DD202663A5 - COLOR WORKING FOR A LITHOGRAPHIC PRINTING MACHINE - Google Patents

Abstract

The invention relates to an improved inking unit of the aforementioned type. The invention provides an inking unit which enables continuous precise control of the ink film thickness and in particular avoids the formation of so-called ghost images. The invention leads to significant material and time savings. The essence of the invention resides in an inking unit comprising a single elastic surface applicator roller capable of cooperating with a lithographic printing plate under relative pressure engagement, in combination with an improved ink dosing member having a thin, controllable, uniform ink jet film on the ink jet Surface of the pressure roller forms, the ink film thickness is independent of the surface circumferential speed of the elastic roller.

Description

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Inking unit for a lithographic printing machine

Field of application of the invention;

More particularly, the invention relates to an inking unit for a lithographic printing machine, comprising an applicator roll having an elastic surface which is applied under pressure to a pressure plate, a strip-shaped dyeing dosing member, and a support means for supporting the dosing member designed in the manner of a cantilever , whose unsupported end is pressed into the elastic surface of the applicator roll, wherein upon rotation of the applicator roll of this a color excess is moved to the unsupported end of the cantilever.

Characteristic of the known technical solutions: inking units for printing plates entering the market

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have found generally contain two to four forming rollers which are in rolling engagement with a pressure plate. Each of the forming rollers is normally in rolling engagement with one or more vibrating rollers to which ink is fed through a plurality of rollers in a roller train of rollers of different diameters, the rollers being generally arranged in a pyramidal manner. Color is supplied to this compactor via a ductor roller which is to be brought into and out of oscillation motion and has a non-uniform ink film. The uneven film is formed by a flexible blade (doctor blade) which is pressed into engagement with a hard surface on a slowly rotating ink fountain roller by many ink keys.

The ink film formed on the ink fountain roller is too thick and uneven to be applied directly to a printing plate in a quality printing. These inking units, which include a plurality of rollers, are provided to reduce the ink thickness and to constantly provide a film of uniformly controllable thickness on the printing plates. However, since the "starved" in the printing ink film on each mold roller with each rotation of the mold roll is not completely refreshed, it is known to so-called. Ghosting or color accumulation on the one hand and lack of color on the other hand.

In an effort to avoid both the cost and the disadvantages of such multi-roll inking, efforts have been made to provide inking

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in which a new, fresh paint film is metered onto an elastic forming roll which has been brought into relative pressure engagement with a planographic printing plate to eliminate the rollers, eliminate the ghosting, and last but not least, the excessive accumulation or " Starvation "of color.

In a known system, there are two rollers of approximately equal diameter, which bear against each other under mutual pressure and form a gap, with the adjacent surface portions at the gap moving in the opposite direction. One of the rolls is completely cleaned by a pair of doctor blades, and the rolls are compressed together so that the local pressure at each point along the line of contact or nip is greater than a "critical pressure threshold", so that theoretically .With one of the rollers carries a color film of constant thickness over the length of the rollers, which can be applied directly to a printing plate, without having to come before or in contact with equalization rollers or come. However, since the adjacent surfaces of the rollers move in the opposite direction at the nip, and because the pressure over the length of the gap between the rollers is not uniform, the temperature at the adjacent surfaces moving in the opposite direction, As a result, there is a substantial change in temperature along the length of the rolls, and accordingly also in the color carried by the rolls. Moreover, a considerable amount of power is required to turn the rolls and increase the film thickness of the metered dye.

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Film at the nip is not very sensitive because even slight changes in the surface speed of the roller, which has been completely cleaned of paint, results in a drastic change in the ink film thickness borne by the other roller.

Ideally, a stationary metering unit for the problems known from the prior art inking units should be a solution which requires no drive in addition to that required to rotate a single forming roller. Attempts have been made to provide doctor blade blades as metering units, but these attempts have been found to be failing altogether. Doctor blades have been used successfully as ink strippers in inking units which have a roller for spreading and smoothing the paint, but such blades have been found to be unsuitable for use alone as ink dosing units for a molded surface elastic roller in a lithographic , Pressure application to be used.

