard oleophilic materials (such as rubber and hard plastic of
the
polyamide type). The rollers are first inked and then dampened. The number
of dampening unit rollers can be limited according to the nature and hardness
of the rubbers used for the coatings and their contact pressure. A perfectly
uniform emulsion is created with a few revolutions of the press and is
sustained very evenly as printing proceeds by an evenly balanced supply of
ink from the inking unit via the printing plate and the dampening roller where
' an alternating movement of ink and water between the dampening unit and
the inking unit is established instantly and reaches perfect stability,
directly
PCTIEP94100542
WO 94119189
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2I~.~843
achieving integration of the dampening and inking operations. The quality of
the emulsion is improved by choosing additives for the dampening water
which make it possible to limit the proportion of water retained in the
emulsion,
but as the mechanical action executed during rolling is extremely efficient,
even a hard water (pH 30) without additives will permit printing of acceptable
quality.
Inking of these dampening units is most frequently performed with a spatula,
and cleaning is carried out with the use of the cleaning device of the inking
unit to which it is temporarily linked by means of the printing plate. This
procedure presents certain drawbacks, since the printing plate is partially
destroyed by the cleaning agents and after cleaning it is necessary to clean
the edges of the printing plate and of the plate cylinder which have been
loaded with liquefied ink by the cleaning agents. Another disadvantage of
these dampening units is that they do not possess a complementary system
for the occasional conveyance of a small additional quantity of water-ink
emulsion to the first inking forme roller, a function which is useful where
the
printing demands very intense loads and large areas of ink.
- other dampening units, less professional, convey the water directly to the
first
inking forme roller, but fail to take advantage of the barrier provided by the
printing plate to avoid the risk of excessive application of emulsion to the
whole inking unit, which engenders Joss of density and vigour in the
impression.
Every manufacturer has his own design of dampening unit, varying according
to the size of the equipment being manufactured.
These various basic principles for the dampening of the printing plate by
continuous film make it possible to reduce dampening to a minimum, thereby
improving the vigour and definition of the impression, while greatly reducing
the risk of accidental ink transfer between the sheets when they are stacked
in
the delivery pile.
Furthermore, these continuous direct acting units do not incorporate sleeved
rollers, which limits evaporation of the dampening water and so makes it
possible, for some kinds of work, to add isopropyl alcohol to the water to
lower
its surface tension and improve its film forming properties, thereby-reducing
to .
a minimum the thickness of the film applied to the plate.
PCTIEP94I00542
WO 94119189
- 21~.~843
The precision of function of these different units in operation, their rapid
response times, the high quality of the impression they produce and their ease
of use are all factors contributing to their wide distribution.
In consideration of this fact, some manufacturers of accessories for printing
presses have designed continuous film dampening units based on the same
operating principles as those supplied as original components during the
manufacture of presses. These units, which are completely autonomous,
possess all the functions required for dampening of the printing plate. Such a
unit is independent in operation, and is installed in place of the original,
conventional dampening unit. It possesses its own body, which incorporates
ail the mechanical components and control mechanisms. However, the
installation of these independent units is a long job demanding profound
modifications to the mechanism of the press and rendering the conventional
dampening unit unserviceable by the removal of its essential components.
These adaptations are a delicate operation, since it is difficult with an
added
unit to ensure, and to maintain in a reliable manner, perfect geometry and
alignment of the main components of these units relative to the plate cylinder
and the inking forme roller of the press, components with which they
nevertheless have to operate in perfect and precise harmony if the modified
press is to function properly. Furthermore, the fact that the controls of the
replacement unit are not fully integrated with the controls for automatic
operation of the printing cycle, which are normally operated with a single
lever, obliges the printer to change his working habits.
