EP0070484A1 - Vorrichtung zum Dosieren von Tinte mit einem abgestumpften Dosierelement - Google Patents

Vorrichtung zum Dosieren von Tinte mit einem abgestumpften Dosierelement Download PDF

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Publication number
EP0070484A1
EP0070484A1 EP82106199A EP82106199A EP0070484A1 EP 0070484 A1 EP0070484 A1 EP 0070484A1 EP 82106199 A EP82106199 A EP 82106199A EP 82106199 A EP82106199 A EP 82106199A EP 0070484 A1 EP0070484 A1 EP 0070484A1
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EP
European Patent Office
Prior art keywords
metering
roller
ink
edge
metering member
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP82106199A
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English (en)
French (fr)
Inventor
Harold Phillip Dahlgren
John W. Gardiner
James E. Taylor
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Dahlgren Manufacturing Co Inc
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Dahlgren Manufacturing Co Inc
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Filing date
Publication date
Application filed by Dahlgren Manufacturing Co Inc filed Critical Dahlgren Manufacturing Co Inc
Publication of EP0070484A1 publication Critical patent/EP0070484A1/de
Withdrawn legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41F—PRINTING MACHINES OR PRESSES
    • B41F31/00—Inking arrangements or devices
    • B41F31/02—Ducts, containers, supply or metering devices
    • B41F31/04—Ducts, containers, supply or metering devices with duct-blades or like metering devices

Definitions

  • I nkers for printing plates which have achieved commercial acceptance generally comprise from two to four form rollers which are positioned in rolling engagement with a printing plate.
  • Each of the form rollers is usually in rolling engagement with one or more vibrator rollers to which ink is applied by a multitude of rollers in a train of rollers of varying diameters arranged in pyramid fashion.
  • Ink is delivered to the train of rollers over a ductor roller, which oscillates into and out of engagement with'an irregular film of ink.
  • the irregular film is formed by a flexible doctor blade urged into engagement with a hard surface on a slowly rotating ink fountain roller, by a multiplicity of ink keys.
  • the ink film formed on the ink fountain roller is too thick and too irregular for application directly to a printing plate for quality printing.
  • These inkers which include a multiplicity of rollers are intended to reduce the thickness of the ink and to constantly deliver a film of a uniform controllable thickness to the printing plate.
  • image ghosting and ink accumulation and starvation is ever present.
  • One 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 is completely cleaned by a pair of doctor blades and the rollers are urged together such that the local pressure at any point selected along the contact generatrix or nip is greater than a "critical pressure threshold," such that, theoretically, one of the rollers carries a film of ink of constant thickness, throughout the length of the rollers, to be applied directly to a printing plate without being contacted by equalizer rollers.
  • a stationary metering unit requiring no drive 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 blades as ink metering units, but these attempts have universally met with failure.
  • 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 in a lithographic printing application.
  • 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 a lithographic printing plate.
  • image area of the printing plate transfers ink directly to paper or to a blanket cylinder which in turn transfers ink to paper, small paper fibers, lint and fragments of coating material may adhere to the surface of the plate cylinder.
  • the plate causes the foreign substance to be applied to the surface of the ink applicator roller. If the surface of the ink applicator roller is moved directly into the reservoir and then wiped or scraped by a conventional 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.
  • Uniform pressure cannot be maintained between a rigidly positioned edge and the surface of a resilient roller under dynamic conditions because the apparent modulus of elasticity of the resilient surface on the roller increases as the rate of cyclic loading increases.
  • the dimensions of the resilient form roller vary under dynamic conditions, if the resilient surface is subjected to cyclic loading, since resilient materials have a memory and do not immediately recover to an original dimension after being compressed. Further, vibration and fatigue failure in the resilient roller surface is induced by substantial indentation of the surface since the resilient cover is stacked up as a result of compressive loading on one side of the stationary rigid edge and is under tension on the other side of the edge. Vibration in the axis of the roller relative 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 isolated from a rigidly supported edge.
  • the invention described herein addresses the problem of continuously forming a film of printing ink of uniform thickness on a resilient roller surface and moving the film of ink into engagement with the image area on a lithographic printing plate while eliminating trains of rollers in inking systems, eliminating the necessity for consumption of excessive power for metering a thin uniform ink film, eliminating problems attendant to collection of "hickeys", providing a metering member which does not detrimentally stress a resilient roller surface so as to impart vibration to the resilient roller surface, and providing a metering apparatus which forms a uniform film, the thickness of which is independent of press speed.
  • the inker disclosed herein relates to improvements in an inker of the type disclosed in U. S. Serial No. 142,596, filed April 22, 1980, the disclosure of which is incorporated herein in its entirety for all purposes.
  • the improved inker which is the subject of this application comprises a single resilient surfaced applicator roller adapted to be urged into pressure indented relation with a lithographic printing plate, in combination with an improved ink metering member adapted to form a thin controllable and uniform film of printing ink on the surface of the form roller, the thickness of the film of printing ink being independent of the surface speed of the resilient roller.
  • a metering member having a metering surface arrangement for a particular ink viscosity, is positioned in relation to the resilient surface of the roller to form a wedge-shaped entrance to which the excess of ink is carried by the roller surface to form a thin, uniform film of printing ink which adheres to the resilient surface of the roller.
  • the thin, flat rectangular body of the metering member is positioned almost tangent to the roller surface so that ink impinges against the thin side or edge of the member.
  • the member When positioned such that the angle between the metering member and a tangent is less than thirty degrees the member is rigid in a tangential direction and flexible in a radial direction.
  • a trapezoidal shaped metering portion is formed on the thin edge of the metering member to establish an optimum geometric relationship to meter ink and to separate the metered ink from the metering member while the metering member is held substantially tangent to the resilient roller surface.
  • the metering member is mounted such that two polished flexible edges on the trapezoidal shaped metering portion are separated by a support surface and move radially relative to the axis of the resiliently covered roller.
  • the edges are resiliently urged toward the resilient surface of the roller to maintain a substantially constant metering relationship relative to the roller surface along the entire length of the roller and circumferentially thereabout.
  • the polished flexible edges of the metering member are, therefore, rigidly supported in a direction generally tangent to the roller surface and the trailing edge is oriented to deform the resilient roller surface to minimize wetting of a substantial surface area of the metering member downstream from the polished trailing edge to cause separation of ink from the metering member adjacent the polished trailing edge.
  • the trailing surface on the trapezoidal shaped metering portion of the metering member is shaped such that ink on the indented resilient roller surface does not separate from the roller surface and attach itself to the trailing surface of the metering member when rebounding from a compressed position occupied as a result of passing the flexible polished trailing edge of the metering member.
  • a primary object of the invention is to provide an inking system for printing presses affording continuous precision control of the thickness of an ink film delivered to a lithographic printing plate to eliminate ghosting and resultant variation in color of printed images, which in turn caused considerable waste of time and material.
  • Another object is to provide an inking system in which a polished edge, formed between a metering surface and a support surface which intersect at an obtuse angle is urged into pressure indented relation with a resilient roller surface such that the pressure and specific angle of the metering surface relative to the roller surface at the metering edge is selected to form a particular ink film thickness required of a particular ink viscosity carried by a roller surface past the polished edge.
