CA1127453A - Ink metering apparatus - Google Patents

Abstract

HAROLD P. DAHLGREN
INK METERING APPARATUS
ABSTRACT

Ink metering apparatus comprising a resilient surfaced roller urged into pressure indented relation with a printing plate; a source of ink positioned to apply an excess of ink to the surface of the roller which has applied ink to the printing plate; and a resilient metering member having a hard, smooth, polished, highly developed, flexible edge resiliently urged in a direction generally radial of the roller and rigidly supported in a direction generally tangent to the roller surface for forming a film of controlled thickness on the surface of the resilient roller. The flexible polished edge on the metering member is positioned in pressure relation with the resilient roller surface such that ink carried by the resilient roller surface impinges against a metering surface on the metering member adjacent the polished edge. The flexible polished edge is resiliently urged into pressure indented relation with the resilient roller surface by a force of sufficient magni-tude to deform the flexible polished edge and the resilient roller surface such that the edge and the roller surface complement each other and cooperate to form an orifice which is self-adjusting to imperfections of the metering member and the resilient roller surface. The metering surface on the metering member, against which ink impinges, is oriented such that hydrokinetic forces exerted by the ink on the metering member do not significantly alter the ink film when the surface speed of the resilient roller surface is changed. The metering member is positioned such that the angle of departure between the metering member and the surface of the roller which has passed the polished edge is sufficient to cause separation of the ink from the metering member to prevent trailing of ink along the surface of the metering member.

Description

i3 1 BACKGROUND OF THE I~VENTION
Inkers for printing plates which have achieved commer~
cial accept2nce generally comprise from two to four form rollers which are positioned in rolling engagement with a printing plate.
Each o~ the form rollers is usually in rolling engagement with one or more vibrator rollers to which ink is applied by a multi-tude of rollers in a train of rollers of varying diameters arran-~ed in pyramid fashion. Ink is delivered to the train of rollers over a ductor roller which oscillates into and out of engagement 10 with a film of ink formed by a flexible doctor blade urged into 1, engagement with the hard surface of an ink fountain roller by a multiplicity of ink keys.
The ink film formed on the ink fountain roller has been too thick and too irregular for applicat;on directly to a print~
ing plate for quality printing. These inkers which include a multiplicity of rollers are intended to reduce the thickness of the ink film and to deliver a film of uni orm thickness to the printing plate. However~ since the ink film on each form roller is not totally replenished on each revolution of the form roller;
image ghosting and ink accumulation and starvation is not elim-inated, Thè multiple roller inkers require complex drive trains and are relatively expensive to purchase initially and to main~
tain thereafter.
In an attempt to eliminate both the expense and the disadvantages of multiple roller inkers, many recent attempts have ~een made to develop inkers wherein a fresh film of ink is metered onto a form roller which ls urged into pressure relation with a printing plate to eliminate the train of rollers, to eliminate image ghosting, and to eliminate ink accumulation of starvation ~k -~12-~53 1 United States Patent No. 3,283,712 describes an inkiny system devised ~o overcome ghosting The system comprises two rollers of substantially equal diameter urged together in pressure indented relation to form a nip, surfaces of the rollers adjacent the nip moving in opposite directions. One of the rollers was cleaned by a pair of doctor blades and the rollers were urged together such that the local pressure at any point selected along the contact generatrix or nip was greater -than a "critical pres-sure threshold," such that, theoretically, one of the rollers carried a film of ink of constant thickness throughout the length of the roller to be applied directly to a printing plate without being contacted by equalizer rollers.
The theory of operation set forth in the aforementioned patent failed to take into consideration the fact that viscosity, surface tension, cohesion of ink molecules, and adhesion of ink molecules to molecules on surfaces oE the rollers are all related to temperature of the ink, Thus~ since adjacent surfaces of the rollers at the nip moved in opposite directions and since pressure was not uniform along the length o the nip, temperature generated .
b~ adjacent surfaces moving in opposite directions would result in a substantial variation in temperature along the length of the rollers and of ~nk carried b~ the rollers~
In addition to the irregular temperature distribution across the length of the rollers, inkers built in accordance with teachings of the aforementioned patent required substantial power for rotating the rollers and adjustment of the thickness of a film of ink metered through the nip was very sensitive because slight changes in surface speed of the roller which had been completed cleaned of ink resulted in drastic changes in the fllm of ink carried b~ the other roller,

-2~

1 It was also observed that the surface of the resilient roller tended to vibrate or chat-ter as it moved through the nip and encountered substan-tial forces as a result of being in pres-sure indented relation with the surface of the other roller mov-ing in the opposite direction which resulted in printing streaks which extended transversely of the direc-tion of travel of the sheet through the printing press. Experience has revealed that conventional viscous ink could not be used in this inking system.
It appears that the inker disclosed in the a~oremention-ed patent has failed to achieve commercial success because ~f itsinability to meter a film of uniform thickness suitable for ink-ing a printing plate and because of excessive power requirements for driving the rollers when adjacent surfaces move in opposite directions and when heavily striped together.
Ideally, a stationary metering unit requiring no dri~e in addition to that required for rotating a single form roller would appear to be a solution to the problems presented by previous inkers. Attempts have been made to employ doctor ~lades as ink metering units, but these attempts have uniYersally met with fail-ure. Doctor blades are successfully used as ink wiping units in inkers having a train of rollers for distributing and smoothing the ink, but such blades have not proven suitable for use as the sole ink metering unit for a resiliently surfaced form roller Printing ink is generally an oily viscous substance which is highly pigmented and formulated to be sticky or tacky so that the ink will properly adhere to image areas of the printing plate. When the image area of the printing plate trans-fers ink directly to paper or to a blanket cylinder ~hich in turn transfers ink to paper~ small paper fibers, lint and frag-ments of coating material may adhere to the surface of the plate 1 cylinder. The plate causes the foreiyn substance -to be applied to the surEace of the ink applicator roller. If -the sur~ace of the ink applicator roller is moved directly into the reservoir and then ~iped or scraped by a conven~ional doctor blade, the foreign substance tends to collect at the edge of the doctor blade which results in formation of an irregular film of ink on -the surface of the roller. For this reason, in addition to the er-ratic behavior of the surface of the resilient roller under dynam-ic conditions, no inking device has been devised heretofore which is capable of supporting a doctor blade for metering a uniform film of ink directly onto the surface of a resilient roller in rolling engagement with a printing plate.
United States Patent No. 3,298,305 discloses an inking mechanism having a stationary, rigidly supported edge held in a position to significantly indent a resilient roller surface such that a fil~ forming portion on the inking mechanism would form a thin uniform film of ink which was delivered through a slot in the inking mechanism and applied to the roller surface. The edge was described as being positively locked in position to prevent any lifting by the ink film on the roller so as not to detrimentally affect the hydrodynamic effect.
I have obser~ed that uniform pressure cannot be obtained between the rigidly posi~ioned edge and the surface of a resil-ient roller under dynamic conditions because the apparent modulus of elasticity of the resilient surface on the roller incrèases as the rate of cyclic loading increases. The dimensions of the re-silient form roller also vary under dynamic conditions~ if the resil~ent surface is subjected to cyclic loading, since resilient màterials have a memory and do not immediately recover to an original dimension after bein~ compressed. Further~ vibration in 1 the resilient roller surface is induced by sutstantial indentation of the surface since the resilient cover is stacked up as a re-sult of compressive loading on one side of the stationary rigid edge and is under tension on the other side of ~he edge. Vibra-tion in the axis of the roller relati~e to a stationary rigid edge which results from movement of the surface of the roller into and out of the gap in the plate cylinder is not readily iso-lated from a rigidl~ supported edge.
It is further noted that a mechanism as described in lO Patent No 3,298,305, which wipes the ink with a rigidly supported edge does not efficiently and effectively form a thin uniform film Furthermore, a rigid mechanism does not readil~ or easily yield to conform to surface variations of the roller and, there-fore, yields a non-uniform ink film in ranges of desirable thick-nesses United States Patent No. 4,0Q7,682 discloses a method of inking a resilient surfaced form roller wherein an ultra-thin doctor blade is mounted at a reverse angle to the ink to split the ink and apply the ink to the roller in the desired thickness ~O when relative motion is provided between the roller and the doctor blade. The doctor blade is described as being flexible, for ex-ample~ a ~lade construc-ted of Swedish steel having a thickness of ~ aQ8 inches in one example and a t~ickness of Q.015 inches in another example.
The disclosure of Patent N~. 4,007,682 states that when an ink of high viscosity is used and the rate of rel~tive motion between the roller surface and the edge of the blade is high~ a sharp ~lade will "float" along on the ink surface, but the lead edge of the doctor blade should be cylindrical having a radius of curvature equal to one-half the thickness of the blade when less 1 viscous inks are used. ~he disclosure s-tates that the velocity of the roller surface relative to the doc-tor blade is adjusted to interact with the ink viscosity, blade geometry and downwarcl force on the blade to cause the ink to be carried into the nip between the blade and the roller surface whereby its viscous resistance to shear forces creates an upward pressure causing the doctor blade to "float" o~er the ink film it produces, The surface speed of the roller is varied for varying the thickness of the film of ink formed thereon. The disclosure states that rotation of the inking roller at 68 inches per second provides a uniform eoating of ink 5 microns -th~c~ and that when the rotation speed of the inking roller is increased to 172 inches per second a layer of ink 12 microns thick is formed I have observed that a wedge~shaped entrance surface on an ultra-thin flexible doctor blade lightly urged toward a roller surfaee as deseribed in Pa-tent No. 4,007,682, causes the flexible blade to hydroplane such that the ink film thickness ehanges with press speed resulting in color density variation on printed sheets It has further been noted that a s~gnificant radius on the edge of the blade forms an area in ~hich small paper fibers and lint, eommonly referred to as hickeys, collec-t which results in formation of an irregular film of ink on the surface of the roller~
Further~ it appears that the cylindrical end of the doetor ~lade disclosed in Patent No. 4,007,682 is not shaped to defleet the roller surface away from the lower surface of the doctor ~lade and~ therefore, ink carried by the surface of the roller will trail the lower surface of the doctor blade causing an aceumulation of ink on the surface of the doctor blade which will result in dripping and destruction of the uniformity of the .