Printing ink, generally speaking, is an oily, viscous substance which is highly pigmented and which may be said to be tacky so that the ink adheres as intended to the image portions of a lithographic printing plate. When the image portion of the printing plate transfers ink directly to paper or a blanket cylinder, which in turn transfers the ink to paper, small fibers, lint or fragments of coating material or the like adhere. on the surface of the plate cylinder. The plate causes

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this foreign material reaches the surface of the inking roller. When the surface of the inking roller is moved directly into the ink supply and then scraped with a conventional doctor blade for cleaning, such foreign particles tend to accumulate on the edge of the metering blade, causing the formation of a nonuniform ink film on the roller surface Episode has. For this reason, in addition to the so far random behavior of the surface of the elastic roller under dynamic conditions, no inking device has been developed or proposed which is suitable for continuously metering (dosing) a uniform film directly onto the surface of an elastic roller with a doctor blade to cause rolling engagement with a pressure plate.

It is not possible to maintain a uniform pressure between a fixed edge and the surface of an elastic roll under dynamic conditions because the respective modulus of elasticity of the elastic surface of the roll increases as the periodic load increases. The dimensions of the elastic forming roll change under dynamic conditions when the elastic surface is subjected to periodic load changes, since elastic material has a so-called "memory" and does not immediately recover to restore the original original dimensions after such an elastic surface has been subjected to compression. Furthermore, a vibration as well as a fatigue of the elastic roller surface by a substantial

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Indentation of the surface induces or creates because the elastic sheath is as it were "accumulated" as a result of the compressive load on one side of the stationary, fixed edge, and because it is under tension on the other side of the edge. Vibration of the axis of the roll relative to a stationary, fixed edge resulting from movement of the roll surface into and out of the nip in the plate cylinder need not be completely isolated from the solid nib edge.

Object of the invention:

The present invention addresses the problem of forming a continuous film of ink of the same thickness on an elastic roll surface and the directly related problem of moving the ink film into engagement with the image portion on a lithographic printing plate, the rolling compactors mentioned hereinabove, which are present in known inking, should be avoided, while continuing an excessive power requirement for dosing a thin, uniform color film to be avoided, also the problems' should be solved, which can be with a collection of lint or the like. result. Furthermore, a dosing member is to be provided which does not unduly stress an elastic roller surface and can damage it, with no or at most a harmless vibration to be transferred to the roller surface, and finally a total dosing be created with which it is possible To form a uniform film whose thickness is independent or at least practically or largely independent of the printing press speed

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Explanation of the essence of the invention:

The subject of the application is concerned with improvements to an inking unit as disclosed in U.S. Patent Application Serial No. 142,596 of April 22, 1980, which disclosure is hereby incorporated by reference in its entirety.

Such an improved inking unit as is the subject of the present patent application comprises a single applicator roll having an elastic surface which is intended, suitable and accordingly capable of cooperating under relative pressure engagement with a lithographic printing plate in combination with an improved ink dosing member which is suitable is to form a thin, controllable and uniform film of ink on the surface of a mold roll whose ink film thickness is independent of the surface peripheral speed of the elastic roller.

The surface of the roller advancing from the engagement area with the pressure plate is passed through a reservoir, i. Thus, a supply of color, so moved that an excess of color is applied to the surface of the roller or such that there arises to refresh the "exhausted" portions of the ink film after printing on the plate again. A metering member having a metering surface for a given ink viscosity is brought into relation to the elastic surface of the roller to form a wedge-shaped draw-in portion to which the excess color transports through the roller surface

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is formed to form a thin, uniform film of ink which adheres to the elastic surface of the roller.