  • Another object of the invention is to provide a metering member having a metering surface and a support surface intersecting at an obtuse angle to form a metering edge which is indented into a resilient roller surface having improved surface characteristics to minimize wear between adjacent surfaces and to provide improved metering.
  • Another object of the invention is to provide an improved ink metering portion on a member and resilient support means associated therewith to position the metering portion relative to a resilient roller surface for forming an ink film on the roller surface, the thickness of the film being substantially independent of the speed of the roller surface to eliminate changes in film thickness with changes in roller speed and to eliminate streaks caused by minor velocity variations of the roller as it is rotated.
  • Another object of the invention is to provide an . improved ink metering member particularly adapted to be urged into pressure indented relation with an applicator roller such that foreign matter in ink moving toward the metering surface on the metering member and carried by the surface of the form roller is diverted away from the metering member and contained or captured in a vortex of ink adjacent the metering member.
  • Another object of the invention is to provide a metering member having two smooth, superfinished surfaces intersecting to form an obtuse, blunt, smooth, superfinished metering edge capable of metering a thin, uniform ink film suitable for lithographic printing application to a printing plate.
  • Another object of the invention is to provide an improved method and apparatus for continuously forming a uniform film of ink on the surface of a resilient roller wherein the ink is metered through a wedge defined between the resilient roller surface and a metering surface, adjacent a flexible polished edge, resiliently urged toward the resilient roller surface so that the wedge automatically moves radially of said roller such that the thickness of the film of ink is substantially independent of the surface runout and waviness of the roller and does not substantially vary circumferentially and longitudinally of the roller surface.
  • a still further object of the invention is to provide an improved method and apparatus for forming a uniform film of ink on the surface of a resilient roller by use of an edge mounted on a cantilever, the edge being moved into pressure relationship with an ink film on the roller surface past a threshold point where the ink film ceases to decrease in thickness when an increase in force is applied to the edge and begins to increase in thickness while becoming more nearly uniform.
  • Another object of the invention is to provide an inking system wherein a non-rotating metering member is positioned and adapted such that metered ink passing under the member does not separate and accumulate on a trailing surface of the metering member to ultimately be pulled again to the metered film to destroy uniformity.
  • Another object of the invention is to provide an - improved inking system in which a polished edge on a metering member is resiliently urged into 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 of the invention is to continuously control the temperature of the ink in the reservoir to control the shear characteristics of the ink such that a controlled uniform film of ink is metered on the roller surface.
  • Another object of the invention is to provide a specific dampening system working in conjunction with an inking system providing a lithographic printing system which continuously and automatically provides controlled quantities of ink and dampening fluid to a lithographic printing plate.
  • Another object of the invention is to provide certain rollers strategically positioned on a single applicator roller before and after printing to a plate and before and after metering by a metering member and before and/or after dampening to condition the ink and dampening fluid film or films for proper application to a lithographic printing plate.
  • Another object of the invention is to provide specific pressure relationships between the metering member and the roller surface during start, stop and run to minimize wear and streaking.
  • the numeral 1 generally designates an inker having spaced side frames 2 movably secured to side frames 3 of a printing press having a conventional plate cylinder P, blanket cylinder B, and impression cylinder I mounted therein for printing on a web W or a sheet of paper.
  • Support means 5 is provided to,adjustably secure .
  • Opposite ends of applicator roller 40 are rotatably secured to side frames 2 in suitable bearings and applicator roller 40 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 preferably substantially equal to the surface speed of plate cylinder P.
  • End dams 6 are secured to support means 5 and are urged into sealing relation with opposite ends of applicator roller 40 and member 10 forming a reservoir R from which ink is metered onto the surface of applicator roller 40.
  • One or more ink storage vibrator rollers 8a and 8b are positioned in rolling engagement with ink on the surface of applicator roller 40 for smoothing any surface irregularities which may appear in the ink film before the ink film is carried by the surface of roller 40 to the dampener D and to the surface of a printing plate P' on plate cylinder P.
  • Ink storage rollers 8a and 8b are in rolling engagement with ink on the surface of applicator roller 40 and not only smooth surface irregularities, but also change a slick metered finish to a smooth matt- like finish for conditioning the ink film for proper dampening and application to an image on a printing plate.
  • dampening fluid is applied first to the ink on the surface of the applicator roller 40 and thence to the printing plate P' on plate cylinder P.
  • Means are provided for evaporating dampening fluid from the surface of roller 40 to prevent accumulation of excessive dampening fluid in reservoir R.
  • a hollow perforated or slotted tube 9 extends transversely between side frames 2 and has apertures formed therein through which dried compressed air is delivered for causing a stream of dry air to be directed toward the surface of roller 40. At least one end of tube 9 is connected by a hose to a suitable air supply (not shown).
  • dampening fluid when dampening fluid is used with the inker of the present invention, a greater than normal proportion of alcohol to water may be employed to print with less water and to speed evaporation of the dampening fluid ' which remains on the applicator roller as it moves away from the printing plate.
  • the dampening solution could contain more than the normal 5 to 25% alcohol to insure rapid evaporation of the dampening solution from the applicator roller as it travels between the plate and the ink metering member.
  • flexible tubes 7 are connected to deliver a fluid, such as water at a controlled temperature 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'.
  • the physical properties of ink film 130 formed between metering member 10 and resilient cover 44 of roller 40 and of ink in reservoir R may be further controlled by temperature control of a fluid passing through vibrators 8a, 8b or 8c and through the passage in the core 42 of roller 40. It has been found that a high flow rate produces only a small temperature change along the length of a roller and that by monitoring and controlling the output temperature, heat can be dissipated and ink temperature controlled such that the physical properties of the generated film are held substantially constant throughout the length of a production run.
  • the ink viscosity at and prior to nip N is controlled to maintain a constant desirable ink film for proper printing to plate P.
  • ink metering member 10 A preferred embodiment of ink metering member 10 is illustrated in Figures 3 and 4 of the drawings.
  • the ink metering member 10 has a smooth, polished, highly developed, precision metering edge 25 which is formed at the juncture of metering surface 24 and support surface 26.
  • Metering edge 25 preferably extends in length for a distance within a range of from 10 to 80 inches, depending upon the press width, and is defined by the intersection of the polished surfaces 24 and 26. Polished surfaces 24 and 26 meet at an obtuse angle to form a wedge having an included edge bevel angle "AI "which is approximately 120° or greater.
  • the edge 25 is preferably formed on relatively hard metallic material having a hardness of about Rockwell C48-50 or higher. It is important that the polished edge 25, metering surface 24, support surface 26, trailing surface 28a and edge 28b be wear resistant since they are indented into the resilient surface 45 of form roller 40 during normal operating conditions.
  • Metering member 10 is preferably a resilient, i.e., flexible, metallic, material having a modulus of elasticity of approximately 30 x 106 psi, or less, to provide what might be termed a "stylus effect" to the metering edge 25 as the form roller 40 rotates.
  • Metering member 10 has been formed with good results from a strip of stainless spring steel with sheared edges which is commercially available from Sandvik Steel, I nc., Benton Harbor, Michigan, and distributed as Sandvik 7 C 27 M o2.