1 ink film forme~ by the blade.
The invention described herein addresses the problem of forming a film of printing ink oE uniform thickness on a resil-ient roller surface and moving the film o~ ink into engagement with the image area on a printing plate while eliminating trains of rollers in inking systems, elimin~ting the necessity for con-sumption of excessive power for metering a thin unifoxm ink film, eliminating problems attendant to collection of "hicke~s", pro-viding a metering member which does not detrimentally stress a resilient roller surface so as to impart vibration to the resil-ient roller surface, and providing a metering member which forms a uniform film the thicknss of which is independent of press speed, SUMMARY OF INVENTION
The improved inker which is the subject o~ this appli-cation comprises a resilient surfaced roller adapted to be urged into pressure indented relation with a printing plate, in combin-ation with an improved li~uid metering apparatus adap-ted to form a thin uniform film of ink on the surface of the resilient roller, the thickness of the film of ink being independent of the surface speed o~ the resilient roller~
The surface of the roller moving from engagement with the printing plate is moved through a reserYOir of ink such that an excess of ink is applied to the surface of the roller. A
meterin~ member is positioned in relation to the resilient sur-face o~ the roller to form an or~fice through which a thin uni-form film of ink is extruded which adheres to the resilient sur-f~ce o~ the roller.
The metering member is resiliently mounted such that a polished flexi~le edge thereon moves relative to the axis of the resilient covered roller and is urged toward the resilient surface ... ... __. . . . . , .. . . . . . . .... ~ . . ..

i3 1 of the roller to maintain a substantially constan-t pressure relationship relat.i.ve to the roller surface along the entire len~th of the roller and circumferentially thereabout.
The polished fle~ible edge of the metering member is rigidly supporied in a direc-tion ~enerally tangen-t ~o the roller surface and is shaped and oriented to deform the resilien-t roller surface to minimize wetting of a substantial surface area of the metering member downstream from the polished edge to cause sep-aration of ink from the metering member adjacent the polished edge. The lower surface ofthe metering member is shaped and/or positioned such that ink on the indented resilient roller sur-face does not separate from the roller surface and attach itself to the lower surface of the metering member when rebounding from a compressed position occupied as a result of passing the flex-ible polished edge of the metering member, Flow of ink in the reservoir toward the metering member is turbulent due to the structure of the metering mem~er adjacent the reservoir, thus causing lint and other foreign matter to gen-erall~ be rejected from an area of high pressure immediately ad-jacent the leading edge of the metering member, This lint andforeign matter is retained in the reservoir and therefore lodging of particles against the edge o~ the metering member is also minimized,. Flow of ink carried by movement of the surface of the resilient roller toward the polished edge of the metering member experiences a rap~d increase in pressureand flow becomes laminar immediately adjacent the polished edge~ Velocit~ of the ink in creases as it moves through an orifice between the resilient sur-face of the roller and the polished edge of the metering member, Immediatel~do~nstream from the ori~ice, the ink separates from the polished surface and is retained on the resilient surface of the roller~

1 The pollshed edge oE the meterlng member is urged to-ward the resilient surface of -the applicator roller by a static force in a range between about one and six pounds per linear inch of ~he length of the edge, the force being sufficient to indent the roller surface along the entire length o~ the roller sur~ace and being dependent upon the modulus of elasticity of the resilient roller, the cover thickness, the ~iscosity of the ink and other characteristics of the ink. The polished edge of the metering member slightly indents the surface of the resilient roller, for example about 0.03 inches on a 40 Shore A durometer roller having a cover thickness of approximately 5/16 inches. ~s the roller rotates, the polished edge of the metering member moves relative to the axis of the roller to maintain a condition of equilibrium such that the edge forms an orifice which automatically moves radially relative to the axis of the roller to form a film of uniform thickness longitudinally of the roller surface and circum-ferentially thereabout although the roller surface is not perfect-ly round and not free of slight waviness~
A primary object of the invention is to pro~ide an ink-ing system for printing presses affording continuous precisioncontrol of the thickness of an ink film delivered to a printing plate to eliminate ghosting and resultant varlation in color of pr~nted images, Another object of the invention is to provide an improved liquid metering member and support means associated therewith to position the metering memberrelatiYe to a resilient roller sur-face for forming a liquid film on the roller surface~ the thick-ness of the film being substantially independent of the speed of the roller sur~ace.
Another object of the invention is to provide an improYed illk metering member particularly adapted to be urged into relation 5~

1 with a roller such tha-t ~orei~n matter in ink movi.ng toward the surface of the metering member and carried by the sur~ace of the roller is diverted away from -the metering member.
A further objec-t of the invention is to pxovide a simple and efficient inking system capable of forming a thin continuous film of ink of uniform thickness longi-tudinally and circumferent-ially of a moving resilient xoller surface~ the system being stationary to operate without generating excessive heat and with-out expending excessive energy for driving the system9 Another object of the invention is to provide an im-proved method and apparatus for forming a uniform filrn of ink on the surface of a resilient roller wherein the ink is ~etered through an orifice defined between a flexible polished edge re siliently urged toward the resilient roller surface so that the orifice automatically moves radially of said roller such that the thickness of the film of ink is independent of the surface speed of the roller and does not substantially vary as the speed of the printing press is changed.
A still further object of the invention is to provide ~n improved method and apparatus for forming a uniform film of ink on the surface of a resilient roller b~ use o~ an edge mounted on a cantilever, the edge being moved into pressure relationship with an ink fil~ on the roller surface past a threshold point where the ~.nk film ceases to decrease in thickness when an in-cre`ase in force is applied to the edge and ~egins to increase in thickness while becoming more nearly uniform~
Another object of the invention is to pro~ide an inking.
system wherein a non-rotating metering member is positioned and adapted such that ink passing under the member upon being metered does not separate from itself and accumulate on the lower surface --10~

