CA2049277A1 - Keyless printing system for keyless lithographic printing - Google Patents

Abstract

- i -ABSTRACT OF THE DISCLOSURE
In a keyless lithographic printing press having blanket cylinder (10) and plate cylinder (15) with printing plate mounted thereon, an improved keyless printing systems having: a system (14) for supplying dampening water to the plate cylinder (15) at least one form roller (16) in rotational contact with the plate cylinder (15); inking drum (11) in rotational contact with the form roller (l6); at least first and second transfer rollers (13, 17) in rotational contact with the inking drum (11); metering roller (20) having at least an oleophilic And hydrophobic surface which retains quantity of printing fluid, the metering roller (20) being in rotational contact with the first and second transfer rollers (13, 17); and a system (30) for supplying printing fluid to the metering roller (20).

Description

2 ~ 4 9 2 7 ~

~ACKGR~p OF_THE INVEN~ION
The present invention relates to prlnting systems for use in keyless lithographic printing pro~esses.
In the field of high ~peed lithographic prlnting, ink 18 ~ontinuously conveyed from an ~nk ~ource by means of a series of rollers to a planographi~ printing plate on ~ plate cyl~nder in a lithographic printing press~
Image portion~ of the print~ng plate a~cept ink from on~
or more of the last of a ~eries of inking roller6 and transfer a portion of that lnk to a blanket cylinder as ~ reverse image from which a portion of the ink is trans~erred to form a correct-reading image on paper or other materlals. It is also ~ssential in oonventional lithographic printing processes that a dampening ~olution containing water and proprietary additives be conveyed continuously to tha printing plate whereby transferring ln part to the non-image areas o~ the prlnting plate th2 water functions to keep those non-image areas free of ink. Hereinafter, the terms "water" and "dampenins solution" refer to water plus additives or to other aqueous solutions used in the operation of lithographic print~ng presses.
In ~onventional pr~nting press systems, the ink ~s continuously made available in varying amounts determined by ~ross-press column input control adjustments to all parts of the printing plate, ~ncluding both image ~nd 2~ 27~

non-image areas. In the ab~ence o~ the dampening ~olu~ion, the prin~ing plate will accept ink ~n both the image Rnd non-image areas of lt~ ~urfa~e.
Lithographl~ printing plate surfaces in the absence of imaging materials have minute interstices and a hydroph~lic or water-loving property to enhanoe retention of water, that ~ the dampening solution, rather than ink on the sur~ace of the plate. Imaging the plate creates oleophilic or ink-loving are~s according to the imag~
that i8 to be printed. Consequently, when both ink and dampening solution are presented to an imaged plate in appropriate amount~, only the ink tending to reside in non-image areas becomes disbonded from the plate~ In general, this action accounts for the oontinuous ink and dampening solution d~fferentiation on the printing plate surface, which is essential and integral to the lithographic printing prooess.
Controlling the correct amount of dampening solution supplied during lithographic printing has been an industry-wide problem ever since the advent of lithography. It requires continual operator attentivn since each column adjustment of ink input may require a change in dampener input. Balancing the ink ~nput that varies for each column across the width of the press with a uniform dampening solution ~nput across the w~dth o~
the press is at best a oompromise. Consequently, 7 ~

dependin~ upon whic:h por~ion s:~ the ima~ the operator has adopted as his ~tandard of print qual~ty at any giv~n time during the printing run, the operator may need to adju~t the ink lnput at correspond~ngly located cross-pres~ posltions. A~ a resulk, the dampening ~olution to ink rat~o a~ that posltion ~ay ~e~ome changed rom a desired value. Conversely, the operator ~ay ad~ust a dampener lnput ~or best ink and ~ampen~ng solution balance at one ~nking column, which may adversely ~fect the ink ~nd damp~nlng solution balance at one or ~ore other cross-press lo~ations. Ad~ustments such as these tend to occur repeatedly throughout the whole press run, resulting in 61ight to 6ignlf~cant difference~ ln the quallty of the printed ~mage throughout the run~ In carrying out these ad~ustment operations~ the resultiny images may or may not be commerc~ally acceptable, leading to waste in manpower, materials, and printing machine time.
C~rtain commercially ~uccessful newspaper printing configurations rely on the inklng train roller~ to carry dampening solution directly to the printing plate.
~otable among these are the Gos~ Hetro, ~oss Netroliner, and the Goss Headliner Offset printing presses whlch are manufactured by the Graphic Systems Division ~f Ro~kwell International Corporation. In these alternative ~onf~gurations, the dampening solution is ccmbined with ' ": '' ,:

the ink on ~n inking os~illator drum ~u~h that both ink ~nd water .Ire subsequently and continuously transferred to the inking for~ roller~ for deposition onto the printl~g plate. In another varlat~on~ the dampening 801ution i applied ln a conv~ntional manner dir~ctly to the printing plate by means of ~eparate dampening roller~
and a dampening solu~ion ~upply system. In ~y~tems of either type, regardles~ of the method whereby the dampen~ng 601ution ~s introduced, it is well known that some of the dampening solution becomes mixed with the ink and returns to the inking traln of rollers and may ultimately be introduced into the ink ~upply system itself. In any case, these conventional lithographic ystems require considerable operator attention to tend to maintain ink and dampening solution balance and~produce more product waste than desiredO
Prior art devices and methods for correcting this inherent f~ult in conventional lithography utilize keyless inkers. Certain of these methods a~so involve ~liminating the dampening sys~em or el~minating operator control of the dampening system.
Reyless inking 6ystems have been d~sclosed that purport to ellm~nate operator attention to column control of inking by elimination of adjustable inking k~ys, there~y ~vo~ding muoh of the aforementioned disadvantages of conventional llthography. ~or keyless inking systems .,.,.; , ~ .. .