  • the strip of stainless steel was selected for its hardness, flatness, resilience, grain structure and fine surface finish to provide high wear resistance and good fatigue properties.
  • the stainless steel strip had a thickness of 0.070 inches and a width of approximately 5.3 inches.
  • the strip of material had been heat treated and had a bright polished surface finish, extra accurate flatness and normal straightness.
  • the tolerance of the width was + 0.016" and the tolerance of the thickness was + 0.00181 inches.
  • the strip of stainless steel material was resistant to corrosion in the presence of air, water and most organic acid in dilute form at room temperature. The tensile strength was about 249,000' psi corresponding to the hardness of R ockwell C 49.
  • edges 24 and 26 were ground at a specified obtuse angle, then finished with a fine-grit stone as will be hereinafter more fully explained, as a first step in forming polished edge 25.
  • the strip was then clamped in a special fixture. Surface 24 on the strip was superfinished at the specific angle by hand with a fine grit stone and then hand polished with 600 grit sandpaper.
  • the stainless steel strip was positioned on a flat horizontal surface.
  • Surface 26 was then superfinished by hand with a stone having a fine grit and hand polished with 600 grit sandpaper.
  • a feather edge forms on the metering member while portions of surfaces 24 and 26 are being superfinished and polished, the feather edge should be removed with leather or a polishing material.
  • a smooth, continuous, uniform, blemish-free edge is formed on the strip.
  • the acuteness of the edge may be altered somewhat to form a non-cutting, non-film-piercing edge. This process produces a fine, continuous, smooth, straight, polished, highly developed, uniform, superfinished, edge 25, having minimal surface irregularities. There should be no small notches or protrusions in the edge.
  • the developed edge 25, formed by polished surfaces 24 and 26, is an extremely fine edge which has been polished to bring it to a highly developed finish, and as nearly perfect condition as possible.
  • Surfaces 24 and 26 are preferably finished to an RMS reading not exceeding RMS 4.
  • the term "superfinishing" as used herein applies to a surface which has been ground and polished such that the peaks of the surface have been removed to form flat bearing surfaces, yet still having minute valleys or reservoirs for accepting and carrying the lubricant ink.
  • Edge 25 is finished to a surface finish approximating that of the edge of a razor blade.
  • the obtuse angle "A I " between surfaces 24 and 26 is significantly greater than the bevel angle on a razor blade and thus an obtuse, blunt, non-cutting and non-piercing edge is formed.
  • surface 24 blends into surface 26 through edge 25 to form a continuous polished surface adjacent each side of edge 25.
  • edge 25 must not only be hard and capable of being formed to provide a blunt, fine, polished, unbroken, edge, but the material must also be dense yet flexible along the length of the edge 25.
  • the edge 25 must be quite flexible in a lengthwise direction so that when urged into pressure indented relation with the resilient surface of applicator roller 40, the edge 25 will be flexed, yielding to the influence of the surface of roller 40, to conform the edge 25 and the surface of roller 40 to form a substantially uniform indented area along the length of roller 40.
  • the resilient cover 44 on roller 40 has a thickness in the range of approximately 3/8 to 5/8 inches, preferably 1/2 inch, and a resilience of about 40 to 70 Shore A durometer, preferably 60 durometer, Shore A. This loading of edge 25 to obtain conformation with the surface of roller 40 should be possible without excessively indenting the surface of the roller when in a dynamic, running condition.
  • the edge 25 on metering member 10 should be mounted so that it is resiliently urged toward the surface of the applicator roller 40 and is free for movement along its entire length in a direction radial to the applicator roller. Also, the edge 25 must be rigidly supported in a direction substantially tangent to the applicator roller surface.
  • the ideal support for the edge 25 is a flexible cantilever beam which supports the edge 25 and provides the required bias and rigidity.
  • the edge 25 may be a part of a separate trapezoidal like element, which is functionally associated with a cantilever beam, it is preferable to form the edge 25 of the trapezoidal portion 10 on the beam so that the two are an integral unit.
  • the beam must be flexible in two directions; namely, along the length of the edge 25 and also along the width of the strip, ie., the length of the cantilever beam.
  • the ink metering member illustrated in Figure 4 of the drawing wherein the edge 25 is formed on the unsupported end 10'of the cantilever beam, has a substantially rectangular cross section bounded by front and rear edge surfaces 22 and 22', upper surface 28 and lower surface 29.
  • Support surface 26 lies substantially in the plane of surface 29, when the cantilever beam is in a non-flexed condition.
  • Metering surface 24 and support surface 26 intersect forming an obtuse angle "A l " and intersect at an apex 25, which is substantially a straight line.
  • the cantilever beam which includes the obtuse edge 25 may be formed from a thin, flexible, elongated stainless steel strip or band, as hereinbefore described, having a thickness of 0.070 inches and a width of 5.3 inches, or less.
  • the width of the beam, or the length of the strip of material will preferably be within the range of from 10 to 80 inches, and the beam is supported to be flexible along the length of edge 25 as well as along the length of the cantilever beam.
  • the modulus of elasticity E of the beam may be, for example 29 x 10 6 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 represents the stiffness of the cantilever beam.
  • Metering member 10 also has a groove or relieved area 27 formed in the lower surface 29 of the strip of material from which metering member 10 is formed.
  • the portion of the strip of material which will be polished to form polished edge 25 is masked and the metallic material adjacent thereto is removed by grinding or by chemically milling to remove a portion of the metal without creating stresses that would cause the strip of material to warp.
  • Edge 28a adjacent the support surface 26 is smoothed by finish grinding to remove approximately 0.003 inch of rough surface material.
  • Surface 28a may then be sanded with 600 grit paper to provide a very smooth surface finish on the surface of 28a.
  • Edge 28b is therefore formed as discussed previously for edge 25.
  • the depth of the relieved area 27 is preferably greater than 0.020 inches, for example, 0.035 inches, such that the thickness of the material between surface 28' and surface 28 is approximately 0.035 inches.
  • Surface 28a intersects the polished surface 26 at an angle A' in a range between 30° and 90° as shown.
  • the upper portion of surface 24 of metering member 10 may extend to surface 28 or be bevelled as shown at an angle to form surface 22.
  • Obtuse angle "A 1 " not only forms a metering member having a blunt, obtuse, edge which is not fragile, but, primarily is specifically formed to a particular angle, or configuration, to enable the metering of a specific ink film thickness having a specific viscosity and strength of color to meter the film without an im 7 mediate change in direction of the roller surface and without significant indentation of the roller cover which causes rapid wear of the metering member edge and the roller cover.
  • polished surface 24 extends upwardly from polished edge 25 a distance approximately equal to the depth of relieved area 27, or greater, to intersect surface 22. It should be readily apparent that polished surface 26 supports the polished edges 25 and 28b. If surfaces 24 and 28a are parallel, surface 26 can be refinished without changing the load bearing characteristics of the polished edge portion 25 of the metering member 10.
  • edges 26 and 28a are readily renewable.
  • both edges may be resharpened simultaneously; or, surfaces 24 and 26 may also be refinished.
  • a small radius or curve may appear at edge 25 to cause changes in metering characteristics.
