BACKGROUND OF INVENTION
[0001] It is well known in the printing industry that it is extremely difficult to obtain
high quality when printing certain forms, such as one-half page, combinations of screens
and solids, diagonals, and the like. These forms are difficult to print because of
the problems associated with "ghosting", ink starvation and accumulation, linting,
or ink slinging. Some of these problems have been partially solved by the inovative
inventions disclosed in Pat. No. 4,208,963, Pat. No. 4,233,898, and Pat. No. 4,237,785.
[0002] In U. S. Patent No. 3,926,114 to Matuschke and U. S. Patent No. 3,587,463 to Granger,
it has been suggested that a scraping off device be positioned to engage an inking
roller in a letterpress to remove the negative ink relief to thus avoid the accumulation
of ink on rollers in an ink supply mechanism. In letterpress printing, ink is applied
to raised image areas on a printing cylinder while recessed non-image areas remain
free of ink. However, in lithographic printing, ink and dampening fluid are applied
to a planographic printing plate. U. S. Patent No. 3,926,114 to Matuschke discloses
a device in which ink and dampening fluid scraped off of a roller are passed into
a separator so that the characteristics of the ink are not altered by the add mixture
of dampening fluid. Thus, pure ink was metered to the form roller by the inking system
to prevent "greying" or the accumulation of excess dampening fluid within the ink
supply as the ink was transferred to the inking roller.
[0003] U. S. Patent No. 4,211,167 to Corse discloses a rod pressed under strong pressure against
a soft surface carrying a layer of ink and dampening fluid, the rod forming a barrier
only against the dampening fluid while allowing all the residual film of ink remaining
on the inking roller to pass and return to - a mass of ink in a reservoir.
[0004] The present invention provides a solution to problems encountered in separating ink
and dampening fluid by permitting the emulsified ink and dampening fluid to be used
again. We have discovered that if unused ink and dampening fluid are thoroughly mixed
with fresh ink to form a substantially homogeneous mixture, ink and dampening fluid
removed from.a lithographic printing press equipped with an inker and a dampener can
be removed from a form roller to prevent accumulation and remetered for application
to the form roller provided the emulsified ink and dampening fluid are not kept in
a confined area long enough for the ink and dampening fluid to separate.
[0005] Accordingly, it is an object of the present invention to provide an ink removal,
circulating and distributing system that meters a substantially homogeneous mixture
of ink and dampening fluid to a form roller for use in a lithographic printing system
wherein an improved distribution system maintains the homogeneous mixture sufficiently
agitated to prevent separation of the ink and dampening fluid.
[0006] Further, it is an object of the present invention to provide a substantially homogeneous
mixture of printing ink and dampening fluid for use in a printing system.
[0007] It is a further object of the invention to provide a circulating system which eliminates
heat build up in an ink reservoir.
[0008] A further object of the invention is to maintain a uniform viscosity consistency
of an ink emulsion throughout a printing run.
[0009] A still further object of the invention is to provide apparatus to remove ink and
dampening fluid from a form roller and to reapply the ink and dampening fluid to the
form roller, in combination with a dampener having a hydrophilic roller adapted to
deliver a metered film of dampening fluid to the form roller and to remove excess
dampening fluid from the form roller.
SUMMARY OF THE INVENTION
[0010] in accordance with the invention, a printing system includes a printing plate, a
single form roller engaging the printing plate and apparatus to apply ink and dampening
fluid to the single form roller. The improvement comprises apparatus to remove ink
and dampening fluid from the single form roller after the single form roller engages
the printing plate. The ink and dampening fluid are then mixed with fresh ink to form
a substantially homogeneous mixture and this substantially homogeneous mixture is
then applied to the single inking form roller. A hydrophilic roller applies dampening
fluid to the single form roller and removes excess dampening fluid from the single
form roller.
[0011] Further, in accordance with the invention, an ink removal, circulating and distributing
system comprises means for directing excess ink and water, which was left on a form
roller after application to a lithographic printing plate, to a reservoir of fresh
ink, mixing the fresh ink and the excess and returning the resultant conditioned,
homogeneous mixture of dampening fluid and ink to a place of origin, such that the
now homogeneous conditioned mixture is supplied in such an abundant quantity that
it is not kept in a confined area long enough for water to separate therefrom to cause
non-uniform ink pick-up or stripping of ink from printing rollers.
[0012] It has been observed that when an abundant quantity of an emulsion of water in ink
remains in one given area for a period of time, either between two rollers or between
a roller and a blade, that the emulsion will be squeezed and water separated therefrom
to cause a resultant non-uniform pick-up of ink or ink stripping from the roller or
rollers. It is therefore advantageous to limit the time that the emulsion stays in
one given pressure area.
[0013] We have found that when supplying the pressure area with an excess of the emulsion,
flow must be maintained such that a given quantity of emulsified ink stays in a given
pressure area only a limited amount of time sufficient to allow the emulsion to pass
along the pressure area, but not allow time for water to be squeezed therefrom and
remain in the given pressure area to cause problems.