2~L.~2 an in~ ~etering ~e',hod i~ re~uired that cont~nue~ to ~unction desplte ~ne presence of up to about 40%
dampening ~olut~cn in the ink without allowing any temporarily free dampening solution to interfere with the ink-metering function. Also, the unused or non-uniform portion of the ink ~ilm that i6 ~einy continuously presented to th~ printing plate ~ust be continuously ~crapedo~ the return ~ide o~ the lnking.
system ~o enable continuous presentation of a uniform ink film to the plate by the supply side of the inking ~ystem. This s~raped-off fllm i5 not uniform ~cross tha width of the press in ink and dampening solution compos~tlon. Since it would not be e~onomically feasible to con~inuously discard the ~nk in the unu~ed portion o~
~he ink and dampening ~olution m~xture, this mixture must either be renewed by selectively removing dampening solution from the mixture and returntng the ink portion to the inking system or by thoroughly intermixing the unused ink and dampening solutlon mixture with fresh replenishment ink and returning such mixture to the inking system. U.S. Patent 4,690,055 discloses a keyless ~nking sy6te~ in which dampening ~olut~on removal is unnecessary and which accommodates the dampening 801ution that is naturally acquired in the unused ink during the practice of lithography and for which, therefore, removal of dampening solution is not required.

2~ 27~

In the keylesR inking ~y~tem di~clo~ed ~n U.S.
Patent No. 4,690,055 ~h~reb~ ~ncorporated by reference), the locat~on of the dampenir-g ~y~tem ia not critical and can be positioned either to supply dampening ~olution directly to the plate cylinder or at ~ome other location ~uch a at an osclllator drum to which ink is al~o being ~upplied. An ink circulating and ~lxing ~ystem receives new or replenishment ink, as well as ~he ink and dampening solut1on combination that is con~inuously returned from a doctor blade which 6crapes excess printing fluid from a rotating metering roller. Such lnk and dampening combinations ~re generally herein referred to as print~ng fluids. The printing fluid oirculating and mixing ~ystem functions to assure an inherantly uniform cross-press input of printing fluid that remains consistent throughout and consist~ of a printing flu~d pan roller, pump and appropriate conduits, a pr~nting fluid pan level controlling system, and a printing fluid reservoir of such volume and design that it assures the printing flu~d being fed to the metering roller is un~form in compo~itlon at any given in~tant of time despite the existe~ce of the continual cross-press dampening solution to ink ratio d~fferences of the unused or scraped return printlng fluld previously re~erred to.
The printing ~luid circulation system i~ designed to continuously collect and di~tribute the printing 1uid 2 ~ 7 ~

~rom a reservoir through a plenum or ~eries o~ vxlfices to uniorm1y r~distribute the printlng fluid ~cross the pre s width to provide uniform composition of the printing fluid that i~ being introduced to the metering roller. The metering roller can be one of th~ types shown ~nd de~crlbed in U.S. Patent Nu~ber~ 4,882,990, 4,537,127, 4,862,799, 4,567,827, or 4,601,242, ~all o~
which are hereby in~orporatea by reference) or any wear re~istant oleophilic ~nd hydroph~b~ ~eterin~ roller s sub~tantially therein defined.
Although the ~ystem disclosed in U.S. ~atent 4,690,055 provides great improvements in lithographic print~ng presses, the technology requires a rather large and cUmberBome ~n~ pan arrangement th~t iB more-or-less open t~ the press room environment. It requires that the pan be disposed beneath the metering roller/doctor blade ~onfluence 60 that scraped off ex~ess and return printing ~luid film will fall readily into the pan arrangeme~t.
Pan roller or metering roller replacement is inconvenient and time consuming because of the large pan Bize and its peripheral attachmentE. Additionally, the pan roll~r requires a ~eparate motor to drive it nominally ~t a speed slower than the press speed metering roller. Due to the more-or-less open nature of the pan system, the pan r~ller which dips into the pool of print~ng fluid cannot be driven at press epeeds be~au~e pr~ntlng ~luid 2 ~ 7 7 would be propell~d from lt~ sur~ace ln many dlrectlons, lncludlng outs~de of the pan reglon~ lnto th~ pre~room~
A1BO~ the 81~w ro~atlonal movement ~f the pan roller ~au~es undue and sever~ ~sar on the ~eterlng roller ~urface ~h~n th~ two ~re ln lndented rel~tlonsh~p~
Consequently, the pall roller/meterlng roller ~onfluence mu~ e a gap. C!ontrol of that gap to avoid meter~ng roll~r wear and yet ~lmultaneou~ly assure ~omplete fllllng of the ~eterlng roller cells 1~ difficult to englneer and to control over long period~ of runniny tlm~. For instance, depending upon flow proper~esofthe ink be~ng u~ed, the cells may or may not beoome ~ompletely filled when non-forclng ~ondlt~on~ such a~ ~
gap between the pan roller and the ~elled roller are u~ed or when lnk lnput ~ystem~ not u~lng pan r~ller~ are employed.
~ ependlng upon the parti~ular metering roller technology belng employed, the ~low-mov~ng pan roller runnlng ln ~ontact with the rap~dly turning meterlng roller that 1~ rotating at press speed, may rapldly wear away the h~rd but abradable oleophlli~ and hydrophob~c metering roller ~urf~ce, thereby negatlng that element's necessary contrlbutlon to succe~Eul keyle~ llthographlc lnklng operation. Under ~everely worn cond~tlons, the metering roller may become hydroph~l~o whloh all~ws the 2~ 27~