  • post-grinding and hand-finishing procedures may be again performed several times before the entire member is replaced. Normally one to three thousandths of an inch is removed from any one surface, depending upon the extent of wear to restore edges 25 and 28b.
  • a special fixture or fixtures may be used when refinishing surfaces 24 and 26 in order to prevent damage to the metering member.
  • the fixture should not only hold the member, but also provide guide surfaces for the fine grit stoning and sanding operations to insure that only a minimum amount of material is removed and that the obtuse angle "A l " and edges 25 and 28b are maintained.
  • the relief angle A ' should be sufficient to cause any ink film carried by the surface of roller 40 to depart and separate from surface 26 without accumulating either on surface 26 or 28a to cause ultimate dripping of the accumulated ink to cause non-uniformity of printing.
  • the applicator roller 40 comprises a hollow, rigid, tubular metallic core 42 having a resilient non-absorbent cover 44 secured thereto, the cover having a uniformly smooth, uniformly textured, and resilient outer surface 45.
  • the cover 44 on applicator roller 40 while being resilient, is relatively firm, for example, in a range between 40 and 70 Shore A durometer.
  • the cover 44 on applicator roller 40 is preferably formed of a resilent urethane, polyurethane rubber or rubber-like material attached to a metallic core 42.
  • the cover is made from Buna Nitrile rubber which provides a natural surface having microscropic pores to receive and hold ink therein to enable metering a thin ink film suitable for lithographic printing applications.
  • the cover 44 on applicator roller 40 should have high tensile strength, excellent tear and abrasion resistance, and resistance to oils, solvents and chemicals.
  • the cover should, furthermore, have low compression set, good recovery, and uniform ink receptivity.
  • a suitable cover can be formed using urethane or rubber to form a resilient cover preferably of about 60 Shore A durometer.
  • a suitable urethane cover may be made from a blocked, pre-catalized material which is commercially available from Arnco in South Gale, California, under the trademark "Catapol". The material is pre-heated at 160°F for five hours, poured into a mold around the roller core, and then heated to 280°F for 8-1/2 hours, and allowed to cool prior to grinding and polishing.
  • a suitable rubber cover may be obtained from Mid-America Roller Company, Arlington, Texas, and specified as Buna-Nitrile which is conventionally formed over the core and ground with a high-speed grinder prior to polishing.
  • the roller may have a slick glazed outer skin or film over the surface thereof which is removed by grinding.
  • the surface of resilient cover 44 if constructed of urethane, is sanded by using 180 grit sandpaper to form a surface of uniform smoothness over the surface 45 of the resilient cover 44.
  • the surface of resilient cover 44 if constructed of rubber is sanded with 400 grit sandpaper to insure a velvet smooth, uniformly textured surface, free of "orange peel" or other surface irregularities.
  • Microscopic reservoirs into which ink is attached help to assure that a continuous unbroken film of ink is maintained on the surface 45 of applicator roller 40.
  • roller 40 it will be appreciated that it is physically impractical, if not impossible, to construct and maintain roller 40 such that surface 45 is perfectly round in a circumferential direction, perfectly straight in a longitudinal direction, and precisely concentric to the axis of core 42.
  • the straightness or waviness of surface 45 on roller 40 can be economically manufactured within a tolerance of about 0.002 inches along the length of roller 40 and the - radial eccentricity can be economically manufactured within a tolerance of about 0.0015 inches.
  • a Shore A durometer test is generally used to indicate the hardness of a resilient roller cover by measuring resistance to penetration at a constant temperature of about 76°F while the resilient cover is stationary.
  • the apparent hardness of a resilient surface under dynamic conditions deviates radically from the hardness indicated by the durometer test under static conditions.
  • the spring constant of a resilient material so increases slightly as deformation increases.
  • roller 40 can be different in diameter than the plate cylinder P without adversely affecting printing of the film 130 to the web W , or sheet, since metering member 10 produces a continuous ribbon of ink on the applicator roller surface regardless of the prior impression and regardless of thermal changes within the roller cover 44.
  • the applicator roller 40 should not be the same diameter as the plate cylinder P, because even the slightest defect, hole, flaw, etc. in the surface of the applicator roller 40, would repeat in the same place on the plate when the two are driven at the same surface speed and are the same diameter; i.e., repeat on a one-to-one basis.
  • This repeat especially when printing to a lithographic plate, eventually causes sensitizing of the non-image area.
  • the flaw will then appear as ink on the printed sheet in the non-printing area. If the flaw occurs in the printing area, eventually heavy ink will appear in this area. Therefore, it is imperative that the surface of the applicator roller 40 not repeat with the surface of the plate on the plate cylinder. It has been observed that with the absence of a repeat, the flaw, even when considered excessive, will not sensitize a lithographic plate in the non-printing area.
  • support means 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 surface 54 angularly disposed relative to flat face 52 forming a shoulder 55 which extends longitudinally of support bar 50.
  • Journals 56 extend outwardly from opposite ends of support bar 50 and are rotatably secured in self-aligning bushings 57 (not shown) 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.
  • Lateral adjustment screws 66 extend through threaded apertures in outwardly extending lugs 68 on inker side frame 2 and engage end surface 66' on projections 58.
  • bearing block 60 is adjustable vertically and horizontally, as viewed in Figure 1 of the drawing, for 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 piston rod 71 of fluid pressure actuated cylinder 72 into engagement with an end of a stop screw 74 threadedly secured to an arm 75 bolted or otherwise secured to bearing block 60. It should be readily apparent that support bar 50 is rotatable relative to bearing block 60 by adjustment of the position of the end of stop secrew 74 relative to arm 75.
  • Pressure regulator R" is installed in order to set inlet pressure in cylinder 72 sufficient to hold arm 70 firmly against screw 74 for all indentations of edge 25 into surface 45 of cover 44.
  • Metering member 10 is secured to the flat surface 52 on support bar 50 by bolts 76 extending through spaced apertures in clamp member 78 and through oversized spaced apertures extending through the cantilever beam adjacent the rear edge thereof.
  • Bolts 76 are threadedly secured in threaded passages formed in support bar 50.
  • Bolts 76 and clamp 78 cooperate such that the metering member 10 is uniformly attached or supported by support-bar 50 such that the edge 25 has a uniform spring rate along its length.
  • stop screw 74 is remotely controlled by a direct current electrically driven motor 80 secured to arm 75 by a support bracket 81.
  • a gear reducer is positioned between motor 80 and screw 74 to further control the speed of rotation of screw 74.
  • a splined coupling 76 is connected between screw 74 and the output shaft of motor 80.
  • Motor 80 is commercially available from Globe Industrials Division of TRW, Inc., of Dayton, Ohio.
  • Conductors 82 and 84 extend between motor 80 and motor position control unit 85 which is of conventional design and comprises a direct current source and a three position switch.
  • Motor position control unit 85 has a digital readout indicator 86 associated therewith to indicate the position of a rotary potentiometer (not shown) at the end of stop screw 74 which engages arm 70 to provide visual indication of the position of the support 50 for metering member 10.
  • Motor 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 is preferably positioned adjacent the delivery end of the printing press or at a control console so that the position of metering member 10 can be adjusted remotely as printed sheets are inspected to adjust overall color density of ink as required.