The invention described here aims to remedy the weaknesses of conventional
dampening units and provide an improved general alternative solution for
their replacement. It is characterized by the conversion of a conventional
dampening unit into a continuous film dampening unit, specially designed
from the starting point of the main components and mechanisms of the
conventional unit which it utilises for its construction, installation and
operation. This procedure offers a number of important and clear advantages
which may be summarized overall as follows
- For its construction, installation and operation, the continuous unit
benefits
from the perfect geometry of the press of which, as far as its principal
215 1843
mechanisms are concerned, it becomes an integral part in the same way as the
original dampening unit.
- The main basic components of the continuous dampening unit are fitted and
driven in place of those of the original unit and may utilise the same or
different
functions according to the type and design of press. Positioning the basic
components of the continuous unit by means of the same mountings and drive
mechanisms of the press ensures perfect geometry and alignment with respect
to those parts of the press with which they have to work in unison. Assurance
of the reliability of the continuous unit is also provided by use of the drive
1 o mechanisms of the press to drive the main components of the resulting
continuous unit, due to their strength and quality of manufacture.
- The massive, stable body of the press locates and receives, by means of
attachment created from active components of the conventional unit, all the
supplementary components required for the functioning of the converted unit.
- The printer retains his working habits unchanged, with his usual control
lever.
- The cost of these units, thanks to the incorporation of a good number of the
components of the conventional dampening unit, is incomparably lower than
that of a supplementary, independent unit.
- The conversion of the conventional dampening unit into a continuous
2 o dampening unit is simple and quick, without any machining or drilling of
holes
in the press, a very advantageous aspect for the printer, since he knows that,
in
case of a breakdown, he can himself restore his original dampening unit in a
very short time while waiting for a repair to be carried out.
In its larger aspect the invention provides an offset printing press
comprising a
frame, a printing plate cylinder rotatably mounted to the frame, a water
supply
mounted to the frame, and a water take-up roller rotatably mounted to the
frame
and in communication with the water supply. A dampening distributor roller is
rotatably mounted to the frame, and a dampening forme roller is rotatably
mounted to the frame in rolling contact with and positioned between the
3 o dampening distributor roller and the printing plate cylinder. An ink
distributor
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2151843
roller is rotatably mounted to the frame, and an ink forme roller is rotatably
mounted to the frame in rolling contact with and positioned between the ink
distributor roller and the printing plate cylinder. A dampening unit is
detachably
mounted to the frame and includes a regulator roller, a transfer roller and a
liaison roller, each of which are rotatably mounted on the dampening unit. The
regulator roller is in selective rolling contact with and positioned between
the
water take-up roller and the transfer roller. The transfer roller is in
rolling
contact with and positioned between the regulator roller and the dampening
distributor roller and the transfer roller is in rolling contact with and
positioned
1 o between the liaison roller and the regulator roller, and the liaison
roller is
positioned between the ink forme roller and the transfer roller and is in
rolling
contact with the transfer roller and in selective rolling contact with the ink
forme
roller.
By another aspect, the invention provides a dampening add-on unit for
mounting in an offset printing press, the offset printing press having a
printing
plate cylinder rotatably mounted to a main frame and having an ink roller
mechanism and a dampening roller mechanism in rolling contact with the
printing plate cylinder. A water take-up roller mechanism cooperates with the
dampening roller mechanism. The dampening add-on unit comprises:
2 o a unit frame detachably mountable to the main frame of the printing press,
and
a regulator roller, a transfer roller and a liaison roller, each of which are
rotatably mounted on the unit frame in series in a side-by-side relationship
so
that the transfer roller is in rolling contact with and positioned between the
liaison roller and the regulator roller. Upon mounting the unit frame to the
main
frame in the offset printing press, the dampening add-on unit is disposed and
arranged within the offset printing press so that: the liaison roller of the
dampening add-on unit is positioned between the ink roller mechanism of the
offset printing press and the transfer roller of the dampening add-on unit so
that
the liaison roller of the dampening add-on unit is selectively in rolling
contact
3 o with the ink roller mechanism of the offset printing press; the regulator
roller of
- 6a -
A
2151843
the dampening add-on unit is positioned between the water take-up roller of
the
offset printing press and the transfer roller of the dampening add-on unit so
that
the regulator roller of the dampening add-on unit is selectively in rolling
contact
with the water take-up roller of the offset printing press; and the transfer
roller
of the dampening add-on unit is positioned adjacent and in selective rolling
contact with the dampening roller mechanism of the offset printing press.