[0014] We have therefore been able to print continuously with a controlled emulsion of dampening
fluid and ink wherein before, the emulsion supplied to the pressure area would separate
into water and ink, and the water would cause non-uniform ink pick-up and stripping
of ink rollers.
[0015] Other objects and advantages of the invention will become more apparent upon reading
the following detailed description and upon references to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Drawings of three embodiments of the invention are annexed hereto wherein like reference
characters are used throughout to designate like parts, in which:
FIG. 1 is a fragmentary diagrammatic perspective view of a first embodiment of the
invention;
FIG. 2 is a diagrammatic illustration of an inking system constructed according to
the present invention as used with a newspaper printing system with the various films
of ink and dampening fluid being illustrated;
FIG. 3 is a diagrammatic illustration of an ink removal, circulating and distributing
system constructed according to the present invention;
FIG. 4 is a diagrammatic illustration of a second embodiment of an ink removal, circulating
and distributing system constructed according to the present invention; and
FIG. 5 is a diagrammatic illustration preferred embodiment of a multi-unit newspaper
printing system incorporating the ink removal, circulating and distributing system
of FIG. 4.
DESCRIPTION OF THE INVENTION
[0017] A printing system 1 is illustrated in FIGS. 1 and 2 which includes an inking system
2, a scraping-off means 26, a reservoir 14, a pump 32 and motor 34, by-pass line 38,
a distributor line 20 and nip N' between two adjacent rollers 12 and 13 in pressure
indented relation and a suitable dampener 200.
[0018] Ink is supplied to nip N' via ink distributor line 20 to the mid-point between ends
of rollers 12 and 13 in an abundant quantity such that the excess flows towards the
roller ends and cascades therefrom to be collected and supplied to reservoir 14 by
gravity feed. Blended in reservoir 14 with ink, the mixture or emulsion of ink and
dampening fluid removed from form roller 90 by roller 94 and scraping-off means 26
is pumped back to distributor line 20 to complete the circuit. By-pass 38 is provided
to enable pump 32 to run at a high rate of speed to thoroughly mix and circulate the
emulsion further. Pump 32 is preferably a constant displacement auger-type screw pump
driven by a variable speed air motor 34. Pump 32 and by-pass 38 provide adequate mixing
through circulation to form and maintain a homogeneous mixture of the ink and dampening
fluid.
[0019] Water and ink excess 128 left on the form roller 90 of the inker 2, after printing,
is applied to roller-94 and wiped off by scraping off means 26.
[0020] This non-uniform mix of water and ink is then preferably moved to reservoir 14 and
through pump 32 where it is thoroughly mixed with fresh new ink and/or previously
conditioned ink before returning to distributor tube 20. The dampener 200 is of the
general form roll contact-type disclosed in the U.S. Pat. No. 3,168,037, entitled
"Means For Dampening Lithographic Offset Printing Plates" which issued February 2,
1965 to Harold P. Dahlgren. The disclosure of U.S. Pat. No. 3,168,037 is incorporated
herein by reference in its entirety for all purposes.
[0021] The inker generally comprises a form roller 90, ink idler roller 10, ink transfer
roller 12, ink metering roller 13, and ink pan 14. Form roller 90, ink idler roller
10 and ink transfer roller 12 are generally supported between side frames (not shown)
as disclosed in PCT International Application No. 79/00948 filed June 3, 1980, entitled
"Inker For Newspaper Press", the disclosure of which is incorporated herein by reference
in its entirety for all purposes.
[0022] Suitable means are provided, as hereinbefore described, for delivering an abundant
supply of ink to the ink metering nip N' between adjacent surfaces of ink metering
roller 13 and ink transfer roller 12. In the particular embodiment of the invention
illustrated in FIG. 1, a distribution tube 20 discharges a substantially homogeneous
printing liquid 22 at the junction between rollers 12 and 13 with the liquid being
metered at ink metering nip and carried by the surface of roller 12 to thereby provide
ink at ink transfer nip N. A sufficient flow of liquid 22 is provided at the junction
of rollers 12 and 13 to maintain a flow of excess liquid over the ends of rollers
12 and 13 into ink pan 14, as will be hereinafter more fully explained.
[0023] Idler roller 10 and metering roller 13 are preferably hard and have an exterior surface
'which may be smooth or textured and which are ink receptive or oleophillic, such
as copper or plastic. The surface of ink idler roller 10 and ink metering roller 13
may be either hard or resilient, depending upon the characteristics of the surface
of form roller 90.
[0024] If the form roller 90 has a resilient surface, then the surfaces of the idler roller
10 and metering roller 13 are preferably hard.
[0025] Transfer roller 12 preferably comprises a hollow tubular sleeve 12a with a resillient
cover 12c secured about the outer surface of the sleeve. This cover material of ink
transfer roller 12 is selected so as to be oleophillic and the surface may be textured.