  • Inker side frames 2 are pivotally secured by a shaft 90 to press side frames 3 adjacent opposite sides of the printing press.
  • a fluid pressure actuated throw-off cylinder 92 is pivotally secured to lugs 93 secured to side frames 3 of the printing 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 properly established.
  • An off-stop adjustment screw 98 is threadedly secured to a lug welded or otherwise secured to printing 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 l .
  • 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 applicator roller 40, as illustrated in Figures 1 and 2 of the drawing, and has opposite ends secured to end dams 6.
  • the lower edge 102 of ink retainer member 100 is preferably spaced slightly from surface 22 on ink metering member 10.
  • Ink retainer member 100 defines the entrance side of reservoir R.
  • the exit side of reservoir R is defined by member . 105 secured to support bar 50 by bolts 106.
  • the lower seal 108 adjacent member 105 is positioned adjacent the upper surface 28 of metering member 10 to prevent flow of ink from reservoir R onto the upper surface 28 of metering member 10 to form an area of stagnation in which ink ceases to flow. Since lithographic ink is thixotropic, the viscosity of ink is significantly reduced when the ink is in motion as compared to the viscosity of ink which is not in motion.
  • a conventional agitator 110 is secured to ink retainer member 100 for agitating ink in reservoir R.
  • Ink agitator 110 is commercially available from Baldwin-Gegenheimer of Stamford, Connecticut, and comprises a rack and pinion (not shown) which extends longitudinally across the upper portion of the reservoir R which carries a mixing head driven through a chain by a constant speed motor. As the mixing head approaches an end dam 6 adjacent one end of applicator 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.
  • Elevating screws 64 are employed for paralleling face 52 to axis C and for adjusting the angular relationship between surface 26 on metering roller 10" relative to a tangent to a radial line of applicator roller 40 passing through edge 25.
  • Lateral adjustment screws 66 are employed for moving bearing block 60 relative to applicator roller 40 for alignment of edge 25 on metering member 10 relative to surface 45 on resilient cover 44 of applicator roller 40.
  • anchor bolts 52/a' After edge 25 on metering member 10 has been aligned with the surface of applicator roller 40 and the angular relationship between surface 26 and a line tangent to applicator roller 40 has been established, anchor bolts 52/a're tightened, rigidly securing bearing blocks 60 relative to side frames 2.
  • edge 25 on metering member 10 now intersects surface 45 on cover 44 of roller 40 at Point P" at a position of about eleven o'clock; that is, in the nine to twelve o'clock quadrant, assuming zero and twelve o'clock to be at the extreme top of the applicator roller 40 and numbering clockwise as the numbers on the face of a clock.
  • Reservoir R is therefore formed as shown, which naturally, because of gravity, causes ink to be weighted against edge 25 of metering member 10 to ensure complete submergence of ink on the frontal surface of metering member 10 at roller surface 45 on cover 44 of roller 40 at Point P".
  • Edge 25 is now positioned in "kiss" contact with the surface 45 of applicator roller 40. An amount of ink in excess of that needed to continuously ink the plate P' on the plate cylinder P is provided from the reservoir R to the surface of the applicator roller 40 which is approaching metering surface 24 on metering member 10.
  • 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 position illustrated in dashed outline.
  • Support width S was 0.15 inches.
  • the modulus of elasticity E of the metering member 10 was approximately 30 x 10 6 psi.
  • the moment 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 moment of inertia I of metering member 10 having a thickness of 0.035 inches is calculated to be 3.5 x 10- 6 per inch of width of the cantilever beam.
  • the deflection of the unsupported end of the cantilever beam should be approximately 0.31 inches when a load of twenty-five pounds per inch of width is applied to the edge 25. Consequently, , it was concluded that the spring constant for the cantilever beam would be 0.012 inches of deflection per pound of force applied to the edge 25 or 81 pounds per inch of deflection on one inch of the width of edge 25.
  • edge 25 is resiliently urged in a direction radially of applicator roller 40.
  • the spring constant calculated from the actual deflection of resilient member 10 differs from the approximate spring constant calculated above. However, the differences in the spring constant as approximately calculated and as actually measured was predicted.
  • the wide support surface S of 0.15 inches was selected as such to provide an adequate support area to correspond with the large twenty-five pound force acting on surface 26 of metering member 10 and on the applicator roll cover 44 in the depressed area indicated by N on the film of ink generated at edge 25, creating a pressure at N sufficient to indent the entire surface 26 and both edges 25 and 28b into the surface 45 of cover 44 of applicator roller 40.
  • Static indentation was measured to be approximately 0.06 inches which immediately changed to 0.04 inches upon rotation of a 60 durometer applicator roll having a one-half inch thick cover 44.
  • edge 25 of the cantilevered portion of metering member 10 a certain force is required, and for that force, a given support surface is required which will provide a pressure to adequately indent a particular roller cover an amount sufficient to form between the roller surface and the metering surface at the first edge of the metering member, a wedge or orifice to meter a particular ink of a known viscosity to a desired film thickness as the film exits the second trailing edge of the support surface.
  • small edge deflections require small forces to obtain -the small deflection and can be supported by a small support area to adequately provide pressure sufficient to indent a particular cover a desired amount.
  • Figure 3 shows both a large support surface width S and a small width S'.
  • S is shown to be greater than t, i.e., approximately 2t while S' is shown to be equal to or less than t, i.e., approximately t. Satisfactory results have been obtained with S between t and 2t.
  • Large edge deflections are also desirable in order to provide a system which is responsive but yet not too sensitive to changes in position of stop screw 74.
  • the combined distance that the edge 25 is deflected plus the distance that edge 25 is indented into the roller surface 45 should be substantially greater than the maximum space between points on roller surface 45 and edge 25 when the surface and the edge are urged into kiss contact.
  • irregularities or manufacturing imperfections in roller surface 45 and slight waviness of edge 25 might easily result in a maximum deviation of 0.002 inches error such that the surface 45 and edge 25 do not conform when first touched together.
  • edge 25 is deflected 0.16 inches and indented into surface 45 a distance 0.04 inches in a dynamic condition, the initial deviation of 0.002 would be only 1% of the combined distance of 0.20 inches. Since edge 25 and cover 44 are resilient, the edge and the surface will flex and conform to each other. When thus conformed, pressure along the stripe area N will be substantially constant and the effect on the ink film of small differences will be insignificant.
  • the edge 25 on metering member 10 is urged into pressure indented relation with the surface of applicator roller 40 such that the resilient material is built up, up-stream from surface 24 forming a small bulge or wave 120 in the cover 44 while a groove or channel 27 is formed in the cover downstream from edge 25.
  • the area in front of surface 24 forms a wedge through which ink is drawn; the wedge being bounded on one side by a portion of surface 24 and edge 25 and bounded on the other side by a portion of the surface 45, probably between a small portion of the bulge 120 and the portion of the surface 45 immediately adjacent polished edge 25.
  • the wedge automatically moves minutely radially relative to the axis C of the applicator roller 40. Since the wedge is formed by the cooperation of the opposing flexibly biased edge 25 and resilient surface 45 of the applicator roller 40, this movement is desirable if a constant pressure relationship is to be maintained on the ink extruded through the orifice.