1 of the metering member to ultimately be pulled again to the metered film to destroy uniformit~.
Another object oE -the invention is to provide an im-proved inking system in which a polished edge on a metering mem-ber is resiliently urged in-to pressure indented relation with a resilient roller surface such that vibration in the printing press is isolated from the polished edge to eliminate streaks in the ink film formed by the inking system.
Another object is to provide an inking system in which a polished edge on a metering surface is urged into pressure in-dented relation with a resilient roller surface such that the angle of the metering surface relative to a radius of the roller is adjustable to adjust the thickness of a film carried by the roller surface past the polished edged.
Other and further objects will become apparent upon re-ferring to the following detailed description and to the attached drawings, DESCRIPTION OF DRA~INGS
Drawings of a preferred embodiment of the invention are 2~ annexed hereto so that the inven~ion may be better and more ~fully understood, in which:
Figure 1 is a cross-sectional view taken transversely through a printing press;
Figure 2 is an enlarged fragmentary cross~sectional view illustrating the relationship of the metering member rela-tive to a resilient covered roller;
- Figure 3 is an enlarged diagrammatic illustration of a first embodiment of the metering member and a portion of the re-silient surface of the applicator roller underdyn~mic conditions;

3~ Figure 4 is an enlarged diagrammatic view of a second embodiment of the metering member;

J ~l2.7~ii3 1 Figure 5 is a diagrammatic illustration showing that as force urging the metering member into pressure indented relation with a roller surface is increased a minimum ink film thickness is reached;
Figure 6 is a diag.rammatic view similar to Figure 5 illustrating a family of curves;
Figure 7 is a diagrammatic illustration showing varia-tiOIl in color density laterally across a printed sheet in response to changes in force urging an edge of the metering member into pressure relation with a resilient surface;
Figure 8 is a diagrammatic illustration showing varia-tion in position of an edge on the meterin~ member as a resilient covered roller rotates at a constant speed and also at changing speeds;
Figure 9 is a diagrammatic illustration that ink film thickness is independent of press speed; and Figure 10 is a dîagram~atic illustration showing the color density on a printed sheet, Numeral references are employed to designate like parts ~0 throughout the various figures of the drawing.
DESCRIPTION OF A PREFERRED EMBODIMENT
. . . _ , . . _ _ Referring to Figures 1 and 2 of the drawing~ the numeral 1 generall~ designates an inker having spaced side frames 2 mov-ably secured to side frames 3 of a printing press haviny a--con-ventional plate cylinder P~ blacket cylinder B, and impression cylinder I mounted therein for printing on a web ~ or a sheet of paper.
Support means 5 is provided to adjustably secure meter-ing member 10 between side frames 2 and to position metering mem--ber 10 in relation to a resilient covered applicator roller 40 ~l'Z,~
1 Opposite ends oE applicator roller 40 are rotatably secured to side frames 2 in suitable bearings and applicator roller ~0 is driven by any suitable drive means such as a chain 4 drivingly connecting a sprocket on the plate cylinder to the sprocket on a clutch (not shown) at an end of applicator roller 40. The surface speed of applicator roller 40 is pre~erably equal to the surface speed of plate cylinder P. Elowever, the surface speed of appli-cator roller 40 can be about ten percent faster or slower than the surface speed of plate cylinder P to facilitate cleaning non-image areas of the plate P~
End dams 6 are secured to support means 5 and are urgedinto sealing relation with opposite ends of applic~tor roller 40 and member 10 forming a reservoir R from which ink is metered on-to the surface of applicator roller 40. One or more vibrator rollers 8 are positioned in rollingengagement ~lith ink on the sur-face of applicator roller 40 for smoothing any surface irregular-ities which may appear in the ink film before the ink film is carried by the surface of roller 40 to the surface of a printing plate P' on plate cylinder P. Vibrator rollers 8 are in rolling enga~ement with ink on the surface of applicator roller 40 and not only smooth surface irregularities, but also change a slick metered finish to smooth matt-like finish for conditioning the ink film for proper printing to an image on a printing cylinder.
It will be appreciated that as the surface of applicator roller 40 moves away from the surface of printing plate P~ the surface is submerged in ink and an excess of ink is applied there-to at the reservoir R.
If the inking system is employed for lithographic print-ing wherein dampening fluid is applied to the surface of the printing plate P' on plate cylinder P, means are provided for i3 1 evaporating dampening Eluid from the surface of roller 40 to pre-vent accumulation of excessive dampening f].uid in reservoir R.
As illustrated in Figure 1 of the drawing, a hollow per~orated tube 9 extends transversely between side ~rames 2 and has aper-tures formed therein through which dried compressed aîr is deliv-ered for causing a stream of dry air to be directed toward the surface of roller 40. An end of tube 9 is connected by a hose to an air compressor ~not shownl.
Also, when dampening ~luid is used with -the inker of the present invention, a greater than normal proportion of alcohol to water may be employed to speed evaporation of the dampening fluid which remains on the applicator roller as it moves away from the printing plate. In fact, the dampening solution could con~
tain more than the normal 5-25% alcohol to insure rapid evapora tion of the dampening solution from the applicator roller during travel between the plate and the ink metering member~
As will be hereinafter more fully expl~ined~ to provide precision control of the viscosity of ink in reserYoir R and to vary the viscosity of the ink in reservoir ~, flexible tubes 7 2Q are connected to deliver fluid, such as water of controlled temp- t erature and at a controlled flow rate~ into one end of passage 5' in support member 5 and out of the other end of passage 5'.
For high speed we~ printing~ the physical properties of ink film 130 formed between metering member 10 and resilient cover 44 of roller 40 may be controlled ~y temperature control of a fluid passing through vibrators 8 and through the passage in the core 42 of roll 40, It has been found that a high flow rate produces only a small temperature change along the length o a roller and that by monitoring and controlling the output tempera-ture, heat can be dissipated and ink temperature controlled such 7~5~

1 that the physical properties of the generated film are held sub-stantially constant throughout the length of a production run, Therefore, by cooling and/or heating fluid passing through member 5 and roller core 42, the ink viscosity at the shear nip is controlled to maintain a constant desirable ink film for proper printing to plate P.
INK METEP~ING MEMBER
Two embodiments of ink metering member 10 are illust-rated in Figures 3 and 4 of the drawing.
1~ Referring particularly to Figure 3, the ink metering member, generally designated by the numeral 10, has a smooth., polished highly developed, precision edge 15 which is formed at the juncture of surfaces 12 and 18.
Edge 15 preferably extends in length for a distance within a range of from 10 to 100 inches, and i5 defined by polish-ed portions 14 and 16 on the surfaces 12 and 18, Polished portions 14 and 16 meet to form a wedge having an edge be`vel angle "a"
of approximately 90 degrees. Although a 90 degree angle between the portions 14 and 16 has been found to be very effectiYe for forming the precision edge 15, the edge may also be formed with the polished portion at other angles of less than 120 degrees and greater than 60 degrees.
The edge 15 is formed on relatively hard material, and normally metal is used. The material preferably has a hardness in a range between Rockwell C10 and Rockwell C60, and preferably about Rockwell CS0~
~ etering member 10 is preferably a resilient me-tallic matexial having a modulus of elasticity in a range between 15 and 30 x 106 psi, and preferably about 29 x 106 psi.