[0026] It should be readily apparent that if desired, the material of idler roller 10, ink
transfer roller 12 and ink metering roller 13 may be alternately hard and soft.
[0027] Ink idler roller 10 is preferably positioned in pressure indented relationship with
form roller 90, which has a metal tubular core 91 as described in U.S. Pat. No. 4,233,898.
[0028] Form roller 90 has a smooth outer cover 96 which may be non-absorbent or absorbent,
hard or soft, depending upon the nature of construction of printing plate 112.
[0029] In one embodiment, form roller 90 has a smooth outer cover 96 which may have a resillient
non-absorbent surface. Another embodiment of form roller 90 includes a resillient
surface and has a molleton type of cover which absorbs the ink and will reject dampening
fluid. However, if plate 112 has raised - image areas and is constructed of resilient
material, form roller 90 could be provided with a hard surface of, for example, copper
or a hard thin plastic covering.
[0030] Ink roller 94, preferably a traversing oscillating idler roller with associated scraping
off-means 26, is adapted to remove excess ink from areas 128" from ink film 128 on
the surface of form roller 90 and transfer some of the ink to depleted areas 128
1 thereby creating a more uniform film of ink 130 on the surface of roller 90 moving
from nip 120 towards nip 106 to be later explained more fully.
[0031] A second ink roller 95, similar to roller 94, is positioned between plate cylinder
P and dampener 200 to smooth the ink film upon reversal of form roller 90 as will
be more hereinafter fully explained.
[0032] A material conditioning roller 86, preferably an oscillating idler roller, is rotatably
supported as disclosed in U.S. Pat. No. 4,233,898. Roller 86, 94 and 95 are mounted
in pressure indented relation with form roller 90 each having a surface of preferably
similar material to that of form roller 90 such that the surface has the same affinity
for ink as does the surface of form roller 90.
[0033] As the ink film 100 emerges from nip 106 between form roller 90 and idler roller
10, it may be slick and calendared. A slick film of ink is not particularly receptive
to dampening fluid since the surface tension of the molecules of ink may reject the
thin layer of dampening fluid to be applied by dampener 200. Material conditioning
roller 86 will receive a portion of the film 100 of ink thus splitting the film 100
of ink and producing a film 100' on roller 86 thus leaving film 100a with a matte
finish having microscopic cavities or indentations. The matte surface upon film 100a
will readily accept the thin film 204 of dampening fluid.
[0034] Rollers 86, 94 and 95 are preferably provided with drive means (not shown) to oscillate
the rollers in a longitudinal direction. Suitable oscillator drive means are well
known to persons skilled in the printing art and further description is not deemed
necessary. Rotation is provided through friction contact with adjacent surfaces.
[0035] Dampener 200 is diagrammatically illustrated in FIG. 2 and comprises a hydrophillic
transfer roller 212 and a resilient metering roller 213 mounted in a manner similar
to inker 2 as described in U.S. Pat. No. 3,168,037. Metering roller 213 meters dampening
fluid 214a from pan 214 onto transfer roller 212 through flooded nip Na. Water film
controlled by pressure between rollers 213 and 212 forms a thin layer of dampening
fluid 204 which is metered through dampening fluid transfer nip D onto the matte finish
of ink film 100a on the surface of form roller 90.
[0036] Dampener metering roller 213 is driven by a variable speed reversible motor as described
in U.S. Pat. No. 4,233,898.
[0037] For the purpose of graphically illustrating the function and results of the process
of the mechanism hereinbefore described, a diagrammatic view of idler roller 10, transfer
roller 12, metering roller - 13 and form roller 90 is shown in FIG. 2. Ink and water
films are exaggerated for clarity.
[0038] Metering roller 13 is rotatably mounted in pressure indented relation with transfer
roller 12 and transfer roller 12 is rotatably mounted in pressure indented relation
with idler roller 10. The pressure between adjacent roller surfaces is adjusted such
that the surface of metering roller 13 and idler roller 10 are actually impressed
into the surface of transfer roller 12.
[0039] At the point of tangency, or cusp area between rollers 12 and 13, an excess 22 of
ink is piled up. The greatness of the excess of ink extending longitu-
- dinally of rollers 12 and 13 is regulated by virtue of the fact that excess ink will
fall into pan 14 by gravity to virtually create a "waterfall" of ink at opposite ends
of the nip between adjacent surfaces of rollers 12 and 13, and by virtue of the amount
of flow of liquid 22 from discharge tube 20. The excess of ink 22 in the flooded nip
becomes the reservoir from which ink is drawn by transfer roller 12. As rollers 12
and 13 rotate in pressure indented relation, a layer of ink is metered between adjacent
surfaces of the two rollers separated by a thin lubricating layer of ink. Since transfer
roller 12 has a smooth, oleophillic surface thereon, a portion of the film adheres
to the surface of roller 12 to form a film 104, the remaining portion being rotated
on the surface of roller 13 back into the excess. A film of ink 104 is distributed
on the surface of transfer roller 12 by reason of the rotating, squeezing action between
rollers 12 and 13 at their tangent point at ink metering nip N'. The film of ink 104
rides on the surface of transfer roller 12 and comes in contact with ink film 116
on idler roller 10 at ink transfer nip N to form a film of printing ink 104a on idler
roller 10.