  • the surface of the applicator roller 40 will constantly change in contour as the roller rotates due to elastic memory, temperature changes, and variations in the dynamic modulus of elasticity, as hereinbefore discussed. Consequently, it is important that the edge 25 automatically move radially and flex lengthwise to follow this changing contour.
  • the resilient edge 25 of metering member 10 and resilient cover 44 of roller 40 might also be viewed as two opposing springs each having a particular spring constant K l and K 2 , respectively.
  • the combined spring constant K is equal to which is less than either K l or K 2 .
  • Table 1 and resulting calculations are proof of the above statement of K being less than K 1 or K 2 and further shows that the initial 0.002 inches error results in a final pressure error of only 1% of the static or dynamic pressure.
  • surface 24 is formed on the rectangular cross section, the working end of metering member 10, as seen in Figure 4, forms a trapezoidal like shape 10".
  • ink carried by the surface 45 of applicator roller 40 impinges against metering surface 24 and surface 22 creating a region of turbulent flow adjacent the crest of the bulge 120 on the resilient roller surface.
  • edge 25 is resiliently urged downwardly as viewed in Figure 3
  • metering surface 24 is shaped and positioned and edge 25 is sufficiently resiliently loaded against roller 40 to prevent changing of film 130 by hydrodynamic forces exerted on metering member 10 by the ink.
  • This condition is also assisted by positioning polished edge 25 such that it is closer to the central axis C of applicator roller 40, or the same as any other point of surface 26 of metering member 10.
  • the blunt, obtuse polished edge 25 favorably deforms the resilient cover 44 on applicator roller 40 to form a metering wedge angle W between surfaces 24 and 120 for forming a film of ink of precisely controlled thickness having an approximate pressure profile as shown in Figure 3 where the maximum pressure occurs at the first edge 25.
  • Surface 28a on metering member 10, immediately downstream from surface 26, is positioned so that the metered film of ink is in contact with metering member 10 only along surface 26 to cause the ink film 130 to immediately separate from metering member 10 at edge 28b to prevent trailing of the ink along surface 28a which would result in accumulation of ink, dripping, and consequently, erratic flow which would destroy the uniformity of film 130.
  • the lower surface of metering member 10 has been formed such that surface 28a at the heel 28b of polished surface 26 and bounding relieved area 27 is angularly disposed relative to the direction of movement of ink film 130 such that roller surface 44 cannot rebound to a position wherein ink film 130 contacts surface 28' or accumulates on surface 28a.
  • the metering member is shaped and positioned to cause ink film 130 to immediately separate from the metering member returning to its relaxed, non-indented, position.
  • edge 25, is shown to be indented an amount equal to d into the applicator roller surface 45 whose original radius is R having a surface velocity. V, cover thickness T and durometer D.
  • Metering member 10 as shown in Figure 4 has a support surface width S, thickness t and relief r leaving a cantilever height of t - r.
  • Distance L represents the cantilever and 1 the length of the relief.
  • Metering surface 24 is inclined at an angle B to a height of t - h.
  • Angle "A 1 " is the total included obtuse angle between surfaces 24 and 26 and is equal to 90°+B.
  • angle "A3” represents the slightly inclined angle of surface 26 relative to a line parallel to a tangent to the roller radius R by the distance equal to indentation d measuring from P".
  • Point P " represents the point of intersection on radius R of surface 45 of a radial line and a tangent to the roller.
  • Angle "A3” is preferably 0°, or slightly greater, to insure that edge 25 is indented an amount equal to or greater than any other point of surface 26.
  • Nip N represents the ink between the support surface 26 of metering member 10 and the depressed roller surface in the zone between edges 25 and 28b represented by support-width S.
  • N is substantially the same as film 130 generated past edge 28b on roller surface 45 which varies according to parameters previously mentioned.
  • a 2 is the angle between surface 24 and a radial line passing through Point P" and is equal to B plus "A3" .
  • Angle W is the wedge or entrance angle between surface 24 and a tangent to an imaginary circle or curve having a surface 120 moving towards edge 25.
  • the invention disclosed herein as seen in Figure 3 causes an almost instantaneous or sudden increase in pressure on the roller cover as the obtuse first edge 25 indents the oncoming rotating roller, with the pressure reaching a peak or maximum P M and then suddenly reducing somewhat as the roller passes the edge 25 and under the support surface 26 of the metering member and then again reducing rapidly to zero pressure as the roller exits the trailing edge 28b of the member.
  • the maximum pressure P M of the metering device 10 disclosed herein is reached at the obtuse, first metering edge 25, of the metering member 10 and not at the second, trailing edge 28b, as in prior art paper coating applications.
  • first metering edge 25 of the metering member 10 is reached at the obtuse, first metering edge 25, of the metering member 10 and not at the second, trailing edge 28b, as in prior art paper coating applications.
  • the rigid tangential support of the edges and the flexible radial support thereof co-act to provide automatic consistency and uniformity of metering as the roller rotates even when the speed is caused to vary.
  • FIG. 3 shows metering member 10 in such indented relation with surface 45 of roller 40 at a position such that edge deflecting load, pressure (which determines indentation), and therefore, ink film thickness (which determines color) is substantially constant.
  • the thickness of ink film 130 varies as a function of the indentation of polished edge 25 into resilient surface 44- of applicator roller 40. As described above, as the indentation increases, the thickness of ink film 130 decreases rapidly to a minimum and then begins increasing. Irregularities or imperfections in surfaces on metering member 10 and applicator roller 40 are easily seen in the metered ink film 130 until polished edge 25 is indented to a point where the variation in the initial edge to roller relationship along the length of edge 25 is small, as related to the total deflection, for example, less than plus or minus five percent. At this point, the ink film becomes more regular and uniform and remains substantially uniform as polished edge 25 is further deflected and indented into the surface of applicator roller 40.
  • the thickness of the minimum ink film is controlled primarily by the pressure at edge 25 and by the angle of metering surface 24 relative to the roller surface 120 indicated by W at Figure 3 for a particular ink viscosity
  • metering surface 24 is established by angles B and "A3", so that metering surface 24 leans toward the crest of bulge 120, in a counter-clockwise direction as viewed in Figure 3.
  • the minimum film thickness indicated in Figure 5 is established for a particular roller durometer and thickness, metering member support surface width, loading and ink viscosity.
  • the thickness of film 130 can be changed somewhat by varying viscosity of ink in reservoir R.
  • the viscosity of ink in reservoir R can be adjusted to adjust film thickness which changes color. Viscosity or the rheology of the ink may also be altered somewhat to change color through the use of reducers and/or extenders.
  • the generally recommended or desirable color density for cyan is 1.25; for magenta, 1.30; for black, 1.60; and for yellow, 0.90.
  • the range should be approximately f 15 density points or a total of 30 density points.
  • 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.
  • Ink generally employed for printing newspapers has a viscosity in a range of about 50 to 80 poise.
  • Ink generally employed for letterpress printing and heat set inks employed for web offset printing have a viscosity in a range of about 150 to 200 poise.