Metering member 10 has been formed with good results from a strip of stainless steel of the type employed in the 5~

1 construction of compressor valves which is com~ercially available from Uddeholm and dis-tribute~ as U~IB s-tainless 716. The stain-lesssteel s-trip had a thickness of 0.031 inches and a width of 3. 5 inches The strip of material had a bright extra fine polish-ed surface ~inish, deburred edges, extra accurate flatness and normal straightness. Since the strip of stainless steel material was hardened and tempered, it was resis-tant -to corrosion in the presence of air, water and most organic acids in dilute form at room temperature.
The strip of stainless steel was selected for its hard-ness, flatness, resilience and fine surface finish to provide high wear resistance and good fatigue properties~
Prior to polishing, the edge 15 at the juncture of sur-faces 12 and 18 defined a line consisting of ragged notches forming a ragged edge contour. To form a precision straigh~ edge to define an unbroken l~ne across the extent of metering member 10, several segments of the strip material t~ere clamped together and surfaces 12 thereof were simultaneously ground, then honed with a ~ine-grit stone as a first step in forming polished edge ~0 15.
A pair of strips from which metering ~embers 10 were to be formed were then clamped in a vice with a spacer between the strips, surfaces 12 on each of the strips being positioned in a common plane so as to support a sanding block, Surfaces 12 on each of the strips were sequentially smoothed ~ith sandpaper having grit sizes 32Q, 40Q and 60Q and then polished with crocus cloth.
As a third step~ the pair of stainless steel strips were positioned on a flat horizontal surface such that each surface 12 was adjacent the other surface 12, the surface 19 on each strip ~16~
.~

~Z.~53 1 being supported on a spacer such that edge 12 was inclined at an angle of about 0.2 degrees from a vertical line. Portion 16 of each surface 18 was sequen-tially smoothed with sandpaper having grit sizes 320, 400 and 600 and -then polished with crocus cloth.
If a feather edge forms on the metering mem~er while portions 14 and 16 of surfaces 12 and 18 are being sanded and polished, the feather should be removed, When the ~eather, or wire-like irregular edge is removed, a microscopic curve is formed on the edge Thus, in the process of polishing or "sharpening"

the edge 15, the acuteness of the edge should ~e altered somewhat to form a non-cutting, non-film-piercing edge~ This process pro-duces a fine, continuous, smooth, straight, polished, highly developed edge 15 having m~nimal surface irregularities. There should be no small notches or protrusions in the edge. The de-veloped edge 15 formed by polished portions 14 and 16 of surfaces 12 and 18 is a very fine edge which has been polished to bring it to a highly developed finish, and as nearly perfect condition as possi~le.
Edge 15 is finished to a surface finish appro~imating that of the edge of a razor blade~ However, it will be apprec-iated that the angle a bet~een polished portions 14 and 16 of surfaces 12 and 18 is significantly greater than the bevel angle a' on a razor and thus a blunt, non-cutting and non-piercing edge is formed. Actually~ surface 14 blends into surface 16 through edge 15 to form a continu~us polished surface adjacent edge 15~
The material used to form the edge 15 must not only be hard and capable of being formed to provide a blunt, ~ine, polish-ed~ unbroken edge, but the material must also be ~le~ble along the length of the edge 15 In fact, the edge 15 must ~ quite 1 flexible in a lengthwise direction so that when urged in-to pres-sure indented rela-tion with the resilient sur~ace of applicator roller 40 the edge 15 will be flexed, yielding to the influence of the surface of roller ~0, to conform the edge 15 and the surface of roller 40 to form ~ uniform indented area along the length of roller 40. As will be hereinafter more ~ully explained, the surface of roller 40 has a thickness o~ approximately 0.25 inches and a resilience of about 40 SHORE A durometer. This flexure of edge 15 to obtain conformation with the surface of roller 40 should be possible without excessively indenting the surface of the roller when in a static condition.
The edge 15 on metering member 10 should be ~ounted so that it is resiliently urged toward the surface of the applicator roller 40 and is free for movement in a direction radial to the applicator roller. Also~ the edge 15 must be rigidly supported in a direction substant~ally tangent to the applicator roller surface.
The ideal support for the edge 15 is a flexible canti-lever beam which supports the edge 15 and provides the required bias and rigidity, Although the edge 15 may ~e a part of a sep-arate element which is attached to a cantilever beam~ it is pre-ferable to form the edge 15 on the beam so that the t~o are an integral unit, To accomplish this, the beam must be constructed of a material of the type necessar~ ~or the ed~e 15 and must be flexible in two directions; namely, along the length ~f the edge and also along the ~idth oE the strip or the leng-th of the canti-lever beam.
The ink metering member illustrated in ~igure 3 of the drawing, wherein the edge 15 is formed on the unsupported end of the~cantilever beam, has a substantially rectangular cross section 1 bounded by surfaces 11, 12, 1~ and 19~ Surfacf-~ 12 lies in a plane 12' which intersects a plane 18' in which surEace 18 lies when the can-tilever beam is in a non-flexed condition. Planes 12' and 18' intersect at an apex "A" which is a straight line.
As an example, the cantilever beam which includes the edge 15 may be formed from a thin, flexible, elongated stainless steel strip, as hereinbefore described, having a thickness of 0.031 inches and a width of 3.5 inches. The width of the beam, or the length of the strip of material, will preferably be within the range of from 10 to 100 inches, and the beam is supported to be flexible along the length of edge 15 as well as along tAe length of the cantilever beam. The modulus of elasticit~ E of the beam may be, for example 29 x 106 psi, which represents the stiffness of the material; that is, its resistance to deformation.
When combined with the moment of inertia I, the EI factor repre-sents the stiffness of the cantilever beam~
The specific dimensions and characteristics of the metering memher 10 are presented by way of explanation, and such dimensions, characteristics and mounting may vary to meet specific conditions, Consequently, preferable ranges have been provided herein, A second embodiment~ generally designated by the numeral 10', is illustrated in Figure 4 of the drawing.
The ink metering member 10' will finally have a fine, polished highly developed precision edge 25 which is formed at the juncture of polished surfaces 24 and 26 using the method hereinbefore described for forming edge 15 on member lQ, Metering member 10l differs from metering member 10 primarily in that a groove Qr relieved area 27 is formed in the lower surface 28 of the strip of material from which metering member 10' is formed.

~19--~Z~53 1 The strip o~ material from which metering member 10' is formed is preferably stainless or high carbon steel having a thickness of about 0.050 inches and width of abou-t 3.5 inches, The portion of the strip of material which will be pol-ished to form polished e~ge 25 is masked and the metallic mater-ial adjacent thereto is removed by chemically milliny to remove a portion of the metal without relieving or creating stress that would cause the strip of material to warp, Surfaces 28a bounding the support area are smoothed by grinding to remove approximately 0,003 inch of rough surface material. Surfaces bounding the relieved area 27 may then be electropolished to provide a very smooth surface finish. These surfaces may be electropolished by making the member 10~ the anode and submerging it in electrGlyte containing phosphoric acid and butyl alcohol so that the high points on the surfaces will be dissolved in the electrolyte.
If the thickness~ the distance between surfaces 28 and 29~ of the strip of material is 0,Q50 inches, the depth of the relieved area 2~ is preferably about a, 020 inches such that the th~ckness of the materàal between surface 28' and surface 29 is approximately 0.030 inches~
Surface 28a intersects the polished surf~ce 2& at an angle A~ in a range between 30 and 90 degrees as shown.
The upper portion of surface 24 of meter~ng mem~er 10' is bevelled at an an~le of approximately 3Q degrees to form sur-face 22, In the illustxated embodiment of metering mem~er lQ', polished surface 24 extends upwardly from polished edge 25 a dis-tance approximately equal to the depth of relieved area 27~ or approximately Q.02Q inches to intersect surface 22, It should be 1~L2.~3 1 readily apparent ~h~t polished ~urfaces 26 supports -the polished ed~e 25. If surfaces 24 and 28a are parallel, surEace 26 can be refinished without chan~ing the load bearing charac-teristics of the polished edge portion 25 of ~he meterin~ member 10'.
However, it should be readily apparent -that surface 22 may be formed to extend through pol~shed edge 25, if i-t is deemed expedient to do so, such that the polished portion 24 and surface 22 would lie in a common plane.
The relief angle A' should be sufficient to cause an ink film carried by the surface of roller 40 to depart and sep-arate from surface 26 without accumulating either on surface 26 or 28a to cause ultimate dripping of the accumulated ink to cause non-uniformity.
PPLICATOR ROLLER
The applicator roller 40 comprises a hollow~ rigid, tubular, metallic core 42 having a resilient non-absorbent co~er 44 secured thereto, the cover having a uniformly smooth and re-silient outer surface 45. The cover 44 on applicator ~oller 40, while being resilient~ is relatively firm, for example in a range between 30 and 90 Shore A durometer, The cover 44 on applicator roller 40 is pxeferably formed of a resilient urethane, polyurethane or rubber~like mater-ial attached to a metallic core ~2.
The cover 44 on applicator roller 40 should have high tensile stren~th~ excellent tear and abrasion resistance, and resistance to oils, solvents and chemicalsq The cover should, furthermore, have low compression set, good recovery/ and uniform ink recept~y~ty, A suitable cover can be formed .using a resin commercially ayailable under the registered trademark "Solithane"
available from Thiokol Chemical Corporation of Trenton~ New Jersey,in comhination with suitable plasticizers to form a -21~