dampening water to lnterfere with uniform and ~f~icient metering ~f ink into the sy~m or it may lose ~t~
capa~ity ~o retain ink by loss of the celled ~urf~ce ~orphology. Accordingly, there exists a need for a lithographi~ keyle6s ink~ng or printing ~luid system that e~braces all the required operational ~eatures d~sclosed by U.S. Patent 4,690,Q55 but which overcomes the perceived neg~t~ve features, namely large pan res~rvoir size with the attendant large ink volume requirement associated with use of the pan roller and reservoir, and those associated with potentially rapid wear of metering rollers or inefficient filling of metering roller cells because o~ the gap with the pan roller. Obviously, these may restrict the range o~ metering roller te~hnologies which ~an be advantageously employed.
The present invention overcomes the af~rementiGned problems, difficulties and in~onveniences, yet retalns all o~ the prlnciples esæential to keyless lithographi~
6ystems as disclosed ~n U.S. Patent 4,690,055.
Accordingly, in this improvement thQ pan and pan roller are eliminated and ~at least two transfer rollers ~re ~mployed between the metering roller and an ~n~lng drum in the in~ing train of rollers.

2 ~

5UMMARy OF THE INVENTION
An ob~ ect of the present inventiorl i8 to pxov ~ de an improved 3ceyle ~ lithograpllic printing ~ystem having more transfer roller~ in the ink~ ng train than ar~ required in prior art keyless l ~ thograph~c pr~nting ~ystems .
It 18 ~no'cher ob~ect to increase the u~e~ul li~et~e of the ~etering roll~r by providing press ~peed inX
transfer roller6 in plaee of prior art slow moving pan rollers.
It is a further object of the present invention to provid~ a pair of transfer rollars operating on the ~etering roller for effecting printing having greater uniformity of optical density than 1B achieved ~n pri~r art keyless lithographic printing systems.
It ~s another object of the present inv~ntion to provide an improved keyless lithographic printing system which eliminates the pan roller of the inker disclosed in U. .S. Patent 4,6909055, yet closely approximates the advantageous attributes of this prior art pan roller inker system.
It is another object of the pxesent invention to provide simplified and 6tructurally ~maller ink input and c~rculation $ystem components which function to assure that the process-generated, natural water content of the ink is maintained in a homogenized condit~on, thereby avoiding buildup of free water anywhere in the inking ~ 2~92~7P~

system.
~ nother principle objec~ of the present invention is to provide an improved keyless lithograph~c ~ystem having greater latitude ln the sele~t~on of usePul ~etering roll2r technologie~.
The ob~ects are achieved by an improved keyless printing ~ystem for use ~n a keyless lithographic printing press of the type having a blanket cylinder and a plate cylinder with printing plate mounted thereon.
The improved keyless printing system comprises: a means for supplying dampening water to the plate cyllnder: at least one form roller in rotat~onal ~ontact w~th the plate cylinder: lnking drum in rotational contact with the form roller: at least first and second ~ransfer rollers in rotational contact with the inking drum:
etering rollex having at least an oleophilic 2nd together with a coacting ink doctoring blade hydrophobic surface which~retains a quantity of printing fluid for transfer by means of rotational contact with the first and second transfer rollers: and means for supplying printing fluid to the metering roller. In a preferred em~odi~ent the fir~t and ~econd tr~nsEer rollers are ~rictionally driven by at least the metering roller and have a 6urface velocity substantially the ~ame as the 6urface velocity of t~e meter~ng roller.

,. :

7 ~

~IEF ~ESCRIPTION OF T~E~R~WINÇ5 The features of the present invention which are believed to be novel, ~re ~et forth w~th parti~ularity in the appended ~la~ms. The invention, together with further ob~ects and advantages, ~ay best be understood by reference tv the ~ollowing description taken in ~on~unction with the accompanying dxawings, ln the several F~gures in which li~e reference numerals ~dentify llke elements, and in which:
FIG. 1 is a schematic ~ide view of a keyless lithographic printing press system in accordance with the present invention:
~ IGS. 2 and 3 are plan and ~levat~on views, respectively, of the printing fluid input apparatus of the present inv~ntion and of ~ me~ering roller;
FIG. 4 i~ an end view of the printing fluid input apparatus and th~ ~etering roller;
FIG. 5 is a partial plan view of the printing fluid input apparatus;
FIG. 6 i6 an end view o~ the metering roller and the printing flu~d input apparatus in an open servic$ng po~ition:
FIGS. 7, 8 and 9 are a plan view, an elevation v~ew and a side view of a gage assembly used in the present invention:

2~27~

FIGS. 1~ and 11 ~r~ ~ pl~n vl~w ~nd ~n elev~tlon ~lew of ~ ~e~l oap ~semb1y ~ed ~s~ tlle present lnventlon~
~ IGS. 12 ~nd 13 are schematic repreRentatlo~ of pressurlzed pr~nting ~luld clrculat~on system~ used wlth the present inventlon:
FIGS. 14-17 are ~hematl~ ~lde Ylew~ ~f embodlments of the present lnventlo~ havlng 8 doct~r blade and return in7c ~atch pan (FIG. 14), an ln~e~tor or extruder ink inpu~ element (~IG. 15) t an gnk lnput shoe or ra11 Q~eme~t (~Ia. 16) and a doctor bl~de and return lnk catch pan ~lth slngle form roller ~IG, 17)s F~G. 18a i~ a s~hematic ~lde vlew of a prlor art ~y~em according to U.S. Patent 4,690,05~
~ 1~.. 18b illustrates an experimental configuration similar to the previously clted ~055 patent but with the pan roller moved just out of indented relation with the meter~ng roller.
FIGS. 18c and lBd nre ~chema~l~ slde v~ews ~f experlmental oonflrguratlons havlng added rlder rollers~
FIG. 18e ~ 8 a sohematlc s~de view o the preferred e~bodlment of the pre3ent ~nvention havin~ two transfer rol ler~ 7 FIG. 19 1~ a table o~ experi~en'cal ~esu1t~ of prlntablllty ~o~nparlng the coniguratlon~ of F'It So 18a through 18e and FIG. 2~ 1~ 'carget plate format u~ed 1n te~tlrlg the conlg~rat~on of ~IGS. 18~ through 18e.

2~d~27rl' DESCRIPTION OF T~E~PREF~RRED ~MBODIMENT
A keyless inking ~ystem in¢orporating the present invention is depicted in FIG. 1 in which a blanket ~ylinder 10 prints on a web traveling as indicated by ths directional arrow 12. Referring first to the dampening and inking ~ystems associated wlth blanket cylinder 10, a plate cylinder 15 is contacted by two ink form rollers 16 which ~re in turn contacted by a ~etering roller 20 via drum 11, such as a copper d~um, and two trans~er rollers 13. The ink ~etering roller 20 is preferably of the type disclosed in U.S. Patent Numbers 4,862,79g, 4,882,990, 4,537,127, 4,567,827 or 4,601~242 which were cited previously. In the dampening arrangement associated with plate cylinder 15 there typically is provided a rubb~r dampener form roller 19 and an oscillating transfer roller 2~, which may be copper covered or chrome covered. The water is contained in a pan tray 23 and a pan roller 24 is used to pick up water from the pan 23 to bring it into contact with, for instance, a spiral brush roller 25 that is rotating at a fipeed which is different relative to the speed of rotation of pan rolier 24. It should be recognized that virtually any known dampening system can be used with the present invention.
With this or other arrangements dampening solution is transferred onto the transfer roller 22 and from ther~

2~l~9~77 to t~e dampener form roller ~9. The ~orm roller 19 i5 typically position~d in a water-first sequence so that, during each revolution o~ the press subsequent ~o transferring ink to the blanket cylinder 10, plates ~re ~irst subjected to dampening solution from the dampener form roller 19 before renewed printing fluid is applied to the imaged Eurface of the plates by means of the rubber covered ink ~orm roller6 16.
A significant part of the present invention is the inking system that is used to supply printing fluid to the plate and blanket cylinders 15, 10. This ~ystem9 makes it possible to supply a uniform mixture oP ink and naturally occurring dampening ~olution to the plate cylinder 15 and thereby maintain the high print quality characteristic of conventional lithographyO In this ar-rangement the printing fluid input and circulation system is identified generally by the numeral 30 and is used to deliver ink containing dampening solution, also rePerred to as the printing fluid, to the metering roller 20.
Dampening solution in this system ~s not deliberately added to the ink but rather result naturally ~rom ink coming in cont~ct wi~h dampening solution on the printing plate cylinder 15 and which, by means of the unused or return portion oP printing fluid that passes or transfer~
ba~k down through the various rollers, in part eventually enters the printing fluid input system 30.