  • I nk employed in sheet-fed lithographic offset printing presses is generally in the range of 250 to 300 poise.
  • Flow of ink in the reservoir toward the metering member is turbulent due to the structure of the metering member adjacent the reservoir, thus causing lint and other foreign matter to generally be rejected from an area of high pressure immediately adjacent the leading edge of the metering member. This lint and foreign matter is retained in the vortex of the reservoir and therefore lodging of particles against the edge of the metering member is minimized.
  • Flow of ink carried by movement of the surface of the resilient roller toward the first polished edge of the metering member experiences an almost instantanteous increase in pressure and turbulent flow becomes laminar immediately adjacent the first polished edge. Shearing of the ink is accomplished as it moves through a wedge between the resilient surface of the roller and the metering surface on the metering member adjacent the first polished edge.
  • the polished support surface and edges on the metering member are urged toward the resilient surface of the applicator roller by a force sufficient to indent the roller surface along the length of the edges and along the length of the roller surface.
  • the required indentation is dependent upon the film thickness desired; the modulus of elasticity of the resilient roller cover; the thickness of the resilient roller cover; the temperature, strength, tack, and viscosity of the ink and other rheological characteristics and properties of the ink; the texture of the roller surface; the condition of the leading edge of the metering member; the support surface width; the angle of the metering surface of the metering member; the position of the support relative to a line tangent to the roll; the pressure between the applicator roller and the adjacent plate; conditioning of the ink prior to and after application to the plate; and fountain solution present in the ink being metered and fountain solution added to the metered ink film.
  • the polished edges of the metering member slightly indent the surface of the resilient roller, for example about one-thirty second of an inch on a 60 Shore A durometer roller having a cover thickness of approximately 1/2 inch.
  • the flexible-polished edges of the metering member move relative to the axis of the roller to maintain a condition of equilibrium such that the edges automatically move radially along their length relative to the axis of the roller surface and circumferentially thereabout although the roller surface is not perfectly round and not free of slight waviness.
  • Figure 7 diagrammatically illustrates the phenomenon hereinbefore discussed which results in increasing uniformity of color density of ink on a printed sheet as the force resiliently urging edge 25 into pressure indented relation with the surface 45 on roller 40 is increased.
  • the ink film thickness decreases to a minimum and then begins to increase as force urging edge 25 into pressure indented relation with roller surface 45 is increased.
  • the same ink film thickness is achieved at two different points on the curve.
  • variation in color density is different at the two points on the curve.
  • a dial indicator was attached to support bar 50 and positioned in engagement with the upper surface 28 adjacent metering surface 24 on metering member 10.
  • a total dial indicator reading of 0.002 inches was observed. This indicated that the runout in the radius of the surface of roller 40 was 0.001 inches and that edge 25 on metering member 10 moved 0.002 inches upon each revolution of roller 40.
  • the surface speed of roller 40 was increased, the magnitude of movement of edge 25 re- * ⁇ mained substantially the same at different surface speeds of roller 40.
  • the total deflection of metering member 10 increased somewhat as the surface speed of roller 40 increased.
  • the edge 25 on metering member 10 automatically moves relative to the axis C of applicator roller 40 upon each revolution of applicator roller 40 in response to changes in speed and runout of applicator roller 40.
  • the system should be designed such that pressure in cylinder 72 is reduced or released when the roller is stopped. Upon starting, the air pressure should be restored to normal operating pressure against stop screw 74.
  • edge 25 to roller surface 45 will be only when the roller is rotating under edge 25 with a lubricating film of ink N therebetween. If pressure is not reduced upon stopping, edge 25 will depress roller surface 45 almost twice the amount of the running indentation.
  • ink film thickness remained substantially constant over a broad speed range and therefore is substantially independent of the surface speed of applicator roller 40.
  • metering member 10 automatically moves radially as applicator rol- l er 40 rotates.
  • metering member 10 is positioned such that metering surface 24 and polished edge 25 are rigidly supported in a tangential direction.
  • force imparted to metering surface 24 as a result of ink impinging thereagainst is directed both tangentially and radially of applicator roller 40 and force against surface 22 of metering member .10 is directed only substantially tangentially and that metering member 10 is angularly positioned such that it is very stiff in a direction generally tangential to applicator roller 40.
  • angle "A3" of surface 26 is substantially 0°, or, may be slightly greater.
  • the pressure wedge angle W produced immediately ahead of edge 25 of metering member 10 and acting against roller surface 120 and metering surface 24 because of the slight area of surface 24, cannot produce a force sufficient to lift edge 25 away from roller surface 45 or roller surface 45 away from edge 25 to cause a change in film 130 as speed is increased.
  • metering member 10 While it is necessary that metering member 10 be positioned to resiliently urge edge 25 in a radial direction, metering member 10 must be of sufficient thickness to permit formation of relief r and beam thickness t-r, metering surface 24, and polished edge 25 thereon. Metering member 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, axially loaded column.
  • the metering member 10 constructed and supported as hereinbefore described is capable of metering a film which is sufficiently thin and sufficiently uniform for inking a printing plate without rapid wear of critical components to provide very high quality single or multi-color printing. Color density can be changed immediately by merely adjusting the position of stop screw 74, which is remotely controlled.
  • the metering member 10 when properly formed and positioned causes lint and other foreign matter in the ink to be rejected from the wedge formed between surface 24 of metering member 10 and the surface 120 of applicator roller 40.
  • Metering surface 24 and surface 22 form a barrier above the edge 25 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 25, lint and foreign matter will tend to be rejected from this area if a low pressure path is provided in the reservoir.
  • Reservoir R is preferably at atmospheric pressure. Also light foreign particles become entrapped in the center of the vortex created in this low pressure area.
  • edge 25 is hydrostatically supported by ink carried by roller surface 45.
  • any tendency for the metering member to move away from the roller and vice versa is quickly and automatically overcome by opposing spring forces applied against each other when both the roller cover and metering member are resiliently spring biased together as described herein.
  • the stiffness of the working end 10' of metering member 10 influences uniformity.
  • the metering edge 25 on the blade must be deformible across the length of the applicator roller 40 to accommodate manufacturing imper- fections in the roller surface to provide lateral uniformity.
  • Test data indicates that the ink film 130 will increase in thickness in response to: (1) an increase in indentation of metering edge 25 into the cover of the applicator roller; (2) a reduction in the area of support surface 26; (3) an increase in force urging metering edge 25 toward the axis C of the applicator roller; (4) a reduction in the durometer of the cover 44 on the applicator roller; (5) an increase in the radius of curvature of metering edge 25; (6) an increase in the thickness of the cover 44 on the applicator roller; and (7) an increase in the angle "K 2 " between metering surface 24 and a line R extending radially of the applicator roller.
  • a film 130 of sheet fed printing ink was too thick using a metering member having an angle A l of 120° on a thirty durometer roller.
  • the thirty durometer roller was replaced with a sixty durometer roller and the ink film 130 was too thin.
  • the metering member having an angle A 1 of 120° was replaced with a metering member having an angle A l of 130° and the ink film was satisfactory on the sixty durometer roller.