7~5~

1 resilient cover of about 40 Shore A durometer.
After a resilient cover 44 has been formed, the roller may have a slick glazed outer skin or film over the surface thereof which is remo~ed by grinding. ~fter grinding, the plas-tic surface is sanded by using 180 grit sandpaper to ~orm a surface of uniform roughness over the surface 45 of the resilient cover 44. Microscopic reservoirs into which ink is attached, assure that a continuous film of ink is maintained on the surface 45 o~
applicator roller 40, Final finishing using various sandpapers to 400 grit is done to insure a velvet smooth surface free of "orange peel" or other surface irregularities. As will be here--inafter more fully explained, adhesive ~orce between molecules of ink and molecules of the sur~ace 45 of cover 44 must exceed co-hesive force between ink molecules to permit shearing the ink to form a controlled film of ink on the surface 45 of applicator roller 40.
It will be appreciated that it is physically i~practical, if not impossible, to construct roller 40 such that surface 45 is perfectly round in a circumferential direction~ perfectly straight in a lon~itudinal direction/ and prec~sely concentric to the axis of core 42~ The straightness of surface 45 on roller 4Q can be economically held within a tolerance of about 0,002 inches along the length of roller 40 and the radial eccentricity can be econ-omically held within a tolerance of about O.OQ15 inches~
A Shore A durometer test is generally used to indicate the hardness of a resilient roller co~er by measuring resistance to penetration at a constant temperature o~ a~out 76 degrees F
while the resilient cover is stationary The apparent hardness of a resilient surface under dynamic conditions deviates radical-ly from the hardness indicated ~y t~e durometer test under static ~22-1 conditions. The spring constant o~ a resilient material ~lso in-creases slightly as deforma~ion increases.
As the frequency of loading of a resilient member in-creases, the dyna~ic modulus or apparent modulus of elasticity increases causing the cover to appear as a harder, stiffer mater-ial. However, cyclic loading of a resilient member results in generation of internal heat, with the increase in temperature resulting in a decrease in the durometer and therefore the modulus of elas-ticity of the resilient cover.
tO Further, since the surface 45 of cover 44 on roller 40 is preferably in pressure indented relation with the surface of a plate cylinder, the plate cylinder having a gap extending longi-tudinally thereof, this cyclic loading will result in generation of heat at an irregular rate circumferentially of the surface 45, Such temperature differences over surface 45 may cause an appreciable variation in the radical distance from the axis of the roller 40 to points over the surface 45, because the coeffic-ient of thermal expansion of elastomer~c materials employed for forming resilient roller covers is seyeral times the coefficient ~O of thermal expansion of steel.
As shown, roller 40 can ~e diEferent in diameter than ~he plate cylinder P without adversely affecting metering of the film 130 since metering member 10 produces a continuous ri~bon of ink regardless of ~he prior impression and regardless of thermal changes within the roller cover 44, SUP~ORT STRUCTURE
Referring to Figure 1 of the drawing~ suppoxt ~eans 5 for supporting metering member 10 in cantilever fashion comprises an elongated rigid support bar 50 having a ground and true flat face 52 on one side thereof and a surEace 54 angularly disposed 1 relative to flat face 52 forming a shoulcler 55 which extends longitudinally of support bar S0. Journals 56 extend outwardly from opposite ends of support bar 50 and are rotatably secured in self-aligning bushing 57 :in bearing blocks 60 having outwardly extending projections 58 adjacent opposite sides thereof.
Each of the projections 58 has an elongated slot formed therein through which anchor bolts 52 extend for securing bearing blocks 60 to inker side frame 2.
Four elevating screws 64 extend through threaded pass-ages in projections 58 on bearing blocks 60 and engage surface 65 on inker side frame 2 for movement of support ~ar 50 in a vertical direction, as illustrated in ~igure l, Lateral adjustment screws 66 extend through threaded apertures in outward extending lugs 68 on inker side frame 2 and engage end surface 66' on projections 58, From the foregoing it should be readily apparent tha~
the position of bearing block 60 is adjustable vertically and horizontally, as viewed in Figure l of the drawing~ ~or movement of support bar 50 relative to the axis C of roller 40~
An arm 70 is bolted or otherwise secured to the end of journal 56 on support bar 50 and is urged by a pistion rod 71 of fluid pressure actuated cylinder 72 into engagement with an end o~ a stop screw 74 threadedly secured to an arm 75 ~olted or otherw~se secured to bear1ng block 60, It should be readily apparent that support bar 50 is rotatable relatiye to bearing block 60 by adjustment o~ the position of the end of stop screw 74 relative to arm 75.
Pressure regulator R' is installed i.n orde~ to set inlet pressure in cylinder 72 sufficient to hold arm 70 firmly against 30 scre~ 74 for all indentations of edge 15 into surface 45 of cover 44, i3 1 ~letering member 10 is secured to the flat surface 52 on support bar by bolts 76 extending throu~h spaced apertures in clamp member 78, through oversized spaced apertures extending through the cantilever beam adjacent the rear edge 11 thereof, Bolts 76 are threadedly secured in threaded passages formed in support bar 50. solts 76 and clamp 78 cooperate such that the metering member 10 is uniformly attached or supported by support bar 50 such that the edge 15 has a uniform spring rate along its lenght.
In the embodiment of the ~pparatus illustrated in Figure 1, stop screw 74 is remotely controlled by a direct cur-rent electrically driven motor 80 secured to arm 75 by a support bracket 81. If it is deemed expedient to do so, a gear reducer may be positioned between motor 80 and screw 74 to further con-trol the speed of rotation of screw 74, A splined coupling 76 is connected ~etween screw 74 and the output shaft of motor 80.
Motor 80 is commerc~ally available from Globe Industrials Division of TRW, Inc,, of D~yton, Ohio.
Conductors 82 and 84 extend between motor 80 and motor position control unit 85, Motor position control unit 85 is of conventional design and comprises a direct current source and a three position switch, Motor pos-ition control unit 85 has a digital readout indicator 86 associated therewith to indicate the position o a rotary potentiometer (not shown~ at the end of stop screw 74 which engages arm 7Q to provide visual indication of the pOSiti of the support 50 for metering member 10 or metering member 10'.
~iotQr position control unit 85 is secured to the side frame 3 of the printing press in the embodiment illustrated in Figure 1 of the drawing, However, an additional motor position control unit 85 ~s preferably positioned adjacent the deliYery end of the ~25-s~