By a further aspect the invention provides a procedure for converting an
offset
printing press dampening unit from alternating feed to a continuous feed
system. The method includes providing an offset printing press including a
1 o frame, a printing plate cylinder rotatably mounted to the frame, a water
supply
mounted to the frame, a water take-up roller rotatably mounted to the frame
and
in communication with the water supply, a dampening distributor roller
rotatably
mounted to the frame and spaced from the water take-up roller, and a
dampening forme roller rotatably mounted to the frame in rolling contact with
and positioned between the dampening distributor roller and the printing plate
cylinder. An ink distributor roller is rotatably mounted to the frame, and an
ink
forme roller is rotatably mounted to the frame in rolling contact with and
positioned between the ink distributor roller and the plate cylinder, the ink
forme roller being spaced from the dampening distributor roller and the
2 o dampening forma roller. A water duct roller is rotatably mounted on a
pivoting
arm pivotally connected to the frame, the water duct roller capable of being
in a
first position in rolling contact with the water take-up roller and in a
second
position in rolling contact with the dampening distributor roller. In this
procedure the water duct roller and associated pivoting arm from the frame are
removed, and a dampening module is detachably mounted to the frame. The
dampening module includes a regulator roller, a transfer roller and a liaison
roller, each of which are rotatably mounted on the dampening module. The
dampening module is configured and arranged so that, when mounted on the
frame, the regulator roller is in selective rolling contact with and
positioned
3 0 between the water take-up roller and the transfer roller, the transfer
roller is in
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AY
2151843
rolling contact with and positioned between the regulator roller and the
dampening distributor roller and the transfer roller is in rolling contact
with and
positioned between the liaison roller and the regulator roller, and the
liaison
roller is positioned between the ink forme roller and the transfer roller and
is in
rolling contact with the transfer roller and is in selective rolling contact
with the
ink forme roller.
To assist in an understanding of this invention and its relationship to prior
practices and apparatus, as well as to provide detailed description of
exemplary embodiments of apparatus according to the invention, reference will
1 o be made to the accompanying drawings, in which:
Figures 1, 2 and 3 diagrammatically illustrate a conventional dampening unit
on
an offset printing press;
Figures 4, 5 and 6 illustrate an embodiment of a printing press and a
dampening unit according to this invention;
Figures 7(A) and (B) show a simplified dampening unit similar to the previous;
Figure 8 illustrates an alternative embodiment of a dampening unit including
features of the invention; and
Figure 9 shows modified apparatus similar to that seen in Figure 8.
By way of illustration, there follows, not an exhaustive list, but a
description of
2 o four examples of ways of converting original dampening units using sleeved
rollers into continuous film dampening units. Two of these examples concern a
method of dampening in which the printing plate is dampened with a water-ink
emulsion, and the other two methods in which the plate is dampened by
continuous film. These different examples bring improvement in use or in cost
of installation by comparison with the techniques usually applied. In order
that
the existing means employed to realize the invention in its different forms
may
be fully understood, the mode of operation of a conventional dampening unit
before conversion is first described with the aid
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2~5~8~3
of three diagrams. Figures 1, 2 and 3 represent a conventional dampening
unit on an offset printing press. Figure 1 shows a diagrammatic representation
of the roller used for direct dampening of the printing plate together with
the
water feed system. The reservoir 1 has no air inlet, so feed to the trough 2
occurs as a function of consumption by the press, the water level never rising
above the bottom of the tap 3 which thus acts as a regulator of the level of
the
dampening solution. The water take-up roller 4 is partially immersed in the
dampening water contained in the trough 2 and the general mechanism of the
press periodically rotates it by a varying amount, according to the quantity
of
water required for correct dampening of the printing plate. The water duct
roller 5, supported at each end on the bell cranks 6 tilting on the pivots 7,
oscillates with a cyclical movement imparted by the mechanism of the press.