2 ~ l~ 9 2 7 ~

The prir.ting fluid ~nput ~pparatu~ of the zystem 3~
of the pr~,e~t invention i8 depict~d in ~n open ~arvicing position r~latlve to the metering roller 20 in FIGS. 2 and 3. An end view of the ~pparatus enyaged with the ~etering roller 2~ in ~ clo3ed operating position i~
depicted ~n FIG~ 4. The me~ering roller 20 ha~ ~irst and ~econd ends 32 and 34 which rotate ln frame~ 36 and 38, respectively. The meterlng roller 20 hag a surface 40 intermediate the fir~t and second ends 32 and 34, the surfa~e 40 capable of retalning a qu~ntity of printing fluid. A housing 42 has an open rirst 6~de 46 which mates with at lea~t a portion of the sur~ace 40 ~ the metering roller 20. When the housing 42 is in the closed operating position a ~hamber 44 is ~ormed which contains the printing fluid under a predeterm~ned pressure.
At least first and second end ~eal assemblies 48 and 50 are mounted on first and second opposed ends 52 ~nd 54, respect~vely, of the housing 42. Each of the first and second end seal assemblies 48 and 50 have at least a first surface 56 for mating with first and second end sections 58 and 60, respect~vely, of the metering roll~r 20.
Referring now also to FIGS. 4 ~nd 5 a reverRe angle doctor blade 62 i~ attached to a 6econd side 64 of the housing 42 and has an edge 66 for ~ontacting the surface 40 of the metering roller 20 and for removing exoess 2 ~ l~ 9 ~ 7 7 prlnting fluid adherir.g tD the surface 40 as the me ering roller 20 rotate~ pas'. the printing fluid filled chamber 44. A ~ealing membex 68 is att~ched to a third ~ide 70 of the ~ousing 42 and has ~ Rurface srea 72 ~or 6ubstantially ~eallng tha chamb~r 44, at laast the surface area 72 of the ~ealing member 68 being ad~acent the sur~aoe ~0 of the metering roller 20 ~uch that ~n edge 74 o~ the seal~ng memb~r 68 extends into the ~hamber 44. In a preferred embodiment the sealing member 68 is ~ubstantially longer and more flexible than the reverse angle doctor blade 62.
Since the printing fluid in the ~hamber 44 is under pressure it is a feature of the present invention that the reverse anqle doctor blade 62 is held against the surface 40 of the metering roller 20 at least in part by this pressurized printing fluid in the chamber 44.
It is w~ll known in the art of printing presses to provide devices which cause selected rollers or ~ylinders to oscillate ~for example the roller oscillation drive disclosed in Goss Metrol~ner Parts Catalog No. 280-PC, Referring again to Figure 1, Figure 280-56). ~ in ~the present invention such a means ~or oscillat~ng 76 can be attached to the metering roller 20, thus providing oscillat~on to the metering roller 20, while the housing 42 of the printing fluid input apparatus 30 remains stationary. Th~ metering roller 20 i~ o~ the type having ~n oleophilic and hydrnphobic 2 ~ 7 urface.
Depending upon the applic~cion it may or may not be necess~ry to prov~ds o~cl.l.la~ion to the metering roller 20. However, it i8 ~ novel fsature of the present ~nvention that ~n those ~ppll~ation~ where ~t i~
desirable to provide oscillat~on to the ~etering roller 20 it ~ fea~ible to accomplish this with the printing fluid input apparatus of the present invention.
The sealing member 68 may, for instance, be formed o~ steel or plast~ and have a width in the range of approximately 1 to 2 inches and a thickness in the range of approximately 0.004 to o.OI inch selected as a function of the open f~rst side dimension of the housi~g 42 and of the diameter of the meterlng roller 20 which mates w~th the open first side, ~uch that the sPaling member 6~ properly seals the chamber 44. The reverse angle doctor blade 62 may be formed of steel or plasti~
and in general have a width of approximately 1 inch and a thickness in the range of approximately 0.004 to 0.01 inch, if steel, and 0.04 to 0.06 inch, if plastic.
As 6hown ln FIG. 6 the housing 42 is attached to a ~upport 80 which ~ 5 pivotable about axis 82 and thus provides an open servicing position and a closed operating position. The housing 42, as well as metering roller 20, are shown in the open ~ervicing position in FIGS. 2 and 3, FIG. 2 being a plan view and FIG. 3 being 2 ~ ~

elevation view.
The print~ng fluid ~nput apparatu~ ~urther ~nclude~
at lea6t one inlet mean~ 102 in the housing 42 for inputt~ng prin~ing 1uid into t~e chamber ~4 and at least on~ outlet means ~04 ~n ~he hous~ng 42 for ou~putting printing fluid from the chamber 44. Since the chamber 44 i sealed by the ~etering roller 20, the first and ~econd end assemblies 48 and S0, the reverse ~ngle doctor blade ~2 and the sealing member 68, lt is thus possible to keep the printing fluid under a predetermined pressure. In the preferred embodiment, as will be discussed below, a circulating ~ystem ~s used to pump the printing fluid through the housing 42. It ~s an important fe~ture o the present lnvention that, ~ince the printing fluid is under pressure, the printing fluid circulation system is totally independent of the force of gravity as opposed to prior ~rt systems that rely on the printing ~luid falling into a reservoir or catch pan.
Therefore, the hous~ng 42 c~n be located anywhere around the circumference the metering roller 20. This has significant and ~mportant advantages in the art of keyless lithographic printing pres~ design. It allows for pr~ntlng couples of a press to be inverted thereby shorting the length of the paper path between the couples, as well as, provid~ng ~avings in space ~nd materials of construct~on. Th~s freedom to locate the 2V~77 housing 42 anywhere around th~ oircumference of the metering roller 20 provides a degree oP Preedom in design of the printing press not ound in prior art keyless printing pres6es.
Furthermore, the hous~ng 42 ~an ~e desi~ned to extend the ~ull axial length of the surfa~e 40 oP the ~etering roll~r 20 or to extend only over ~ portion of the ~urfaoe 40. For ~xample, a num~er of hou~ings, each less than full press w~dth, can he located on one metering roller. Also, the houslng 42 can be ~tructured to wrap around the circumference o the ~etering roller 20 to greater or lesser extents depending upon the criteria ~f the pre~s being deslgn.
Referring now to FIGS. 10 and 11, each of the end ~eal assemblies 48 and 50 shown in FIGS. 2 and 3 has a seal 90 which is supported by a seal ~ap 92. As can be seen in FIG. 5 the 6eal cap 92 i6 att~ched to an ~nd of the housing 42, more specifically a ~eal cap assembly is attached to each end of the housing 42.
Furthermore, the present invention can include a gage assembly 94, AS ~hown in FIGS. 7, 8 and 9, which engages the hou~ing 42 with ~ loc~tlng pln 96 when the housing 42 iB pivoted into the ~lo~ed operating po~ltion for ~ccurate positioning of the housing 42 relative to the metering roller 20, see ~IG. 6. The gage asse~blies 94 are located adjacent the fir~t and ~e~ond end sections .9 2 ~ ~