1 printing press so that the position of metering member 10 can be adjusted remotely as printed sheets are inspected to adjust color density of ink as required.
Inker side frames 2 are pivo-tally secured by a shaft ~0 to press side frames 3 adjacent opposite sides of the printing press. A fluid pressure actuated throw-off cylinder 92 is piv otally secured to lugs 93 secured to side frames 3 of the print-ing press and has a piston rod 94 pivotally secured to lug 95 welded or otherwise secured to inker side frames 2~ An on-stop adjustment screw 96 is threadedly secured to a lug secured to the press side frame 3 and is positioned to engage inker side ' frame 2 when pressure between the surface 45 of applicator roller 42 and printing plate P' has been properlv established. An off-stop adjustment screw 98 is threadedly secured to a lug welded or otherwise secured to ~rinting press side frame 3 to engage inker side frame 2 when the piston rod 94 in throw-off cylinder 92 is extended to thereby separate surface 45 on applicator roller 40 from the surface of printing plate P', As hereinbefore described, end dams 6 are urged into sealing relation with opposite ends of applicator roller 40 and define opposite ends of reservoir R. An ink retainer member 100 is positioned in sealing relation with the surface 45 of appli-cator roller 40, as illustrated in Figure 1 and 2 of the dra~ing, and has opposite ends secured to end dams 6. The lower edge 102 of ink retainer member 100 is preferably spaced slightly from surface 12 on ink metering member lar for example ,Q25 inches, Ink retainer member 100 defines the entrance side of reservoir R, The exit side of reser~oir R is defined by member 105 secured to support bar 50 by bolts 106. Thelower seal 108 ad-jacent member lG5 is positioned adjacent the upper surface lq 1 of metering member 10 to prevent flow of ink f~om reservoir R
onto the upper surface 19 of metering member 10 to form an area of stagnation in which ink ceases to flow. Since ink is thixo-tropic, the viscosity o~ ink is significantly reduced when the ink is in motion as compared to the viscosity of ink which is not in motion.
As illustrated in Figure 1 of the drawing~ an ink agit-ator 110 is secured to ink retainer member 100 for agitating ink in reservoir ~.
Ink agitator 110 is of conventional design and is com-mercially available for Baldwin-Gegenheimer of Stamford, Connecticut.
The ink agitator 110 generally comprises a rack and pinion which extends longitudinally across the upper portion of the reservoir R and carries a mixing head driven by a chain which is driven by a constant speed motor, -As the mixing head appro-aches an end dam 6 adjacent one end of applicato~-roller 40, it reverses direction and moves to the other end of the reservoir.
The agitator rotates within the ink to laterally stir, or shear ink to prevent irregularities in viscosity along said reservoir.
OPERATION
The operation and function of the appara-tus herein before descri~ed is as follo~s:
Metering member 10 is aligned and attached to the face 52 of supportbar 50 by bolts 76. Anchor bolts 52 are loosened to permit movement of bearing block 60 relative to in~er side frame 2.
Lateral adjustment screws 66 are emplo~ed ~or moving bearing block 6a relative to applicator roller 40 for alignment of edge 15 on metering member 10 relative to surface 45 on resil-ient cover 44 of applicator roller 40 ~f~ 3 1 Elevating screws 6~ are employed for adjus-ting the angular relationship between surface 12 on me~ering roller 10 relative to a radius of applicator roller 40.
After edge 15 on metering member 10 has been aligned with the surface of applicator roller 40 and the angular relation-ship between surface 12 and a line extendin~ radially of appli-cator roller 40 has been established, anchor bolts 52 are tight-ened, rigidly securing bearing blocks 60 relative to side frames 2, Edge 15 is now position in "kiss" contact with the surface 1~ ~5 on applicator roller 40. An amount of ink in excess of that needed to ink the plate P' on the plate cylinder P is provided from the reservoir R to the surface o~ the applicator roller which is approaching metering surface 12 on metering member 10, After edge 15 has been moved into "kiss" contact with the surface 45, stop screw 74 is rotated thereby rotating support bar 50 from the position illustrated in full outline in Figure 2 of the drawing to the pos~tion illustrated in dashed outline.
This results in deflection of the cantilever beam and the fle~ible polished edge 15 is urged into pressure ind`ented relation to conform with the resilient surface of applicator roller 4a. Rotation or roller 40 now moyes ink from reservoir into contact with edge 15 and metering surface 12 thus shearing ink of finite thickness on the surface 45 to a film ~30 which may be altered in thickness as will be hereinafter more fully explained~
Assuming that edge 15 is mounted on a cantileYer beam rigidly supported at one end, the equaticn of the elastic curve is Y = F(.2L3 - 3L2 x + x3~ - 6EI, In the prototype, a distance between should 55 and meter-ing surface 12 on metering member 10, which would be the unsupported 31'~Lf~,'7~5~

1 end the cantilever beam, was 1.625 inches, the distance between surfaces 18 and 19 was 0.031 inches and a static load of four pounds per inch of width was applied at the edge 15. The modulus of elasticity E of the metering member 10 was 27 x 10~ psi.
The amount of inertia I of a rectangular area is equal to bh3 - 12, where b is equal to the width of the base of the rectangular area and h is equal to the height of the rectangular area. The amount of inertia I of metering member 10 having a thickness of 0.031 inches was calculated to be 2,4 x 10 6 per inch of width of the cantilever beam.
At the unsupported end of the cantilever ~eam! x is equal to O, and therefore, the deflection Y is equal to FL - 3 EI
Therefore, it was calculated that the deflection of the unsupport-ed end of the cantilever beam should be approximately 0,Og8 inches when a load of four pounds per inch o~ width is applied to the edge 15. Therefore~ it was concluded that the spring constant for the cantilever beam would be 0.022 inches of deflection per pound of force applied to the edge 15 or ~5 pounds per inch of the w~dth of edge 15, It is, of course, appreciated that the equation of the elastic curve set forth above is only approximate for calculating the deflection of the edge 15 since metering member 10 is not rigidl~ supported or clamped at the shoulder 55 on support bar 50, Ho~ever~ it ~ill be readily apparent that edge 15 is resiliently urged in a direction rad~ally of applicator roller 40, The deflection or the distance moved by the edge 15 on metering memker 10, in the above example, was measured to be 0 20 inches whRn an average static force of four pounds per inch was applied to edge 15, Dividin~ the force of four pounds per inch by the deflection of metering member 10 reveals tha-t the spring 1 constant of meterin~ member 10 is low and approximately 20 pounds per inch of deflection. The spring constant calculated from the actual deflection of resilient member 10 differs from the approx-imate spring constant calcula-ted abo~e. However, the differences in the spring constant is approximately calculated and as actually measured was predicted As will be hereinafter more fully explained, the com-bined distance that the edge 15 is deflected plus the distance that edge 15 is indented into the roller surface should be sub-stantially greater than the maximum space between points on roller surface 45 and edge 15 when the surface and the edge are ur~ed into kiss contact. For example, irregularities or manu-facturin~ imperfections tn roller surface 45 and sli~ht waviness of edge 15 might result in a maximum deviation of 0.002 inches error such that the surface 45 and edge 15 do not conform when first touched together, If edge 15 is deflected 0,20 inches and indènted into surface 45 a distance 0.03a inches, the initial deviation of 0,00~ would be about 1% of the combined distance of 0,23 inches. Since edge 15 and cover 44 are resilient~ the edge and the surface will flex and conform to each other, ~hen thus con~ormed, pressure along the strip area will be substantially constant and the affect o small differences will be insignif-icant, The combined distance of deflection and indentation is preferably more than ten times the initial de~iation, such that the maximum error after the ed~e 15 and surface 45 are ur~ed in-to pressure indented relation will be less than ten percent, to maint~in an ink film thickness which will print what is consider-ed ~y printers as acceptable uniformity of color density, ~ow ever, for wilat is referred to as "very tight" control~ color ~Z~3 1 density should not vary more -than five percent over the sur~ace o~ a sheet.
As illustrate~ in Figure 3 o~ the drawi.n~, the edye 15 on metering member 10 is urged into pressure indented relation with the surface of applicator roller 40 such that the resilient material is stacked up, up-stream from surface 12 Eorming a bulge or wave 120 in the co~er 44 while a groove or channel 125 is ~ormed in the cover downstream from edge 15. This forms an orifice through which ink is extruded; the orifice being bounded on one side by a portion of surface 12 and edge 15 and bounded on the other side by a portion of the surface 45, proba~ly between the crest of the bulge 120 and the portion of the surface 45 immediately adjacent polished edge 15~ As the cantilever beam permits the fl.exible edge 15 to follow the contour of the appli-cator roller, the orifice automatically moyes radially relative to the axis C of the applicator roller 40~ Since the orifice is formed by the cooperation of the opposing flexibly biased edge 15 and resilient surface 45 of the applicator rollerl this move~ent is desirable if a constant pressure relationship is to be main-tained on the ink extruded through the orifice. The surface ofthe applicator roller 4 a will constantly change in contour as the roller rotates due to elastic memory, temperature changes~
and variations.~n the dyna~ic modulus of elastIcity~ as herein-before discussed. Consequently~ it is important that the edge 15 automatically move radially and flex length~ise to follow this changing contour, It should be noted that ink carried by the surface 45 of applicator roller 4Q impinges against metering surface 12 creating a reg~Qn of tubulent flow adjacent the cres-t of the bulge 120 in the resilient roller surface, Thus, although edge 15 is resiliently ur~ed downwardly as viewed in Figure 3, meter ing surface 12 is shaped and positioned to prevent lift.ing of edge 15 by hydrodynamic forces exerted on metering member 10 by the ink. This condition is established by positioning polished edge 15 such that it is closer to the central axis C of appli-cator roller 40 than any other point of metering member 10. The blunt polished edge 15 favorably deforms the resilient coYer 44 on applicator roller 40 to form a metering orifice for forming a film of ink of precisely controlled thickness.
Surface 18 on metering member 10, immediately down-stream from polished edge 15 is positioned so that the metered film of ink is in contact with metering member 10 only at edge 15 to cause the ink film 130 to immediately separata from meter-ing member 10 to prevent trailing o~ the ink along surface 18 which would result ~n ~ccumulation ofink, dxipping, and conse~
quently~ erratic flow which would destroy the uniformity of film In the embodiment of ~etering member 10 illustrated in Figure 4Of the drawing~ the lower surface of metering member ~0 10' has been formed such that surface 28a at the heel of polished surface 26 andbounding relieved area 27 is angularl~ disposed relative to the direction of movement of ink.film 130 such that roller suxface 44 cannot rebound to a position wherein ink film 130 contacts surface 28'~
Thus in the embodiment of the invention illustrated in Figure 3 of the drawing as well as in the embodiment illustrated in Figure 4 of the drawing~ the metering member is shaped or pQsitioned to cause ink ~ilm 13Q to ~mmediately separate from the meteri.ng mem~er pxior to the. surface of the meterin~ member returning to its relaxed, non-indented r position~