At each printing cycle, this movement brings it into contact alternately with
the
water take-up roller 4, where it picks up the water required for the
impression,
then with the dampening distributor roller 8 moving with an axial motion,
where it deposits the water. The dampening forme roller 9 rotates in
permanent contact with the dampening distributor roller 8 to take up its
moisture, part of which it then passes on to the other dampening forme roller
10 by way of the degreasing roller 11. The water. duct roller 5 and the two
dampening forme rollers 9 and 10 are covered with a sleeve of porous
molleton which acts as a water reserve supplied by the dampening distributor
roller 8. The printing plate fixed on to the plate cylinder 12 is thus
dampened
as soon as it is brought into contact with the dampening forme rollers 9 and
10
on the decision of the press operator, the levers 13 and 14 pivoting about the
axles 15 and 16. After this action has been taken to dampen the printing
plate,
the inking forme rollers 17, 18, 19 and 20, in contact with the ink
distributor
rollers 21 and 22, can begin to ink the printing plate on the plate cylinder
12 to
enable printing to start.
Figure 2 and its profile view Figure 3 show in greater detail the mechanical
means employed to hold in place, adjust and move the rollers constituting the
dampening unit of a traditional press of one of the most widely used types.
The trough 2 Figure 2 is suspended from the cross member 23 which lends
rigidity to the side panels 25 of the body of the press by means of the hooks
24
and two wing nuts which are omitted from the drawing in the interests of
,"~, WO 94119189 PCTIEP94100542
X151843
clarity. The trough 2 can be removed very quickly by undoing these two nuts.
The water take-up roller 4 is rotated by the half-shaft 26 Figure 3 carrying
at
one end a device for inducing rotation actuated by the general mechanism of
the press. At the other end, the half-shaft 26 carries a half clutch 27 and a
bore
into which is introduced the axle of the water take-up roller 4. The fatter
carries
the second clutch half 28, engagement of which in the half clutch 27 induces
rotation of the assembly. At the other end, the axle of the water take-up
roller 4
is engaged in a sliding half-shaft 29 kept pressed against the circlip 30 by
the
return spring 31. The lug 32 keeps the return spring 31 under constant
pressure thus ensuring that the water take-up roller 4 is kept in place. The
collar 33, equipped with a needle roller free-wheel 34 allows for the
possibility
of manual rotation of the water take-up roller 4 by means of the lever 35.
This
mechanical arrangement makes possible very rapid dismantling of the water
take-up roller 4 by pressure on the sliding half-shaft 29 which compresses the
return spring 31 thus permitting disengagement of the axle of the water~take-
up roller 4. The water duct roller 5 with its molleton sleeve 5A carries at
each
end a ball bearing 36 located between two fixed pins 37 and 38 Figure 2 and
one sliding pin 39 arranged in a triangle in the bell cranks 6. Operation of
the
buttons 40 Figure 3 frees the ball bearings 36 and so permits removal of the
water duct roller 5. The same mechanism is used to retain the dampening
forme rollers 9 and 10 Figure 2 supported by the levers 14 and 13, the latter
being associated with the adjusting counter-lever 13A in which are engaged
the fixed pins 37 and 38 and the sliding pin 39. These mechanisms permit
rapid and easy removal of the water duct roller 5 and the dampening forme
rollers 9 and 10. It will have been necessary first to remove the degreasing
roller 11. This is normally held in place against the dampening forme rollers
9
and 10 by the action, at each end, of the pressure springs 41 supported by the
journals 42. These pivot in the levers 43 which are tilted manually on the
stub
axles 44 by means of the handles 45, them movement being limited by the
stops 46 and 47. The slide-bars 48 guide the pressure springs 41 and are
mounted on the fixed axle 11A of the degreasing roller 11 by means of the
slide bar heads 49 which have a centring vee at their tip. The degreasing
roller 11 rotates about the fixed axle 11A on ball bearings. Tilting the
levers~43
by means of the handles 45 thus quickly and easily disengages the
~ WO 94/19189 PCTBP94I00542
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215183
dampening forme rollers 9 and 10 to permit their removal. This operation is
performed daily and generally several times a day at each change of printing
ink colour.