32 ~nd 34 of the ~etering roller 20. The gage assembly 94 has first and second section 81, 83 which 6urround the ends 32, 34 of the ~etering roller 20.
In general a means 100 ~or press~rizing with the printing fluid the chamber 44 ln the housing 42 is connected to the hou6ing 42 via the lnlet means 102 and the outlet ~eans 104 on the housing 42.
As ~hown in FI~. 12, the means 100 for pressurizing is a clrculatlny ~ystem havlng a pump 106 with an output 108 and an ~nput 110. The output 108 ~f the pump 106 is connected to a pressure regulating check valve 111 and to the inlet means 102 of the housing 42. The input 110 of the pump 106 is ~onnected to an printing fluid reservoir 112 which is also ~onnected to the outlet ~eans 104 of the housing 42. As shown in ~IG. 12 the pressure regulatlng check valve 111 ~s alæo connected to the printing fluld reservoir 112. In the preferred embod~ment the pump 106 is driven by a constant speed drive motor 114 which is connected t~ press/unit controls 116 of the printing press. The press~unit controls 116 may also receive siqnals from a sensor 118 ~ounted in the housing 42 for 6enYing the pressure of the printing fluid in the chamber 44 of the housing 42. In one embodiment a pressure of 4-6 psi ls maintained in the ~hamber 44 to enable smooth c~nsistent printing ~luld input to metering roller 20. The pressure regulating ~heck valve 111 , 2~ 2~

functions to set the pressure o~ 4-6 p~i in the chamber 44 and allows a portion of the printing fluid to flow back lnto the printing fluld reservoir 112, as nece~sary.
FIG. 13 depic~ an alternatlve mean~ 100 for pre~surizing the ~hamber 44 wherein the pump 10~ i8 driven by a ~otor 120 which is operated ~t a speed proport~onal to the Ppeed of the printing press via varia~le ~peed drive 122. In thi~ embodiment the output 108 of the pump 106 is connected to the inlet means 102 of the housing 42 and the outlet means 104 of the housing 42 is oonnected to the printing fluid reservolr 112. The input 106 of the pump is al o connected to the printing fluid reservoir 112. Various means can be used to add fresh replacement ink to the printing fluid reservoir 112 in either the FIGo 12 or FIG. 13 embodiments as needed.
For example, the means can include solenoid valve 124 which is connected to a press/unit controller 126, the press/unit controller 126 receiving a signal from a printing fluid level sensor 128 connected to the prlnt~ng fluid reservo~r 112. It 16 a novel feature o~ the present lnvention that the printing fluid reserv~$r 112 can be locatsd at any position relative to the ~hamber 44, higher or lower than the ~hamber 44, ~ince the printing fluid flow i5 regulated by internal pres~ure rather than by the ~orce of gravity.

2al~s~7;~

In addition the present invention can include a means for ~ontrolling the temperature o~ the printlng fluid in the cha~ber 44 of the housing 42 For exa~ple, the ~eans for controlling the temperature can be connected directly to the housing 42 or can be connacted to the printing fluid reserYoir 112. The ~eans for controlling the temperature can utilize resi~tance element strip h~ater~ affixed to the huusing 42 (for example, a Chromalox No. SL0515 flexible resistive element heater). For the printing ~luid reservoir 112 an immersion heater such as ChromalGx No~ A~MT0-2155T2 can be used.
The present invention overcomes a number of prob}ems, difficulties and restrictions in prior art keyless lithographic printing systems. For instance, the pan and pan roller of the cited prior art (U. S. Patent No. 4,690,055) are replaced by a ~maller and less complicated housing that together with the metering roller surface form a completely enclosed housing.
The inks selected for use in the present invention preferably have low values of vi~cosity ~t low rates of shear ~o that the printing fluid flows readily ~s compared to conventional lithographic inks. An ink having this property readily flows into and, subsequent to doctor blade metering as herein practiced, out of the cell~ or interslices in the surface of the rapidly 2a~2'~

rotating metering roller 20 as it ~oves past the pxessurized slowly circulating printing fluid in chamber 44.
An important ~eature when us~ng a low viscosity printing fluid with the present inYention is that the ink can be gormulated to have good printing fluid transfer properties in the inking train of roller6 and yet have any of a wide range of vi~cosity v~lues at low ~hear rates, the ~ormulation being dependent upon the configuration of the various rolleræ and cylinders used in a particular printing press. This capability is not possible with prior art pan roller printing fluid input systems as the amount of fluid input to the metering roller is dependent upon ~he pan roller force and not on the printing fluid'~ mobility. T~is capabllity is also not possible without the use of oleophilic and hydrophobic metering rollers since water is ~ore readily forced out of low viscosity printing fluids and in the absence of the hydrophobic property will debond the fluid from the metering roller, thereby negating control of ink input.
In FIGS. 14 through 16, the paper web 12, blanket cylinder 10, plate cylinder 15, form rollers 16, dampening syste~ 14 and oleophilic inking drum 11 ~re all configured substantially parallel axially ~nd are more-or-less standard elements in the practice of lithographic 2 ~ 7 7 printing. Normally, and as conventionally practiced, only one transfer roller ~3 i~ required to convey the ink ~e~ered by the coacting ~etering roller 20 and blade 18 ~o the oleophilic inking drum 11 thence by ~eans of foxm rollers 16; pr~nting plate 15, and printing blanket 10 to the paper 12. The preRent invention provides and requires, in addition ~o ~he ~ir~t transfer roller 13 a second transfer roller. 17 for reason~ hereinafter explained. FIGS. 14 through 16 represent alternative embodiments of the present invention and are similarly configured except that different ink or pr~nting fluid input means 30 and locations of different dampening systems 14 are dep~cted to illustrate the ver~atillty of the present invention. Preferably, the capaciti~s of the input and circulation means 30 are manufactured to be less than about five gallons of ink or printing fluido Other combinations of ink input systems and dampening systems can be visuali7ed by tho~e skilled in the art based on the teachings of this disclosure, with~ut departing from its general intent.
As also shown in FIG. 14 an auxiliary transfer xoller 213 can be utllized in rotational contact with the inking drum 11. The auxiliary trans~er roller 213 transfers printing fluid to an auxiliary inking drum 211.
further auxiliary form roller 216 is in rota~ion~l contact with the auxiliary inking drum 211 ~nd the plate ~.92~J7 cylinder 15. Other variations of auxiliary rollers, drums and cylinder~ are p~ssible for use with the present invention.
During pract~ce oP the keyless inking technology disclosed in U.S. Pat~nt ~,690,0~5, it became apparent that should the need arise to ln~tall page-wide instead o~ press-wlde keyless inking ~ytems, this ~epar~tely-driven pan roller prior art would be particularly difficult to engineer. The central pages of a four wide newspaper press would re~uire mounting and coupling the central two pan rollers to a separate drive ~ystem ~ithin the restrict~on of about only 3/4" margin between ~ide-by-side page locations of a typical newspaper web.
In pra~ticing the teachings of U.S. Patent 4,690,055 with newspaper presses four pages wide, one is compelled to manufacture a heavy, relatively large-diametered pan roller to avoid deflection or deformation in the unsupported central region. Doing so requires, in turn, a large size ink pan and reservoir assembly, which together with ~ssorted pumps and hoses occupies considerable space just under the printing ¢ouple.
Further, a minimum practical ink fluid level in the pan reservoir results in a relatively large working lnX
volume of 5 to 10 gal. This is an inconveniently large volume of ink to handle whenever an ink change is required~