5~

1 During testinc3 of the apparatus hereinbefore described, it was discovered that as force urying edge 15 into pressure indented relation with surface 45 is initially increased, the thickness of film 130 is decreased to a minimum thickness; and then, with a further increase in force, -the film 130 begins to increase in thickness.
Referrin~ to ~igure 5 of the drawing~ it will be noted that this surprising phenomenon occurs as force urging edge 15 on the cantilever beam metering member 10 toward the surface of roller 40 is increased. When a light force per linear inch of the length of edge 15 was employed for urging edge 15 into pres-sure relation with surface 45, color density decreased as load was applied and was uniform circumferentially of the surface 45 on roller 40. However, with this light loading, color density was not uniform laterally across the length of roller 40. As the force was increased~ the ink film thIckness on the roller was reduced until a somewhat heavier load per inch of the width ~f edge 15 ~as reached. Ink film thickness then began to in-crease as force urging polished edge 15 toward the central axis C of roller 40 was increased. Otherwise stated~.as force was increased~ the film thickness first was reduced and then ~egan to increase as further load was appl~ed. However~ color density beca~e ext~emely uniform laterall~ across the length of roller

4~ when the load approched a static average force of four pounds per inch on the edge 15.
This phenomenon, where at a threshold pressure, the ink film thickness suddenly ceases to decrease and ~egins to increase as force on the edge 15 becomes higher has been observed when the edge 15 constitutes the lower forward edge of a cant~-lever beam metering member Figures 3 and 4 sho~ metering mem~er . -33-~lZ,~53 igures 3 and 4 show meterin~ member 10 and 10' respect-ively in such indented relation with surface 45 of roller 40 at a position such that edge deflecting load, pressure and inden-tation and therefore, ink film thickness (which determines color) is substantially constant.
Referring to Figure 5, it should be observed that the thickness o~ ink film 130 varies as a function of the indentation of polished edge 15 into resilient surface 44 of applicator roller As described above, as the indentation increases, the thick-ness of ink film 130 decreases rapidly to a minimum and then begins increasing. Irregularities or imperfections in surfaces on metering member 10 and application roller 40 are easily seen in the metered ink film 130 until positioned edge 15 is indented to a point where the variation in edge deflection along the length of edge 15 is small~ as related to the total deflection, for example, less than ten percent At this point, the ink film be comes more regular and uniform and remains substantially uniform as polished ed~e 15 is further deflected and indented into the surface of applicator roller 40.
It has been obser~ed that the thickness of the minimum ink film~ as depicted at the bottom of the curve in Figure 5, is controlled by the angle o~ metering surface 12 relati~e to the radius of roller 40 Referring to Figure 3 of the drawing~ when metering surface 12 is pivoted about the polished edge 15 from the illus-trated position~ wherein metering surface 12 leans toward the crest of bulge 120~ in a clockwise direction as viewed in Figure 3, to a position wherein metering surface 12 passes a line ex-tending radially of the roller, the minimum ~ilm thickness in-dicated in Figure 5 is changed. Thus b~ adjusting the angle :9 ~2~ 3 1 between metering surface 12 and a radius of the roller, a family of curves as illustrated in Figure 5 will be generated as illus-trated in Fi~ure 6.
From the foregoing it should be readily apparent that the thickness of ink film 130 can be adjusted by rotating meter-ing surface 12 about polished edge 15 or by increasing indentation of polished edge 15 into the resilient surface 44 of applicator roller 40.
It has also ~een observed that the thickness of film 0 13à can be changed by varying viscosity of ink in reservoir R, Thus by adjusting the temperature of water or other suitable liquid through tubes 7 and passage 5' in support bar 50, the vis-cosity of ink in reservoir R can be adjusted.
It should be noted that the minimum film thickness obtainable, as a result of adjusting the angular relationship be-tween metering surface 12 and a radius of roller 40 may result in completely removing ink from the surface of roller 40 prior to the point at which the film thickness begins to increase, Thus, to prevent damage to the surface of roller 40, the ink film thickness should be o~served wh.ile adjustments are be~ng made, When film 130 becomes very thin, applicator roller 40 shouLd be stopped while force urging polished edge 15 into pressure indented relatiQn with the roller ~s increased. After the force has been increased sufficiently to pass through the minimum fi.lm thickness threshold, the roller can be rotated without fear of lose of lubrlcating qualities of film 1307 Figure 7 diagrammatically illustrates the phenomenon hereinbefore discussed wh~ch results in incxeasing unifo~mity of color density of ink on a printed sheet as the force resiliently urging edge 15 into pressure indented relation with the surface 45 on roller 4Q is increased, . -35-~'Z,~LS3 1 As hereinbefore descri~ed in the remarks relatiny to Figure 10 of the drawing, color density of ink printed on a sheet was measure~ at points over -the surEace of the sheet. Maximum and minimum color density readings were recorded. Sheets were selected which were printed with different loads applied to the edge 15 on the metering member 10.
It will be noted tha~ the variation in color density between the maximum and minimum on a sheet decreased as force ur~in~ polished edge 15 into pressure indented relation with the resilient cover ~4 on roller 40 was increased, as indicated by the length of lines Dl, D2, D3 and D4 in Figure 7.
It will be appreciated that when force urging edge 15 into pressure indented relation with the surface 45 was increased, metering member 10 being a cantile~er beam was deflected; the resilient cover 44 on roller 40 was deflected or indented; and edge 15 was defo~med slightly along the length thereof such that the edge 15 and the surface 45 of roller 40 immediatel~ adjacent thereto were con~ormed~ even though edge 15 and the surface of the roller when positioned in kiss contact did no-t perfectly con-~0 fo~-m. Thus, deflection of metering member 10~ deflection of edge 15 along the length thereof, and indentation of cover 44 all con~
tribute to attaining the proper ink film thickness and uniformity of color density over the surface of a printed sheet Referring to Figures 5 and 7 of the dra~ing, it will be noted that the ink f~lm thickness decreases to a minimum and then begins to increase as force urging edge 15 into pressure indented relation with roller surface 45 is increased~ Thus~ the same ink film thickness is achieved at two different points on the curve. ~owever, as ind-cated by the difference in the l~ngths ~f lines D2 and D4 in Figure 7 of the drawing, variation in color density is different at the two points on the curve.