By way of example, there follows, with references to the attached drawings, a
description, which is not an exhaustive list, of the means employed to convert
an alternating feed dampening unit to continuous feed.
The first example described with reference to attached drawings Figures 5
and 6 concerns a dampening unit having the following characteristics and
functions
- continuous dampening of the printing plate with a water-ink emulsion,
- automatic pre-inking of the dampening unit by the press,
- automatic washing of the dampening unit by means of the washing system of
the press,
- optional, supplementary application of emulsion to the first inking forme
roller, a useful function where the print includes very large inked areas.
This first example includes a characteristic supplementary to those of the
most
frequently used units that provide continuous dampening of the printing plate
by water-ink emulsion : this provides for the possibility of equipping the
presses, according to their type and their printing speed, either with a water
take-up roller and water duct roller made of plastic in the usual way or,
according to the allowable cost for conversion of these presses, with water
take-up rollers and water duct rollers made of almost pure copper or a similar
material possessing oleophilic and hydrophilic properties which engender a
much finer water-ink emulsion, containing a lower proportion of water and
making it possible to prevent excess ink from accumulating on the water take-
up roller 4. Furthermore, heat loss from copper being very much more rapid
than from plastics, this allows the emulsion and the ink on the printing plate
and forme rollers to be maintained in a less fluid state, greatly improving
printing quality.
In addition, cleaning of copper components is much faster and greatly
superior to that of plastic components and for offset presses printing
continuously at high speeds, such as rotary or similar, copper is the
unhesitating choice.
~ WO 94119189 PCTJEP94/OOS42
-1°- 2.~518~3
The second example, Figure 7, relates to a dampening unit operating on the
same principle as the first but greatly simplified, so that
- it requires manual pre-inking by spatula
- it requires manual cleaning
- there is no facility for supplementary inking of the first inking forme
roller.
The third example, Figure 8, relates to a dampening unit comprising all the
functions of the first example from which it derives, but is characterized by
the
fact that the printing plate is not dampened with a water-ink emulsion, but
with
a microfilm of water. This variation is obtained chiefly by the use of
different
coating materials, possessing either oleophilic properties, such as copper,
polyamide (Rilsan) or others for the first and second examples, or hydrophilic
properties in the third and fourth examples, such as hard chrome or
microporous ceramic, or rubber rollers of types already known, which
themselves possess properties which may be oleophiiic, hydrophilic or mixed.
In the third example and according to this form of the invention, bearing in
mind that at a given speed hydrophilic or mixed materials convey much more
water to the printing plate than is conveyed by emulsion, where an equilibrium
between water and ink establishes itself naturally, the quantity of water
conveyed to the unit is controlled and regulated by using the original
variable
speed drive mechanism of the water take-up roller and instantly creating a
small reserve of water by the assembly of rubber transfer rollers which have
hydrophilic properties and a microporous surface texture obtained by grinding
with coarse-grained, semi hard grinding wheels, so that the printing plate is
supplied with a continuous microfilm.