[0040] The film of ink 104a rides on the surface of idler roller 10 and comes in contact
with a uniform film 130 of ink on form roller 90 at the inking nip 106 between idler
roller 10 and form roller 90.
[0041] It is important to note that idler roller 10 may or may not be positively driven.
If positively driven, it may be driven at a fixed ratio slower than the surface speed
of the adjacent form roll 90. In any event, the surface of idler roller 10 is driven
in the same direction as the adjacent surface of form roller 90. Idler roller 10 serves
as an intermediate applicator roll between form roller 90 and transfer roller 12.
[0042] At nip 106 and N, it will be observed that idler roller 10 is impressed into the
resilient surface of form roller 90 and transfer roller 12 and that the film of ink
104 has an outer surface 108, which contacts ink film 116, and an inner surface 110
which adheres to the surface of transfer roller 12. The outer surface 108 of film
104 and the outer surface
117 of the film of ink 116 on idler roller 10 are urged together to create a hydraulic
connection between rollers 12 and 10 as they rotate in close relationship, but there
is no physical contact between the roller surfaces. It is an important fact to note
that the relatively thick film of ink 104 permits rollers 12 and 10 to be rotated
at different surface speeds. Preferably, the form roller 90, which is normally press
driven and rotated at the same surface speed as the printing plate 112 is rotated
at a greater surface speed than the surface speed of roller 12. By regulating the
differential surface speed between transfer roller 12 and form roller 90 the amount
of ink applied to plate 112 may be regulated.
[0043] Within limits, if the surface speed of transfer roller 12 is increased, the ink film
104 is presented at the inking nip N at a faster rate and more ink is transferred
by the surface of roller 90 to lithographic printing plate 112, and the opposite is
true, if the surface speed of roller 12 is decreased.
[0044] The film of ink 104, existent between adjacent surfaces of rollers 12 and 10, permits
the rollers 12 and 10 to be rotated at different surface speeds in sliding relationship
because the film of ink 104 actually provides lubrication which permits slippage '
between adjacent surfaces of rollers 12 and 10 without frictional deterioration. By
reason of the slippage between rollers 12 and 10, the ink film 104 is calendared,
smoothed out, metered and distributed by shearing the ink between adjacent surfaces
of roller 12 and the film 116 on idler roller 10, to create a printing liquid film
104a. The thickness of printing liquid film 104a is controlled by the relative pressures
between metering roller 13 and transfer roller 12, and idler roller 10 and the relative
speeds of rollers 12 and 10.
[0045] Transfer roller 12 preferably is driven at a surface speed which is within a range
of for example, several hundred feet per minute slower than the surface speed of form
roller 90. For example, if a printing press has paper traveling therethrough at a
surface speed of 900 feet per minute, the surfaces of printing plate 112 and form
roller 90 will ordinarily have a surface speed of 900 feet per minute. The surface
speed of transfer roller 12 would preferably be less than 90 feet per minute.
[0046] Films 104 and 116 will be combined at inking nip N and will split when sheared as
rollers 12 and 10 rotate away from inking transfer nip N. The fresh film 104a of printing
ink adheres to the surface of idler roller 10. Ink rejected by idler roller 10 forms
a feedback film 104b of ink which may be slightly irregular. Film 104b adheres to
the surface of transfer roller 12 and is conveyed back to the ink metering nip N'
to be remetered. Feedback film 104b may not be uniform because the starved areas on
form roller 90 and consequently idler roll 10, from which ink was removed by image
areas on plate 112, removed different quantities of ink from film 104 in order to
form film 100 on form roller 90. Film 128 has starved areas 128' from ink removed
by image areas 122 on plate 112, thus rendering film 128 irregular.
[0047] Actually ink film 130 generated at nip X is quite uniform and consequently films
100 and 116 and 104a and 104b resulting therefrom will be substantially uniform as
explained later herein.
[0048] The lithographic printing plate 112 has hydrophillic or water liking non-image areas
121 and oleophillic, ink receptive, image areas 122 formed on the surface thereof.
If printing plate 112 is provided with raised image areas; the dampener 200 would
not be required to prevent transfer of ink to non-image areas.
[0049] At the nip 120 between applicator roller 90 and printing plate 112, the combined
film 216 and 100a is split to form thin films 125 of ink and dampening fluid over
oleophillic surfaces 122 on the printing plate. The layer 216 of dampening fluid is
carried on and in the film 100a of printing liquid and is also distributed to form
a thin film 226 of dampening fluid over hydrophillic areas 121 of the printing plate.