' 2 ~ ~92 '~7 It was also determ~ned, in practicing the ~echnology of U.S. Patent 4,69~,055, that normal amounts of pan roller to metering roller contact pressure, corresp~nding to, for instance rom 1/8" to 3/16" flat portion at the nip formed by ~he two rollers, can result in foreshor~ened ~eterin~ roller l~fet~mes due to premature wear of the metering roller surface coating6. Depending upon the severity of the general print~ng conditions, the metering roller technologies of UuS. Patent Numbers 4,537,127; 4,567,827, and 4,601,242 may ~eter ink effectively for only 5 to 20 million printed copies instead of the expscted 40 million copies or more, based upon doctor blade wear testing in the absence of a low-moving pan roller in contact with the ~etering roller.
These and other reasons motivated the present invention leading to the present improved keyless inking system, which ~ystem retains all o~ the functional features necessary to practice trouble free lithographic keyless inking previously taught by U.S. Patent 4,690,055.
FIG. 18a represents ~n general the prior art roller configuxation technology o~ U.S. Patent 4,690,055. FIG.
18b is ~imilar but with pan roller 21 placed out o~
contact with the metering roller 20. FIGS. 18c, 18d and 18e represent similar keyless press roller configurations without a pan roller but with an added rider roller 29 2~L~9277 in contact with meterin~ xoller 20. FIG. 18e, however, represents a press #ystem having a second transfer roller 17 according to the present invention.
All elements 10, 12, 15, 16 and 11 remained identical in the FIGS. 18a-18e configurations while these systems were evaluated for runnability and printability~ All o~ them conveyed ink reasonably well to the paper substrate being printed. However~ ~onfigurations uslng only one transfer roller 13 and no pan roller 21, namely the configurations of FIGS. 18c and 18d, resulted in measurably inferior uniformity of cross-press optical density values when running a critical format such as that shown in FIG. 20.
This similarly-poor result was obtained using the configuration of FIG. 18b corresponding to the technology disclosed in U.~. Patent 4,690,055 excepting with a purposeful gap between the pan roller 21 and the metering roller 20. U.S. Patent 4j690,055 teaches that interference between the pan and metering rollers is preferred. The above disclosed result seems to verify this teaching. The instant result also verifies that a frictionally-driven press-speed rider roller 29 in place of the pr~or ~rt slow-speed pan roller, when riding ayainst the metering roller, Figures 18c and 18d, does not emulate the prior art performance quality. Certain of these results are included for re~erence in the Table depicted in FIG. 19.

, ~. , ,, . ' ,~

;

2 ~ 7 ~

When a frictionally driven roller 17 as in FIG. 18e was ~nstalled in contact with both the main inking drum 11 and the metering roller 20 and whe~l using the 6ame non-uniform format of ~IG. 20, the printing ~ystem closely approxi~ated the advantageous attributes of the prior art pan roller inker ~s tauyht by U.S. Patent 4,690,055. Tha corresponding r~sults ~re also listed in the Table of FIG. 19.
The frictionally driven, press speed, second transfer roller of the present ~nvention avoids~ the necessi~y ~or pressure indented contact of thè metering roller with any inking roller operating at significantly different surface speed than the metering roller ~tself.
We h~ve found the useful lifeti~es of the previously-disclosed, advantageous, hard, oleophilic, hydrophobic ink metering rollers may thereby be increased two-~old to ten-fold over that when the 6eparately-driven pan roller technology of U.S. Patent 4,690,055 ~s employed.
Reasons for the advantageous, more uniform optical density effec~ are not clearly known. Cerkainly, i~ the additional differently-diametered roller 17 merely functioned to exchange and rearrange the ink in the cells of the ink metering roller 20, it ~hould be expacted that the FIG. 18c and 18d variations would function similarly to the FIG. 18e configuration. The Table of FIG. 19 verifies this is not the case and the dual-contact, two-- ~ .... ,;; ,.~.. .. . . .