The thin, flat or rectangular body of the dosing member is brought approximately tangential to the roll surface in position, so that the color strikes as it were a weir against the thin side or edge of the dosing. If the positioning is carried out so that the angle between the dosing member and a tangent is smaller than 30 °, the dosing member is fixed in the tangential direction and flexibly supported in the radial direction. A trapezoidal shaped metering member or portion of such metering member is formed on the thin edge of the metering member to form an optimum diometric relationship for metering ink and to separate the metered ink film from the metering member while the metering member is in the metered position Dosing member is held substantially tangential to the elastic roller surface and is supported.

The metering member is mounted so that two polished, flexible edges of the trapezoidal shaped metering section are separated by a support surface and can move radially relative to the axis of the elastically coated roller. The edges are urged toward the resilient surface of the roll under pressure to create a substantially constant metering relation relative to the roll surfaces along the entire length of the roll and circumferentially. The polished, flexible edges of the dosing are

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Accordingly, it is firmly supported in a substantially tangential direction with respect to the roll surface, and the trailing edge is oriented to deform the elastic roll surface to minimize moistening of a substantial surface portion of the dosing member downstream of the polished trailing edge and separation of paint from the dosing member to effect adjacent to the polished trailing edge. Accordingly, the rear surface of the trapezoidal metered metering portion of the metering member is shaped such that ink on the indented elastic roller surface does not separate from the roller surface and build up on the rear surface of the metering member as they are compressed Situation which results from the fact that the relevant surface portion has passed or passed the flexible, polished rear edge of the dosing.

Accordingly, a primary object of the present invention is to provide an inking system for printing presses capable of continuously precisely controlling the ink film thickness provided on a lithographic printing plate in consideration of the above-mentioned objects In order to avoid in this way in particular the formation of so-called. Geisterbilder and a change in the color or color density of the printed images, which ultimately have a considerable waste of time and materials and corresponding costs result. A further rounding off of the task for the subject of the application is for the competent expert

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due to the above and following description, taking into account the other documents easily recognizable.

Preferred embodiments of the present invention are described in the subclaims.

EXAMPLES

The invention is explained below with reference to exemplary embodiments with reference to a drawing. It shows:

1 shows a cross section through a lithographic printing machine.

Fig. 2 is an enlarged fragmentary cross sectional view showing the relation of the metering member relative to a resilient coated forming roll in a static condition and under dynamic operating conditions;

3 shows an enlarged, partial cross-section of the trapezoidally shaped metering section at the working end of the dosing member;

Fig. 4 shows the mutual relation of different surfaces of the dosing each other;

Fig. 5 is a curve diagram showing in principle that when a force the metering member in relative pressure engagement or depression with a

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Roll surface brings, and when this force is increased, a minimum ink film thickness is achieved, with a certain angular relationship between the dosing member and the roll surface;

Fig. 6 is a curve-like view similar to Fig. 5, showing a family of curves for different angles of the metering surface relative to a radial line to the roller;

Fig. 7 is a graph showing the change in color density transversely across a printed sheet in response to a change in the force with which the edge of a metering member is forced into relative pressure engagement with an elastic roller surface; ,

Fig. 8 is a graph showing the change in the positioning of an edge of the metering member when an elastically coated roller rotates at a constant speed and also at varying speeds;

Fig. 9 is a graph showing that the ink film thickness is independent of the printing press speed; and

10 is a somewhat schematized or simplified

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folded illustration showing the color density on a printed sheet.

Identical and equivalent parts are provided in the individual figures or figures with the same reference numerals.

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The inking unit generally designated 1 in Figs. 1 and 2 of the drawing has spaced side frames 2 fixed to side frames 3 of a printing machine having a conventional plate cylinder P, a blanket cylinder B and a printing cylinder I for printing on a web W or on sheet material, especially on paper.