[0050] Some dampening fluid remains on the surface of form roller 90 which is moving away
from nip 120 towards nip X, but such dampening fluid as does remain thereon is transfered
with the excess liquid film 128 to become liquid film 130a on the ink roller 94. A
doctor blade 26 has one of its edges supported by holder 28 and a second edge engaging
roller 94 for removing as much of the excess liquid from the roller as possible thereby
forming a uniform and thin film 130b on roller 94. The removed dampening fluid and
ink (liquid) is gravity fed onto a deflector shield 30 which in turn permits gravity
feed into a liquid reservoir 14a in ink pan 14.
[0051] The non-uniform excess liquid film 128 remaining on form roller 90 is combined with
the ultra thin uniform film 130b on ink roller 94 and actually "printed" onto roller
94. Explained again, the excess ink and dampening fluid 128 remaining on the surface
of form roller 90, after printing to the lithographic printing plate 112, is. virtually
entirely removed therefrom by transferring or "printing" the irregular film 128 to
the ultra-thin doctored film 130b on the surface of idler roller 94. The ultra-thin
and uniformly doctored film 130b is formed from a reservoir 23 of accumulated excess
ink 130a. Idler roller 94 now functions as an endless doctoring surface which allows
the film 128" to be completely transferred to the surface of roller 94 just as ink
film 100a was initially transferred or "printed" to the plate 112.
[0052] The layer of dampening fluid 216 is applied in substantially the same manner as the
ink film 100 is applied. An excess of dampening fluid 214a is supplied to bead 201
and metered at Na between rollers 213 and 212 to form a film 204 of dampening fluid
which is applied to ink film 100a on form roller 90 at nip
D. The film 204 of dampening fluid on hydrophilic dampening fluid transfer roller 2l2
and dampening fluid in film 100a combine at nip D to form film 216 on form roller
90. The film 217 of excess dampening fluid is removed from form roller 90 and is returned
to bead 201 to be remetered at nip Na.
[0053] From the foregoing it should be readily apparent that the improved apparatus for
applying ink to printing systems offers control of metering at ink metering nip N
and N' to provide a film 100 of ink of precisely controlled thickness by adjusting
pressure between rollers 10, 12 and 13, and futher by controlling surface speeds of
rollers, 12 and 10 relative to each other. The rate at which the metered film 104
of ink is offered to film 116 on idler roller 10 at inking nip N and also the hydraulic
force of obtaining the desired film split are controlled.
[0054] To eliminate conditions which could cause accumulation of ink, when printing unusual
forms or on only one-half of a web, rendering it impossible to form a film 100 of
precisely controlled thickness, the doctor blade 26 engages roller 94 to remove as
much as possible of the ink and dampening fluid in film 128. When roller 94 engages
roller 90 a thinner uniform thickness of printing liquid 130 moves into nip 106 and
thereby assists in preventing an accumulation on idler roller 10.
[0055] As best seen in FIGS. 1 and 2, the mixture of dampening fluid and ink thus removed
by doctor blade 26 is fed by gravity onto deflector shield 30 and from there into
ink pan 14. Ink pan 14 has a central drain outlet 14b located in the center of pan
14, which communicates through appropriate pipes 14c and pump 32, driven by motor
34, to distributor-tube 20 to regulate the flow of printing liquid onto metering roller
13 at 22. The provision of the bottom in pan 14 with sections sloping downwardly toward
the central opening assures constant circulation of ink 14a in- the pan. The ink flows
from tube 20 into the center of nip N' forming excess 22 and then flows outwardly
along nip N' to cascade over the ends of metering roller 13 and transfer roller 12
into opposite ends of pan 14. Thereafter, the ink is mixed with the contents of the
reservoir including the non-uniform mix of ink and dampening fluid removed from roller
94. A bypass line 38 is branched from distributor tube 20 to discharge printing liquid
into ink pan 14. Thus, by continuous operation of pump 32, a substantially homogeneous
mixture of ink and dampening fluid is provided as printing liquid 22 and deposited
onto metering roller 13 and/or transfer roller 12.
[0056] Tests have revealed that when printing at 900 feet per minute using a two plate wide
lithographic newspaper press, approximately one-thirtieth gallon per minute of letterpress-type
ink was printed onto a web which was thirty inches wide. The plate printed directly
to the web.
[0057] The pump 32 delivered two gallons per minute of a homogeneous mixture of ink and
dampening fluid through line 38 to reservoir 14 and three gallons per minute through
distributor tube 20 to the nip N'. Thus, the pump capacity was five gallons per minute
which was sufficient to maintain a homogeneous mixture of ink and dampening fluid.
The flow of three gallons was sufficient to prevent separation of dampening fluid
from ink in nip N' or to remove any dampening fluid from nip N' that was separated
from the ink. Thus, dampening fluid was not present in nip N' in a form which would
displace ink and cause stripping.