The fourth example Figure 9 relates to a device similar to the third, but
obtains
the quantity of water by varying the relative rotation speeds of the water
take-
up roller 4C and the drying roller 4D with respect to the transfer roller 66A
turning at the speed of the press. This procedure permits centralized
adjustment of the controls of the motor or motors driving these two rollers at
variable speeds and is of particular interest in the case of multi-colour
presses
comprising successive printing units in line.
Figure 4 shows the printing press ready to receive its removable module
Figure 5 to complement the dampening unit. The dampening forme roller.9
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Figure 3 covered with a porous molleton sleeve, the chrome dampening
distributor roller 8 and the water take-up roller 4 have been replaced
in the first example
- by a rubber dampening forme roller 9A of the same diameter, possessing
oleophiiic and hydrophilic properties, each end of which carries a band 9B
composed of a much harder rubber (hardness about twenty-five Shore for the
roller and sixty-six Shore for the bands) designed to press against and work
together with the bands of the plate cylinder 12 Figure 1.
- by a dampening distributor roller 8A of the same diameter as the original
one, having a surface coating of hard copper of five to six tenths of a
millimetre
thickness, bearing at one end a gear wheel 8B designed to transmit its motion
to the assembly of other rollers of the converted dampening unit.
- by a water take-up roller 4A, copper clad, also of the same diameter,
mounted free to rotate on its axle by means of the bearings 4B. Its axle is
itself
driven by the same cyclical mechanism as the original water take-up roller 4
Figure 3, by the mechanism of the press without driving the water take-up
roller 4A. Whatever the design and whatever the mechanical configuration
adopted for the application of the invention, the dampening distributor roller
8A Figure 4 and the dampening forme roller 9A retain their original function,
so as to guarantee pertect geometry with respect to .the plate cylinder 12
Figure 3 and to conserve also the cyclical automatic printing functions
regarding the making and breaking of contact between the printing plate and
the dampening forme roller 9A.
In examples one, three and four, the rollers are driven positively by gears to
permit automatic washing of the dampening unit and avoid the necessity for
the operator to take precautions with regard to the distribution of the
cleaning
solvents, as too much greasy solvent can lead to slippage between the rollers
of the dampening unit and render the cleaning operation difficult. However,
these gears do not contribute to the functioning of the dampening unit.
Figures
5 and 6 show sectional and top views of an example of a dampening unit
which gives very good results and is very practical to use for the operator of
the press.
The removable module 55 Figure 5 can be installed in and removed from the
press effortlessly and in a few seconds, giving easy access to the other
WO 94119189 PCTlEP94/00542
-12-
2~~18~3
elements of the press. It comprises all the supplementary mechanisms of the
dampening unit. Its location and detachable fixing to the press are effected
occupying the position of the original water duct roller 5 Figure 2 and using
the control shaft of the duct roller 56 for support. To do this, the duct
roller
control must be locked, which is done by moving the cam 58 Figure 5 by
means of the lever 59 to push back the return lever 57. Adjustment can be
carried out by means of the nuts 60 Figure 2.
The removable module 55 Figure 5 is composed of two side plates 61 cross-
braced and located by two centring pieces 62 which occupy the positions of
the bearings of the original water duct roller 5 Figure 2, captive between the
fixed pins 37 and 38 and the sliding pins 39. The rubber-covered transfer
roller 63 Figure 5 is mounted turning on a fixed axle 64 which acts as a cross-
brace, as does the cross-member 65 between the two side plates 61.