A support means 5 is provided to adjustably secure a dosing member 10 between the side frames 2 and to position the dosing member 10 relative to an applicator roll 40 provided with an elastic coating. The opposed ends of the applicator roll 40 are rotatably mounted on the side frames 2 in suitable bearings. The applicator roll 40 is driven by any suitable drive means such as a chain 4 which drives a sprocket on the plate cylinder with a sprocket on a coupling (not shown) at one end of the chain Application roller 40 drivingly connects. The surface speed of the applicator roll 40 is preferably substantially equal to the surface velocity of the plate cylinder P.

Side stops 6 are secured to the support means 5 and are pressed into sealing engagement with opposite ends of the applicator roll 40, and the dosing member 10 forms a color reservoir or ink supply R from which ink is metered onto the surface of the applicator roll 40. One or more ink fountain rollers 8a and 8b are in rolling engagement with the paint on the surface of the applicator roll 40 to remove any irregularities on the surface.

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Smooth surface, which may occur in the ink film before the ink film from the surface of the applicator roll 40 to the dampening unit D and to the surface of a pressure plate P 'of the plate cylinder P is supported. The ink fountain rollers 8a and 8b are in rolling engagement with the ink on the surface of the applicator roll 40 and not only smooth out surface irregularities, but also change a finished finish of the metered ink film into a smooth nearly matt finish to prevent the ink fountain roller To condition paint film for proper moistening and for application to an image portion of a printing plate.

It can be seen that when the surface of the applicator roll 40 moves away from the surface of the printing plate P ¹ , the surface is again smoothed and conditioned by a dyeing and wetting liquid supply roll 8c before being immersed in ink and having an excess of color in the ink Color supply R is applied to it.

When the color system is used for lithographic printing, fountain solution is first applied to the paint on the surface of the applicator roll 40 and then onto the printing plate P ¹ on the plate cylinder P. Means are provided for drawing wet liquid from the surface of the applicator roll 40 evaporate or the like. is to prevent an accumulation of superfluous wetness liquid in the color pool R. As shown in Fig. 1 of the drawing, a hollow, perforated or slotted tube 9 extends transversely between the side frames 2 and is provided with openings

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through which dried compressed air is passed to direct a stream of dry air to the surface of the applicator roll 40. At least one end of the tube 9 is or the like via a hose line. connected to a suitable air source, not shown.

Incidentally, when wet liquid is used in the ink fountain of the present invention, a greater than normal ratio of alcohol to water may be provided to print with less water and to accelerate vaporization of the wet liquid remaining on the applicator roll 40 when it moves away from the printing plate P " ¹ ". Thus, the dampening solution could contain more than the normal 5 to 25% alcohol to ensure rapid evacuation of the dampening solution from the applicator roll as it moves between the plate and the paint dosing member. The alcohol, one or more rollers 8c and the air, all these measures can do their part to remove excess wetness after printing and to ensure a new distribution.

As will be explained in more detail below, in order to provide accurate control of the viscosity, the paint contained in the ink supply R and, if desired, to change the ink viscosity with the ink supply R are flexible pipes 7 or the like. connected to give a liquid such as water at a controlled temperature and in a controlled extent in the one end of a line 5 'of the support means 5 and from the other end of the line 5' again

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lead out.

For a high-speed printing, the physical properties of the ink film 130 formed between the metering member 10 and the elastic jacket 44 of the roller 40 and the color present in the ink fountain R can be further controlled by temperature control of a liquid passing through the oscillating rollers 8a / 8b or 8c and / or a line in the core 42 of the roller 40 flows. It has been found that a large flow rate only produces a small temperature change along the length of a roll, and that heat can be eliminated by monitoring and controlling the outlet temperature and controlling the color temperature so that the physical properties of the film produced are maintained throughout the length of a production run substantially constant.

Accordingly, by cooling or heating liquid flowing through support 5 and / or roller core 42 and / or rocker rollers 8a, 8b or 8c, the ink viscosity at and before nip N to be defined below is controlled to be a constant desired Color film for the purpose of proper pressing on the plate P ¹ maintain.

The dosing member

A preferred embodiment of the Farbdosiergliedes is shown in Figs. 3 and 4.