3 ~ ,53 1 Referring to Fi~ure 8 of the drawing, a dial indicator was attached to support bar 50 and positioned in engagement with the,upper sur~ace 19 adjacent me-tering surface 12 on metering member 10. ~s applicator roller 40 was ro-tated, a to-tal dial indicator reading of 0.0006 inches was obser~ed~ This indicated that the runout in the radius of the surface of roller 40 was 0.0003 inches and that edge 15 on metering member 10 moYed 0.0006 inches upon each revolution of roller 40. ~s the surface speed of roller 40 was increased, the magnitude of movement of edge 15 remained substantially the same at different surface speeds of roller 40. However, the total deflection of me-tering member 10 increased somewhat as the surface speed of roller 40 increased.
Thus, the polished edge 15 on metering member 10 automatically moves relative to the axis C of applicator roller 4Q upon each revolution of applicator roller 40 and in response to changes in.
speed of applicator roller 40.
' Referring to Figure 9 of the drawingl it will be noted that ink film thickness remained substantially constant over a broad speed range and therefore is substantially independent of ,20 the surface speed of applicator roller ~0.
As hereinbefore described~ the 'edge 15.on metering me~er 10 automatically moves radially as applicator roller rotates. HoweYer~ metering member 10 is positioned such that metering surface 12 and polished edge 15 are rigidly supported in a tangential direction, It will be noted that force im-parted to metering surface 12 as a result of ink impinging there~
aga~nst, is directed substantially tangentially o~ applicator roller 40 and that metering member 10 is angularly positioned such that it is ~ery stiff in a direction generally tangential.
to applicator roller 40.' 1 While is is necessary tha-t metering member 10 be pos-itioned to resiliently urge edge 15 in a ra~ial direction, meter-ing member 10 must be of sufficient thickness to permit formation of metering surface 12 and polished ed~e 15 thereon. Metering mem~er 10 should not be too thin because, when compressive force is exerted in a plane of a thin plate, it will tend to buckle and distort in much the same manner as a long, thin, axiall~
loaded column.
The color density of ink printed onto a s~eet was measured using a "SOS-40" digital reflection densitometer, com-mercially available for CONSAR Corporation of Garland~ Texas.
The color density readings of process yellow longitudinally and transversely of the printed sheet are indicated in Figure 10 of the drawing It will be noted that lateral color control is within a "very tight" range and that longitudinal control is also "very tight". Other process colors; namely magenta~ cyan and black were measured with equally good color control The data diagrammatically illustrated in F;gure lQ of the drawing indicates that a uniform film is being metered by metering member 10 onto the surface 45 of applicator roller 40.
It has ~een observed that power required for driving a printing press having the inking system hereinbefore described mounted thereon is not significantly different from power re-quired for driving printing presses equipped with conventional inkers. However, as hereinbefore explained~ the ghoshed image on the surface of applicator roller 40 which is moving from plate P' toward the entrance side of reservoir R is completel~ erased and a fresh film of ink is metered and offered to printing plate P' upon each revolution of applicator roller 40 Thus~ ghos-ting has heen eliminated, Further, the metering member lQ and la' ~1%~ 3 1 constructed and supported as hereinbefore described is capable of metering a film which is sufficiently thin and sufficiently uniform for inking a printing plate to provide very high quality multi-color printing. Color density can be changed immediately by merely adjustin~ the position of stop s~rew 74~ which is re-motely controlled~
The metering edge 15 on metering member 10~ when pro-perly formed, causes lint and other foreign matter in the ink to be rejected from the orifice formed between metering member 10 and the surface of applicator roller 40. To accomplish this function, the lead or metering surface 12 toward which the roller surface 45 is moving plays an important roll, Metering surface 12 forms a barrier above the ed~e 15 against which the excess ink on the applicator roller 40 impinges, creating an area of turbulence as hereinbefore described. Since the area of high pressure is formed immediately prior to movement of the ink past polished edge 15, lint and foreign matter will tend to ~e rejected from this area if a low pressure p~th is provided in the reser-voir, Reservoir R is preferably at atmospheric pressure~

It has been observed that so long as metering surface 12 is maintained in a position within about 30 degrees either side of a radius of roller 40 which passes through polished edge 15~ lint and foreign matter is not significantly collected ad-jacent polished edge 15. However, the tendenc~ for fore~gn matter to collect adjacent edge 15 ~ncreases as metering surface 22 l~S moved in a direction toward the crest of bulge 120~ Thus~
metering surface 12 is also maintained at an angle to maintain an area of tur~ulence in the reserYoir adjacent thereto. It is further noted that creation Gf abrupt surface 12 substantially rad~,al pre~ents formation of hydrokinetic or hydrodynamic forces 7~53 1 which would create a hyclraulic pressure wedge which would tend to lift polished edge 15 and thereby cause the thickness of ink film 130 to be changed as the surface speed of roller 40 changes.
Thus, edge 15 is hydrosta-tically supported by ink carried by roller surface 45.
From the foregoing, it should be readily apparent that ink metering member 10 and ink metering member 10' when associated with applicator roller 40 accomplish the objects of the invention hereinbefore enumerated.
It should further be appreciated that other and further em~odiments of the invention may be devised without departing from the basic concept thereof, ~20

Claims (19)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Liquid metering apparatus comprising a roller having a resilient outer surface and means operative, upon rotation of the roller, for forming, from a liquid film of irregular thick-ness carried by the roller, a thin liquid film of uniform thick-ness, said means comprising a metering member pressed substantially radially inwards of the roller characterised in that said metering member has a metering edge and a trailing edge and presents, to the irregular liquid film, a substantially flat metering surface on the metering member adjacent the metering edge, and is pressed so that both the metering edge and the trailing edge are indented into the resilient roller surface.

2. Apparatus as claimed in claim 1 wherein the metering edge is indented into the roller surface by a distance which is equal to or greater than the distance by which the trailing edge is so indented.

3. Apparatus as claimed in claim 1 characterised in that the metering edge is provided by the intersection between the metering surface and a support surface which confronts the resilient outer surface of the roller, and the trailing edge is provided by the intersection between the support surface and a further surface of the metering member.

4. Apparatus as claimed in claim 1 characterised in that the metering member is carried by support means which permits adjustment of the angular relationship of the metering member relative to the roller, thereby to vary the relative amounts by which the metering edge and trailing edge are indented into the roller.

5. Apparatus as claimed in claim 4 characterised in that the support means includes adjustment means permitting adjustment of the extent of indentation of the metering member into the outer surface of the roller.

6. Apparatus as claimed in claim 1 characterised in that the metering surface lies in a plane which intersects at an angle of less than 30°, a plane which is radially disposed relative to the roller and passes through the metering edge.

7. Apparatus as claimed in claim 1 characterised in that the metering member is flexible.

8. Apparatus as claimed in claim 3, 4 or 5 characterised in that the metering member is in the form of a strip having a front surface which constitutes the metering surface and, spaced away from the front surface, a recess of which a surface close to the front surface constitutes the said further surface of the metering member.

9. Apparatus as claimed in claim 1 wherein the roller is an ink-applying roller in a printing machine and the liquid is printing ink.

10. Apparatus as claimed in claim 9 wherein the ink-applying roller applies ink directly to a printing plate.

11. A method of metering liquid in liquid metering apparatus, which comprises supplying the liquid as a film of irregular thickness to the outer surface of a roller, which outer surface is resilient, rotating said roller, and pressing a metering member substantially radially inwards of said roller so that a metering edge and a trailing edge of said metering member are indented in to said resilient outer surface of the roller, and

Claim 11 continued......

a substantially flat metering surface adjacent said metering edge is presented to the liquid film of irregular thickness.

12. A method as claimed in claim 11 wherein the metering member is pressed towards the said resilient surface so that metering edge is indented therein by an amount equal to or to a greater extent than the trailing edge.

13. A method as claimed in claim 11 characterised in that the pressure between said metering member and the roller surface is increased relative to the pressure at which a given or desired thickness of liquid film is first obtained.

14. A method as claimed in claim 13, characterised in that the pressure between said metering member and said roller surface is further increased when the given or desired thickness of the liquid film is obtained until the thickness of said film has passed a minimum value and has obtained again the given or wanted thickness.

15. A method as claimed in claim 11 characterised in that the viscosity of the liquid carried on the roller surface is controlled.

16. A method as claimed in claim 15 characterised in that the viscosity is controlled by temperature control.

17. A method as claimed in claim 13 ox 14 characterised in that the temperature of the liquid is controlled.

18. A method as claimed in claim 11 wherein the roller is an ink-applying roller in a printing machine and the liquid is ink.

19. A method as claimed in claim 18 wherein the ink-applying roller applies ink directly to a printing plate.