Adjustment of the touch of the hard copper-covered dampening distributor
roller 8A against the transfer roller 63 is performed by the nuts 60 Figure 2
when the touch of the different rollers is being adjusted. A regulator roller
66
effects the liaison between the water take-up roller 4A and the transfer
roller
63. It is mounted fuming on a fixed shaft 67, which is itself mounted on two
oscillating supports 68 and subjected to pressure by means of the screws 69
maintaining it in constant contact with the transfer roller 63. Its
application to
the water take-up roller 4A is effected by the action of the eccentric 70
moved
by the lever 71 acting on the oscillating support 68 through the adjustment
screw 72. Its contact with the water take-up roller 4A is broken manually by
rotating the eccentric 70, releasing the oscillating supports 68 which are
withdrawn by the springs 73. The rotation of the transfer and regulator
rollers
63 Figure 6 and 66 is driven by a gear train originating at the dampening
distributor roller 8A. The first gear wheel 8B is smaller in diameter than the
exterior of the dampening distributor roller 8A so as to avoid bottoming on
the
bands 9B Figure 4 of the dampening forme roller 9A situated just opposite. To
compensate for the difference in speed resulting from this inequality, a set
of
pinions 74 and 75 Figure 6, keyed on to the same rotating shaft 76, re-
establishes the proper speed ratio. Hence an intermediate pinion 77, mounted
rotating on a fixed shaft 78, transmits the rotation at the right speed and in
the
right direction to the transfer roller 63 by means of the pinion 79 fixed to
the ~'
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-'3- ~I~:I843
latter. The regulator roller 66 is similarly driven through the pinion 81
fixed to it
and the pinion 80 fixed to the transfer roller 63.
Finally, a connecting roller 82 brings the transfer roller 63 into contact
with the
inking forme roller 20. It is mounted turning on a fixed shaft 83. This
maintains
it under permanent pressure against the inking forme roller 20 by the action
of
two spring thrusters 84. Two more spring thrusters 85 Figure 5 unstick it
vertically upwards, thereby keeping it separate from the transfer roller 63.
The
two are brought into contact by manual action on an eccentric 86 Figure 6,
operated through the two levers 87 acting on two rockers 88. The screws 89
Figure 5 regulate the pressure. In order to permit the connecting roller 82 to
follow the movement of the inking forme roller 20 when it pivots during the
operation of making contact with the printing plate, the pivots 90 of the
rocker
88 are mounted on two levers 91 turning on the pivots 92 and supported on
the locating pins 93 of the inking forme roller 20. The connecting roller 82
effects either the pre-inking or the washing of the dampening unit by way of
the inking unit, or can obtain a "frilly" printing effect by conveying
additional
water to the first inking forme roller to intensify the water-ink emulsion.
The
emulsion and its regulation are obtained between the copper-covered water
take-up roller 4A and the rubber-covered regulator roller 66.
Views A and B of Figure 7 represent, in a simplified form of the invention, an
example of a water-ink emulsion continuous film dampening unit of very low
cost which does not offer al! the functional advantages of the preceding
example, but nevertheless gives vastly better results than those obtained with
the original unit..
In this configuration, the original dampening distributor roller 8 Figure 1 is
replaced by
the dampening distributor roller 8A Figure 7 Vew A, which is mechanically
identical but copper-covered. The rubber-covered water take-up roller 94
Figure 7 View A is driven by friction through the dampening distributor roller
8A and turns in the bearings 94A equipping the trough 95, which is supported
by two side members 96 fixed to the cross-member 97 by means of the
removable clamping tugs 98. The emulsion is formed between the rubber-
covered water take-up roller 94 and the dampening distributor roller 8A which
have previously been inked. The dampening distributor roller 8A performs the
' PCT/EP94100542
WO 94119189
-14- ~~~1843
functions of a regulator roller and of transferring the emulsion to the
dampening forme roller 9A. The axial displacement movement of the
dampening distributor roller 8A as it turns, known as "reciprocation", ensures
perfect distribution of the emulsion on the dampening forme roller 9A. Should
the dampening forme roller 9A be laterally fixed, the unit would be unable to
work, as there would be rapid accumulation due to excess water. This excess
originates either from the end surfaces of the rubber-covered water take-up
roller 94, if this is shorter than the dampening distributor roller 8A, length
of
reciprocation included, or if the dampening forme roller 9A is the same length
7 0 as the dampening distributor roller 8A or longer, the latter, in its axial
movement, loses contact with part of the rubber-covered water take-up roller
94 on which the water, no longer regulated, spreads out under the action of
this movement between the dampening distributor roller 8A and the
dampening forme roller 9A. One of the characteristics of the invention is to
make the rubber-covered water take-up roller 94 follow the dampening
distributor roller 8A in its axial movement to enable the unit to operate.