In particular, from Fig. 4 it can be seen that the Farbdosierglied 10 a smooth, polished, precision machined precision

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Dosing edge 25 which is formed at the junction or penetration of a metering surface 24 and a support surface 26.

The metering edge 25 preferably extends in length over a distance within a range of 10 to 80 inches (about 25 to 200 cm) depending on the printing machine width, and is formed by the penetration of the polished surfaces 24 and 26. The polished surfaces 24 and 26 meet at an obtuse angle to each other, so form a kind of wedge with an included angle A ₁ , which is approximately 120 or greater.

The metering edge 25 is preferably made of a relatively hard metallic material having a Rockwell hardness of C 48 to 50 or more. It is important, that the polished metering edge 25, the metering surface 24, the support surface 26, the trailing edge 28b of the support surface 26 and the adjoining, hereinafter also referred to as "third surface" rear surface 28a of the dosing member are wear-resistant, as they be pressed into the elastic surface 45 of the forming roll 40 during normal operating conditions.

The dosing member 10 is preferably elastic, i. It consists of flexible, metallic material with a modulus of elasticity of about 30 χ 10 psi or less, to provide the property that one with respect to the metering edge 25 when rotating the forming roller 40 in view of the comparable movement as a "pickup" (compared with a Record player).

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A dosing member 10 has been produced with good results from a strip of stainless spring steel with sheared edges, which is commercially available from, for example, Sandvik Steel, Inc., Benton Harbor, Michigan / USA, and is designated Sandvik 7 C 27 Mo. 2 is sold.

The strip of stainless steel was chosen particularly for its hardness, flatness, elasticity, grain structure and smooth surface finish to ensure high wear resistance and good fatigue properties. The stainless steel strip had a thickness of 0.070 inches (about 1.78 mm) and a width of about 5.3 inches (about 135 mm). The material strip was heat treated and had a glossy polished surface finish, an extra accurate thickness and normal strength. The width tolerance was - 0.016 inches (about 0.4 mm) and the thickness tolerance was - 0.00181 inches (about 0.46 mm). The stainless steel strip was corrosion resistant in the presence of air, water and most of the organic acids in solution at room temperature. The tensile strength was about 249,000 psi corresponding to a Rockwell C 49 hardness.

Originally, the edge at the junction of surfaces 22 and 26 had serrated notches giving a corresponding jagged edge contour. To form a straight precision edge and a continuous line across the extension, the metering member 10, the surfaces 24 and 26 were ground at a predetermined obtuse angle and then ground with a fine grain stone,

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as will be explained in more detail below, as a first step in forming the polished metering edge 25. The strip was then clamped in a special holder. The surface 24 of the strip was superfinished at a predetermined angle by hand using a fine grain grindstone and then polished by hand with a 600 grit abrasive paper.

As a last step, the stainless steel strip was placed on a flat horizontal surface. The surface 2 6 was then finished by hand with a super finish, with a gritstone with fine grain and then hand polished with a 600 grit sandpaper.

If there is a sharpened edge on the dosing member during superfinishing and polishing of surfaces 24 and 26, this should be removed with leather or a polishing agent. When this sharpened "feathered" or ridged edge has been removed, a smooth, continuous, uniform, defect free edge is formed on the strip. Accordingly, in polishing the "bevel" edge 25, the "sharpness" of the edge may be altered somewhat to form a non-cutting, non-film-piercing edge. This manufacturing process provides a fine, continuous, smooth, straight, polished, sophisticated, uniform, superfinished edge 25 with minimal surface irregularities. There should be no small notches or protrusions in the edge. The edge 25 formed by the polished surfaces 24 and 26 is a

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extremely fine edge that has been polished / to create a supreme quality finish and to make the texture as perfect as possible. The surfaces 24 and 26 are preferably finished so that RMS 4 is not exceeded. The term "super-finish" as used hereafter refers to a surface that is ground and polished so that the surface tips are removed and flat, flat surfaces are formed, but still have the smallest "valleys" or reservoirs, to accept and carry the lubricant color.