  • Metering surface 24 influences the metering of inks of different viscosities and a change in the angular relationship of metering surface 24 relative to the surface of the applicator roller will change the ink film thickness.
  • the primary reason metering surface 24 significantly influences the ink film thickness is that metering surface 24 intersects support surface 26 at an apex and is not significantly rounded.
  • the thickness of ink film 130 is primarily determined by the relationship of metering surface 24 and metering edge 25 relative to the surface of the applicator roller.
  • support surface 26 does not significantly influence the thickness of the film of ink 130 formed on the applicator roller.
  • Experimental data reflects that, within limits, the angular relationship of support surface 26 relative to the radial line R does not in of itself change the ink film thickness.
  • the trailing edge 28b does not appear to influence film thickness.
  • surface 28a and support surface 26 must intersect at an apex so that the metering member 10 abruptly separates from the surface of the applicator roller so that ink will not accumulate on surface 28a.
  • metering surface 24 and support surface 26 The angular relationship between metering surface 24 and support surface 26 and the orientation of metering surface 24 and support surface 26 relative to the surface 45 of applicator roller 40 are critical. As hereinbefore described, a primary consideration in selecting the angle "A l " between the metering surface and the support surface is the viscosity of the ink which is to be metered.
  • Example II it will be noted that a metering member having an angle of 150° between metering surface 24 and support surface 26 was selected for metering letterpress ink which has a very low viscosity which.might be referred to as "water-like.” Lithographic printing ink has a higher viscosity than does letterpress ink and it will be noted that in Examples I and III that the angle "A I " between metering surface 24 and support surface 26 was significantly less than the angle "Ai" of the metering member used for metering letterpress ink.
  • the width S of the support surface 26 does not in and of itself control the thickness of the film of ink formed on the applicator roller.
  • the width of the support surface 26 is selected to provide the desired indentation of metering edge 25 into the resilient roller surface when a force of a predetermined magnitude is exerted on the metering member.
  • the force urging metering edge 25 into pressure indented relation with the surface of applicator roller 45 should be sufficient to maintain metering edge 25 indented into the resilient roller surface, to permit some movement of metering edge 25 radially of the roller as the roller rotates, but sufficiently great to provide uniformity and to prevent uncontrolled vibration or chatter of metering edge 25 as the roller rotates. Since indentation of metering edge 25 is primarily a function of the pressure which is equal to force divided by the area of the support surface, the area of the support surface which is required for establishment of particular parameters can be established and the sensitivity of the device controlled.
  • the viscosity of the ink can be adjusted slightly by adding chemical thinners or thickening agents and by adjusting temperature. However, certain characteristics of the ink should not be disturbed if quality lithographic printing is to result.
  • the roller hardness or durometer must be correlated with the angle " A2 " between the metering surface of the metering member and the roller surface to establish a wedge W in the area between metering surface 24 and the surface 45 of the applicator roller immediately adjacent thereto and immediately upstream from metering edge 25 to form a film of a desired thickness. It should be apparent that the same metering member will be urged deeper into a softer roller surface than it will be urged into a hard roller surface if the same force is applied to the metering member. Thus, as illustrated in FIG. 3, the angle W between metering surface 24 and the surface 45 of the applicator roller would be reduced as the durometer of the applicator roller surface is reduced.
  • the thickness of the cover 44 on the applicator roller influences metering because the spring-constant of the resilient roller is not linear as force is increased. If the roller surface is highly compressed its resilience or its ability to be deformed will be reduced. Thus, if the thickness of the cover 45 on the applicator roller is reduced the apparent hardness of the resilient cover will increase.
  • the load on the metering member should be selected to assure that metering edge 25 moves radially, if necessary, while the roller rotates.
  • the force must be sufficiently great to deflect the member 10 and to indent metering edge 25 into the roller to establish an angular relationship between metering surface 24 and the surface of the applicator roller adjacent metering edge 25 which is necessary for uniformly metering a particular ink.
  • the angle "A3" between support surface 26 and a line tangent to the surface of the applicator roller is not particularly pertinent and does not in of itself influence metering so long as the trailing edge remains indented into the resilient roller surface if the force urging support surface 26 into indented relation with the resilient roller surface is sufficiently great to prevent hydroplaning.
  • a very light force for example, one pound per inch of length of the metering member, is employed to indent metering edge 25 into the roller surface, it is necessary to then position support surface 26 substantially perpendicular to a plane which lies radially of the resilient roller surface to preclude application of a lifting force under dynamic conditions which would cause the thickness of the film of ink to increase as the press speed increases.
  • Pressure at a first metering edge created by slightly deforming the hard, durable cover, generally meters a thin, light film unless a certain inefficient pressure wedge is formed by an obtuse angle on the indented working end of the metering member.
  • the rate of depression of the hard cover by a slightly indented obtuse edge gives long life to the edge and to the roller cover.
  • ink metering member 10 when associated with applicator roller 40 accomplishes the objects of the invention here- - inbefore enumerated.

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EP82106199A 1981-07-13 1982-07-10 Vorrichtung zum Dosieren von Tinte mit einem abgestumpften Dosierelement Withdrawn EP0070484A1 (de)

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Publication number Priority date Publication date Assignee Title
US4610201A (en) * 1983-08-13 1986-09-09 Heidelberger Druckmaschinen Ag Printing unit with short inking device
EP0551797A1 (de) * 1992-01-14 1993-07-21 Maschinenfabrik Wifag Dosierleiste
US6523469B2 (en) 2000-06-08 2003-02-25 Man Roland Druckmaschinen Ag Device for metering and equalizing an ink layer on the surface of a printing machine roller

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Publication number Priority date Publication date Assignee Title
DE3714936A1 (de) * 1987-05-05 1988-12-08 Wifag Maschf Farbwerk fuer eine druckmaschine
JP2534937B2 (ja) * 1990-03-10 1996-09-18 株式会社大同機械製作所 工作機械の被加工物保持装置
JP2003154630A (ja) 2001-08-06 2003-05-27 Fuji Photo Film Co Ltd インキ供給装置及び印刷機

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2534320A (en) * 1946-05-16 1950-12-19 Champion Paper & Fibre Co Apparatus for coating paper
FR2408458A1 (fr) * 1977-03-21 1979-06-08 Dahlgren Harold Appareil et procede pour doser l'encre pour presse rotative

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2534320A (en) * 1946-05-16 1950-12-19 Champion Paper & Fibre Co Apparatus for coating paper
FR2408458A1 (fr) * 1977-03-21 1979-06-08 Dahlgren Harold Appareil et procede pour doser l'encre pour presse rotative

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4610201A (en) * 1983-08-13 1986-09-09 Heidelberger Druckmaschinen Ag Printing unit with short inking device
EP0551797A1 (de) * 1992-01-14 1993-07-21 Maschinenfabrik Wifag Dosierleiste
US6523469B2 (en) 2000-06-08 2003-02-25 Man Roland Druckmaschinen Ag Device for metering and equalizing an ink layer on the surface of a printing machine roller

Also Published As

Publication number Publication date
JPS5865663A (ja) 1983-04-19
CA1198627A (en) 1985-12-31
DE3225982A1 (de) 1983-02-03
DD202663A5 (de) 1983-09-28

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