[0058] To replenish the printing liquid used in the system, an ink supply tank 40, FIG.
3, is provided in the circulating system with a pump 42 having an inlet in communication
with the fresh ink and an outlet in fluid communication through line 41 with a float
valve 44 which permits communication with distribution tube 20. Float valve 44 is
controlled by a float 46 disposed within ink pan 14 to add fresh ink to liquid 14a
when the level of liquid drops below a predetermined quantity. Since float valve 44
is closed except when the level of ink in pan 14 is low, a return line 41a having
a valve 41b therein extends between ink supply line 41 and ink container 40 to permit
circulation of ink from pump 42 through supply line 41 and return line 41a when float
valve 44 is closed.
[0059] Further, when desired, this circulation system is operable on a complete printing
couple as shown in FIG. 3. When employed in forward printing couples, the first printing
unit is operable as previously described in relation to the embodiment of the invention
shown in FIG. 1.
[0060] Further, for an adjacent couple in the forward printing mode only, a doctor blade
26 supported by holder 28' is disposed to engage roller 94 to remove a portion of
the ink and dampening fluid film carried thereon. This portion of ink is then gravity
fed through deflector shield 30' into ink pan 14'. Pan 14' includes ari outlet 14b'
which is in fluid communication through appropriate piping with pump 32
1 powered by motor 34' which discharges into distributor tube 20'. A control valve
36
1 is provided to control the flow of homogeneously mixed printing liquid 22' onto meter
roller 13 for application to form roller 90 and from there onto printing cylinder
P. Pump 32
1 is continuously supplying printing liquid through distributor tube 20' and the printing
liquid is then either discharged onto metering roller 13' or through bypass tube 38'
to thereby provide a continuous circulation of the printing liquid which creates the
homogeneous mixture of ink and dampening fluid for discharge as the printing liquid
22
1.
[0061] In the event that the second printing couple is used in a reverse printing mode only,
doctor blade 26' is disengaged from roller 94 and a doctor blade 26a is supported
by holder 28a for removing a portion of the ink and dampening fluid carried by roller
95. This removed portion of ink and dampening fluid is gravity fed to an ink collection
pan 14" which has a discharge outlet 14b" in fluid communication through appropriate
piping with discharge outlet 14b' and the inlet of pump 32'.
[0062] A float control valve 44' is provided with an inlet in fluid communication with the
outlet of a pump 42 driven by motor 43 and an outlet in communication with distributor
tube 20' so that fresh ink may be added to the system when necessary. Valve 44' is
controlled by a float 46' mounted within ink pan 14' so that when the level of liquid
14a' drops below a predetermined amount, fresh ink is supplied to the system. This
arrangement permits the adding of fresh ink to the system for both forward and reverse
printing by use of a single float control valve controlling the addition of fresh
ink.
[0063] It should be noted that when reversing a printing couple the direction of rotation
of roller 90 and, therefore, roller 10 is reversed although the directions of rotation
of rollers 13 and 12 may remain the same.
[0064] A second embodiment for multiple printing couples 1 and 2 is shown in FIG. 4. This
embodiment is similar to the embodiment shown in FIG. 3, except that a single pump
50 driven by motor 52 has its inlet in fluid communication through conduits or similar
piping with the outlets of pans 14, 14' and 14". The outlet of pump 50 is in fluid
communication through conduits or similar piping through a mixing tank 54 which receives,
mixes and stores a quantity of the printing liquid. Stirring apparatus 56 having paddles
58 disposed within the printing fluid 55 continuously mixes the fluid to ensure a
homogeneous mixture of ink and dampening fluid for the printing liquid used in the
printing system.
[0065] A quantity of fresh ink is stored within tank 60 which includes an outlet 62 in fluid
communication through appropriate piping to a float valve 64 disposed in fluid communication
within tank 54 to add fresh ink to the printing liquid 55 when needed. A second pump
66 driven by motor 68 includes an inlet in fluid communication through appropriate
piping with the interior of tank 54 and outlet in fluid communication through appropriate
discharge tubes 20 and 20'.
[0066] In this embodiment, pump 66 has a discharge sufficient to provide the required amount
of flow of printing liquid to metering rollers 13 and 13' with some flow through bypass
tubes 38 and 38' into ink pans 14 and 14', respectively. Further, this embodiment
in addition to a single pump moving the homogeneous printing liquid to both metering
rollers 13 and 13', includes a separate and distinct mixing apparatus to ensure that
the ink and dampening fluid is continuously mixed to provide a homogeneous mixture
of printing liquid 55.
[0067] The third embodiment of the invention illustrated in FIG. 5 is preferred for multiple
printing units which incorporates the system and described in relation to the second
embodiment illustrated in FIG. 4.
[0068] In this embodiment, six printing couples 1-6 (three printing units) are illustrated
with the first printing unit being capable of forward and reverse printing. It will
be noted that couple 2 is illustrated with blade 26a·positioned for reverse printing.