The edge 25 is finished to a surface finish which approximates that of the edge of a razor blade. It will be appreciated, however, that the obtuse angle A- between the surfaces 24 and 26 is significantly greater than the corresponding angle of a razor blade, and that accordingly an obtuse, blunt, non-cutting and non-penetrating edge is formed. In effect, the surface 24 merges, as it were, "merging" into the surface 2 6 via the edge 25, forming on each side adjacent to the metering edge 25 a continuous, polished surface.

Not only must the material used to form the edge 25 be tough enough and capable of providing a blunt, fine, polished, uninterrupted edge, but the material must also be tight yet over the length of the metering edge 25 be flexible. The edge 25 should be quite flexible in the longitudinal direction, so that the edge 25 when pressed under pressure into the elastic surface of

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Application roller 40 is bent or bent accordingly and gives way under the influence of the surface of the roller 40, so that the edge 25 and the surface of the roller 40 can adapt to each other / and thus formed a substantially uniform depressed portion over the length of the roller 40 becomes. As will be explained in more detail below, the elastic jacket 44 of the roll 40 has a thickness of the order of 3/8 to 5/8 inch (about 9.5 to 15.9 mm), preferably about 1/2 inch ( about 12.7 mm), and an elasticity of about 40 to 70 Shore A hardness, preferably 60 Shore A hardness units. This "biasing" of the edge 25 to provide a corresponding fit to the surface of the roller 40 should be possible without unduly depressing the surface of the roller when in dynamic running conditions.

The edge 25 of the metering member 10 should be arranged so that it is elastically pressed in the direction of the surface of the applicator roll 40, and that it is freely movable over its entire length in the radial direction of the applicator roll 40. The edge 25 must also be firmly supported in a substantially tangential direction to the applicator roll surface.

An ideal support for the metering edge 25 is a flexible lever arm (= cantilever), which carries the edge 25 and on the one hand provides the required flexibility and on the other hand for the required strength or firm support. For example, while the edge 25 may be part of a separate, substantially trapezoidal, cross-sectioned element that is operatively connected to the lever arm, a preferred embodiment is to constrain the edge 25 of the trapezoidal element.

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shaped portion 10 on the Arm.selbst form, so that both are an integral unit. To accomplish this, the lever must be flexible in two directions, along the length of the edge 25 and also along the width of the strip, i. the length of the arm.

The ink dosing member shown in Fig. 4 of the drawing wherein the edge 25 is formed on the unsupported end portion 10 "of the cantilever has a substantially rectangular cross-section formed by front and rear side surfaces 22 and 22 ', respectively. an upper side 28 and a lower side 29. The support surface 26 lies substantially in the plane of the lower side 29 when the lever arm or cantilever is in a non-bent state

24 and the support surface 26 penetrate each other to form an obtuse angle A ₁ and intersect at a vertex 25, which is essentially a straight line.

The lever or cantilever arm, which is the obtuse-angled edge

25 may be made of, for example, a thin, flexible elongated strip of stainless steel or a corresponding strip-shaped material, as described above, and may have a thickness of, for example, 0.070 inches (about 1.78 inches) mm) and a width of 5.3 inches (eg, about 135 mm) or less. The width of the lever or the length of the material strip is preferably within the range between 25 cm to about 2 m and the lever is flexibly supported over the length of the edge 25, as well as this over the length of the

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Lever arm is the case. For example, the modulus of elasticity of the lever arm may be 29χ10 psi and is known to provide a measure of the stiffness of the material, i. for its resistance to deformation. When this value is combined with the moment of inertia I, the EI factor gives the stiffness of the lever arm.

The specific dimensions and characteristics of the metering member 10 have been exemplified, and it should be understood that these dimensions, characteristics, and assembly conditions may, of course, be changed for specific conditions. Accordingly, preferred dimensioning ranges have been specified here.