2~9~7~

transfer roller configuration depicted in FIG. .~8e is clearly superior.
Indep@ndent of the exact technical reasons, the present invention hows that a ~low-moving ~nk-input pan-roller r;ding agains~ the press~peed celled metering roller of the prior ar~ i~ not ~he only conf~uration that provides the process functions necessary to assure minimum format dependence of optical density when printing with a keyless lithographic printing press. The slow-moving pan roller can be replaced by a second, press-speed transer roller as herein disclo~ed and thereby obtain fully equivalant printed guality, while providing the new advantages of less circulating volume of printiny fluid, smaller overall inker dimensions, less wear of the ~elled metering roller during printing operations and the opportunity to use any of several printing fluid input devices.
The invention is not limited to the particular details of the apparatus depicted and other modificat~ons and applications are contemplated. Certain other changes may be made in the above described apparatus without departing from the true ~pirit and ~cope of the invention herein involved. It i8 lntended, therefore, that the subject matter in the above depiction chall be interpreted as illustrative and not in a limiting sen~e.

,.................. ~

Claims (20)

1. In a keyless lithographic printing press having blanket cylinder and plate cylinder with printing plate mounted thereon, an improved keyless printing system, comprising:
means for supplying dampening water to the plate cylinder;
at least one form roller in rotational contact with the plate cylinder;
inking drum in rotational contact with said form roller;
at least first and second transfer rollers in rotational contact with said inking drum;
metering roller having at least an oleophilic and hydrophobic surface which is capable of retaining a quantity of printing fluid, said metering roller in rotational contact with aid first and second transfer rollers; and means for supplying printing fluid to said metering roller.

2. The improved keyless printing system according to claim 1, wherein said first and second transfer rollers are frictionally driven by at least said metering roller.

3. The improved keyless printing system according to claim 1, wherein, when said metering roller rotates during a printing operation, said first and second transfer rollers rotate and have a surface velocity substantially the same as the surface velocity of said metering roller.

4. The improved keyless printing system according to claim 1, wherein said means for supplying dampening water to the plate cylinder has at least a dampening roller in rotational contact with said plate cylinder.

5. The improved keyless printing system according to claim 1, wherein said means for supplying dampening water to the plate cylinder has at least a dampening roller in rotational contact with said inking drum, said inking drum thereby transferring said dampening water from said dampening roller to said plate cylinder via said form roller.

6. The improved keyless printing system according to claim 1, wherein said means for supplying printing fluid is an undershot fountain system which imparts printing fluid to said metering roller.

7. The improved keyless printing system according to claim 1, wherein said means for supplying printing fluid is an injector system which inputs printing fluid to said metering roller.

8. The improved keyless printing system according to claim 1, wherein said means for supplying printing fluid a slit-manifold system which inputs printing fluid to said metering roller.

9. The improved keyless printing system according to claim 1, wherein said means for supplying printing fluid 15 a pressurized printing fluid and circulation system for providing printing fluid to said metering roller.

10. In a keyless lithographic printing press having at least an inking drum and a metering roller having at least an oleophilic and hydrophobic surface capable of retaining a quantity of printing fluid, an improved keyless printing fluid conveying means, comprising:
a plurality of transfer rollers in rotational contact with said inking drum and said metering roller, said transfer rollers conveying at least said printing fluid from said metering roller to said inking drum during operation of the printing press.

11. The improved keyless printing system according to claim 10, wherein said printing fluid conveying means comprises first and second transfer rollers.

12. The improved keyless printing system according to claim 10, wherein said plurality of transfer rollers are frictionally driven by at least said metering roller.

13. The improved keyless printing system according to claim 10, wherein, when said metering roller rotates during a printing operation, said plurality of transfer rollers rotate and have a surface velocity substantially the same as the surface velocity of said metering roller.

14. In a keyless lithographic printing press having blanket cylinder and plate cylinder with printing plate mounted thereon, an improved keyless printing system, comprising:
means for supplying dampening water to the plate cylinder;
at least one form roller in rotational contact with the plate cylinder;
inking drum in rotational contact with said form roller;
at least first and second transfer rollers in rotational contact with said inking drum;

metering roller having at least an oleophilic and hydrophobic surface which is capable of retaining a quantity of printing fluid, said metering roller in rotational contact with said first and second transfer rollers;
means for supplying printing fluid to said metering roller; and said first and second transfer rollers being driven by at least said metering roller and having a surface velocity substantially the same as the surface velocity of said metering roller.

15. The improved keyless printing system according to claim 14, wherein said means for supplying dampening water to the plate cylinder has at least a dampening roller in rotational contact with said plate cylinder.

16. The improved keyless printing system according to claim 14, wherein said means for supplying dampening water to the plate cylinder has at least a dampening roller in rotational contact with said inking drum, said inking drum thereby transferring said dampening water from said dampening roller to said plate cylinder via said form roller.

17. The improved keyless printing system according to a 14, wherein said means for supplying printing fluid is an undershot fountain system which imparts printing fluid to said metering roller.

18. The improved keyless printing system according to claim 14, wherein said means for supplying printing fluid is and injector system which inputs printing fluid to said metering roller.

19. The improved keyless printing system according to claim 14, wherein said means for supplying printing fluid is a slit-manifold system which inputs printing fluid to said metering roller.

20. The improved keyless printing system according to claim 14, wherein said means for supplying printing fluid is a pressurized printing fluid and circulation system for providing printing fluid to said metering roller.