[0069] As illustrated, a single tank 54' is provided for receiving a quanity of printing
liquid 55' therein. Mixing apparatus 58' is then used for continuously mixing the
ink and dampening fluid contained within the mixing tank 54' to ensure a homogeneous
mix of printing liquid from removed ink and dampening fluid from a multiple of printing
units. Further, a remote supply tank 60' is provided for supporting a quantity of
fresh ink and an outlet 62' is in fluid communication through appropriate piping to
a float valve 64' disposed within tank 54' for adding the fresh ink into the printing
liquid 55' when necessary.
[0070] Each printing unit shown in FIG. 5 is then in fluid communication through appropriate
piping to return and supply pumps in a manner similar to that previously described
in relation to the embodiment illustrated in FIG. 4.
[0071] In this embodiment, varying combinations of printing, having varying mixes of excess
ink and dampening fluid; namely, couples running forward and reverse, couples running
half-webs and those having ordinary and extraordinary printing formats, are joined
together by removal of excess ink and dampening fluid from respective form rolls of
each printing couple, circulated and mixed with fresh ink to form a homogeneous mixture
of printing liquid and then distributed back to each printing unit.
[0072] Extensive testing has revealed that at no time was "greying" noticed throughout the
period of test runs which lasted several hours and ink used on one day could readily
be used again. It was seen that emulsification in printing is not a detriment when
controlled as described herein. Dampening fluid when properly dispersed in ink had
shown that it can be beneficial and not a contaminant to the lithographic printing
process.
[0073] It should be appreciated that filters could easily be added to this system for removal
of foreign particles of dried ink, dust paper lint, etc. which if allowed to accumulate
could cause problems in addition to those primarily solved by this invention. The
system also readily provides that ink additives and ink heating and/or cooling may
be incorporated for any purpose required, primarily at tanks 54 or 54'.
[0074] It should be appreciated also that other and further embodiments of the invention
may be devised without departing from the basic concept thereof.
1. A method of applying an emulsified printable mixture of ink and dampening fluid
to a lithographic printing plate comprising the steps of: depositing an excess of
the emulsified mixture of ink and dampening fluid in a central portion of a nip between
a transfer roller and a metering member such that the emulsified mixture flows longitudinally
of the nip toward opposite ends of the roller; rotating the roller to meter a thin
film of the emulsified mixture between the metering member and the roller onto the
surface of the roller; delivering the film to the lithographic printing-plate; maintaining
flow of the mixture longitudinally of the nip to prevent accumulation of the dampening
fluid adjacent said nip; and removing the mixture from the nip adjacent opposite ends
thereof.
2. The method of Claim 1 with the addition of the step of: adding a portion of a second
emulsified mixture of ink and dampening fluid which was not transferred to a lithographic
printing plate with the first mixture; and mixing the first mixture with the second
emulsified mixture to form a homogeneous mixture, said homogeneous mixture having
a smaller percentage of dampening fluid than the second emulsified mixture.
3. The method of Claim 1 wherein the step of removing the mixture comprises: causing
the mixture to cascade over opposite ends of the roller.
4. The method of Claims I or 2 or 3 with the addition of the step of: depositing the
mixture removed from the nip adjacent opposite ends of the roller into opposite ends
of a reservoir; removing the mixture from a central portion of the reservoir such
that the mixture flows from opposite ends of the reservoir toward the center of the
reservoir; and depositing the mixture removed from the central portion of the reservoir
in a central portion of the nip between the roller and the metering member.
5. The method of Claim 4 wherein the step of removing the mixture from a central portion
of the reservoir comprises: pumping the mixture to the central portion of the nip.
6. The method of Claim 5 wherein the step of pumping the mixture comprises the steps
of: pumping a portion of the mixture through a first line to a central portion of
the nip; and pumping a portion of the mixture into the reservoir such that the mixture
is removed from the reservoir at a faster rate than it is deposited in the central
portion of the nip.
7. The method of Claim 6 with the addition of the step of: delivering fresh ink to
the reservoir to replenish the mixture applied to the lithographic printing plate.
8. The method of Claim 5 wherein the step of removing the mixture from a central portion
of the reservoir comprises: removing mixtures from a central portion of a plurality
of reservoirs; mixing the mixtures to form a homogeneous mixture; and pumping the
homogeneous mixture to central portions of a plurality of nips.
9. In a printing system having a printing plate, a form roller engaging the printing
plate, and apparatus to apply ink and dampening fluid to the form roller, the improvement
comprising: means for removing excess ink and dampening fluid from said form roller
after said form roller engages the printing plate; means for mixing ink and the excess
ink and dampening fluid removed from the form roller into a substantially homogeneous
printing liquid; metering means having a metering nip for supplying the substantially
homogeneous printing liquid to said form roller after the excess ink and dampening
fluid are removed from the form roller; and pump means circulating said homogeneous
printing liquid to and from said nip to assure that any dampening fluid which is separated
out of said homogeneous printing liquid is removed from said metering nip.