This
axial displacement of the rubber-covered water take-up roller 94 is achieved
by equipping the stub axle 50 Figure 3 of the dampening distributor roller 8A
Figure 7 dew 8 with a steel disc 99 opposite which the shaft 100 of the
_ 20 rubber-covered water take-up roller 94 carries a polyamide disc 101 with
a
central groove in which the steel disc 99 engages. The bearings 94A are fixed
on to the side members 96 and each contain a ball race 94B accommodating
the rotational and axial movement of the shaft 100 fixed in the rubber-covered
water take-up roller 94 which corresponds in length to the dampening
distributor roller 8A.
The third example shown in illustration of the possibilities of the invention
employs the same mechanisms as those used in the first example but with the
variations summarized below.
The dampening distributor roller SB Figure 8 and the water take-up roller 4C
are not copper covered but hard chrome plated or covered with a high-
polished micro-porous ceramic. The drying roller 4D and transfer rollers 66A
and 63A are covered with rubber of known hydrophilic properties. The
dampening forme roller 9A and liaison roller 82 remain identical to those in ,
the first example. One of the characteristics of the invention, in certain
forms, 'is
r~ WO 94/19189 PCTJEP94100542
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the use, for the purpose of refining regulation of the quantity of water taken
up
from the trough, of the original mechanism of the press acting as an
alternative
means of taking up a certain quantity of water by means of the water take-up
roller 4 Figure 3. This mechanism employs a half clutch 28 to drive the shaft
of
the water take-up roller 4 in periodic rotation variable in amplitude and
adjustable with precision. In this configuration, the original water take-up
roller
4 is replaced with a regulating roller 4D Figure 8 equipped with a similar
half
clutch so as to be subjected to the same method of drive transmitted by
friction
through the water take-up roller 4C. The action of the regulating roller 4D
makes it possible to take up a film of water of even thickness by means of the
transfer roller 66A driven at the speed of the press, a function not performed
by the original unit, which does not regulate the quantity of water taken up.
These two slightly porous rollers store a small quantity of water in their
pores
and at the tangent points between them and the dampening distributor roller
8B where the continuous film is formed. This arrangement differs from the
first
example in that the touch between the regulating roller 48 and the transfer
roNer 66A is extremely light, of the order of one millimetre, to enable slip
to
occur at the tangent point of the latter two rollers turning at different
relative
speeds.
The fourth example, like the third, operates by dampening the printing plate
by mean of a continuous film of water and includes remote controlled water
film regulation by means of a motor 102 Figure 9 driving the water take-up
roller 4C and regulating roller 4D at different and variable speeds with
respect
to the other rollers which turn at the speed of the press. Two side elements
103 support the motor assembly and are fixed to the cross-member 97 of the
press by means of.the clamping lugs 98. This assembly is supported on the
body of the press by the base plate 104 equipped with a height adjuster in the
form of the threaded rod 105. Adjustment of the height of the motor assembly
determines the pressure exerted by the water take-up roller 4C against the
regulator roller 4D. The synchronous belt 106 transmits the movement to the
gear train driving the different rollers.
These few examples, which do not constitute an exhaustive list, make it
possible to understand the object of the invention and the advahtages which
these conversions offer. The printer is enabled, at modest expense, to improve
' ;~.. WO 94/19189 PCT/EP94l00542
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~1 X1843
the quality of his printing very considerably while at the same time gaining
ease of use and a substantial increase in productivity. These improvements
open a wide field of possibilities for this procedure.
Any of these conversions can be incorporated directly during manufacture of
the press at even lower cost.