10. The printing system of Claim 9, wherein said removing means further includes a
doctor blade, and means for directing flow of removed ink and dampening fluid to said
mixing means.
11. The printing system of Claim 9, wherein said metering means includes a container
for supporting a quantity of ink and the removed ink and dampening fluid, and pump
means; and said mixing means includes means directing the removed ink and dampening
fluid through said container to form the substantially homogeneous printing liquid.
12. The printing system of in Claim 9, wherein said metering means includes a container
for supporting a quantity of ink and the removed ink and dampening fluid, means for
mixing the ink and removed ink and dampening fluid in the container to form the homogeneous
printing liquid, and pump means to supply the substantially homogeneous printing liquid
to the metering nip such that the printing liquid flows longitudinally of the nip.
13. The printing system of Claim 12 said pump means comprising: means to dispense
printing liquid into a central portion of said metering nip, said metering means being
positioned such that printing liquid flows longitudinally of said metering nip at
a rate sufficient to prevent accumulation of said dampening fluid in said nip.
14. A printing system as set forth in Claim 9 or 10 or 11 or 12 or 13, said apparatus
to apply ink and dampening fluid to the form roller including a hydrophilic roller
delivering a film of dampening fluid to said form roller and removing excess dampening
fluid from said form roller.
15. A printing system as set forth in Claim 14, with the addition of a dampening fluid
metering roller in pressure indented relation with said hydrophilic roller to form
a dampening fluid metering nip, the excess dampening fluid removed from the form roller
by the hydrophilic roller being carried by the hydrophilic roller to the dampening
fluid metering nip; and means to maintain an abundant supply of dampening fluid adjacent
said dampening fluid metering nip.
16. Inker apparatus for continuously, selectively and uniformly applying a film of
fluid newsprint type ink to a lithographic printing plate comprising: an ink metering
means; an ink transfer roller having an oleophilic ink recepteive surface; an ink
applicator roller having an ink receptive surface urged into pressure relation with
said ink transfer roller to form an ink transfer nip; a form roller engaging the printing
plate, said form roller having an ink receptive surface urged into pressure relation
with said ink applicator roller to form a nip; means supporting said ink metering
means and said ink transfer roller in pressure relationship to form an ink metering
nip between adjacent surfaces of the ink metering means and the ink transfer roller;
speed control means secured to control the surface speed of said ink transfer roller
relative to the surface speed of said form roller to maintain the surface speed of
the transfer roller less than the surface speed of said form roller; ink supply means
to supply an excess of ink to said ink metering nip to replenish ink on the surface
of the ink transfer roller which is moving from the ink transfer nip to said ink metering
nip; means engaging the surface of a film of ink and dampening fluid on the form roller
surface which has just moved from the printing plate to remove excess ink and dampening
fluid from the surface of the form roller and to direct the excess ink and dampening
fluid to the ink supply means; and means to maintain a flow of ink to and from said
metering nip at a rate to prevent separation and accumulation of dampening fluid.
17. The inker apparatus of Claim 16 with the addition of a hydrophilic roller delivering
a film of dampening fluid to said form roller and removing excess dampening fluid
from said form roller.
18. The inker apparatus of Claim 13, with the addition of a dampening fluid metering
roller in pressure indented relation with said hydrophilic roller to form a dampening
fluid metering nip, the excess dampening fluid removed from the form roller by the
hydrophilic roller being carried by the hydrophilic roller to the dampening fluid
metering nip; and means to maintain an abundant supply of dampening.. fluid adjacent
said dampening fluid metering nip.
19. In a lithographic printing system including a lithographic printing plate carried
by a plate cylinder, a form roller applying ink and dampening fluid to the printing
plate, an inker applying ink to the form roller, and a dampener applying dampening
fluid to the printing plate, the improvement comprising: a reservoir of ink, said
reservoir being adapted to maintain an abundant supply of ink to the inker; and ink
circulation means to remove dampening fluid and ink from said reservoir and to return
a homogeneous mixture of ink and dampening fluid to said reservoir.
20. The lithographic printing system of Claim 19 with the addition of: means for removing
excess ink and dampening fluid from said form roller after said form roller engages
the lithographic printing plate; and means to mix the excess ink and dampening fluid
removed from the form roller with the dampening fluid and ink from the reservoir to
form said homogeneous mixture of ink and dampening fluid returned to said reservoir.
21. The lithographic printing system of Claim 19 or 20 wherein the dampener comprises:,
a hydrophilic roller delivering a film of dampening fluid to said form roller and
removing excess dampening fluid from said form roller; and dampening fluid metering
means to form said film of dampening fluid on said hydrophilic roller.
22. The lithographic printing system of Claim 19, said reservoir of ink comprising
a reservoir of newsprint type ink.