The dosing member 10 also has a recess in the bottom 29 of the strip of material from which the dosing member 10 is formed.

The portion of the strip of material that is to be polished to form a polished edge 25 is covered and the metal material is removed adjacent thereto by mechanical or chemical grinding to thereby remove a portion of the metal without creating stress may cause a deformation of the strip.

The third surface 28a adjacent to the support surface 26 is smoothed by hand sanding so as to remove about 0.003 inch (about 0.076 mm) of rough surface material. The third surface 28a can then be replaced with 600-

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(grit) abrasive paper are honed to form a very smooth surface finish on the surface 28a. The trailing edge 28b is accordingly formed as set forth above with reference to the edge 25.

If the thickness, i. the distance between the surfaces 26 and 28 of the strip of material is 0.070 inches (about 1.78 mm), the depth of the recess 27 is preferably greater than 0.020 inches (about -0.5 mm), for example 0.035 inches (about ca. 0.89 mm) so that the material thickness between the surface 28 'forming the top of the recess 27 and the top surface 28 is approximately 0.035 inches (approximately 0.89 mm).

The third surface 28a intersects the polished support surface 26 at an angle A ¹ in a range between 30 and 90 ° (the latter as shown). The upper portion of the metering surface 24 of the metering member 10 may extend to the top 28 or be angled at an angle to form the front side surface 22 (as shown).

The metering surface 24 may accordingly only be a relatively small chamfer of the original front side surface 22. The obtuse angle A, not only provides a dosing member with a blunt, obtuse-angled edge which is not "fragile", but is primarily formed at a particular angle or configuration to meter a particular color film thickness for a particular viscosity paint and color intensity, and around the

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Film without immediate change in the direction of the roll surface to dose and without too much indentation of the roll shell, which would have a rapid wear of the dosing and / or the roll shell result.

In the embodiment of the dosing member 10 shown in the drawing, the polished metering surface 24 extends from the polished edge 25 over a distance upwards, which is approximately equal to the depth of the recess 27 or larger and the surface 22 intersects or penetrates. It is readily apparent that the polished support surface 26 supports the polished edges 25 and 28b. If the surfaces 24 and 28a are parallel, the surface 26 can be refi ned without changing the stress characteristics of the polished edge 25 of the dosing member 10.

The surfaces 26, 24 and 28a and accordingly also the edges 25 and 28b are easily renewable. By slightly re-finishing the support surface 26, both edges can be "sharpened" again at the same time or the surfaces 24 and 26 can also be sharpened again. After considerable use, a small radius or a curvature can arise at the edge 25 and change the metering properties. In order to avoid having to change the entire dosing member, the regrinding and finishing by hand described above can be repeated several times before the entire dosing member has to be replaced. Normally, 1/1000 to 3/1000 inch of each surface to be machined is removed, with the extent of post-processing depending on the extent of wear

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depends to re-deliver or "sharpen" the edges 25 and 28a.

To refine the surfaces 24 and 26, a special holder can be used to prevent damage to the dosing. Such a holder should not only hold the dosing member, but also provide guide surfaces for fine grinding treatment by means of a doctor blade or the treatments with abrasive paper to ensure that only a minimal amount of material is removed, and that the angle A and the edges 25 and 28 are maintained.

The angle A ¹ should be sufficiently large to allow a paint film existing on the surface of the roller 40 to separate from the support surface 26 without accumulating paint on both the support surface and the third surface 28a, with the result in that there then dewdrops accumulated paint and causes a non-uniform pressure.

The applicator roll

The applicator roll 40 has a hollow, solid, tubular metal core 42 and a resilient, nonabsorbent shell 44 secured to the core 42, the shell 44 having a smooth, uniformly textured and resilient exterior surface 45. Although the coating or jacket 44 of the applicator roll 40 is elastically relatively fixed, for example, in one

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Range between 40 and 70 Shore A.

The jacket 44 of the applicator roll 40 preferably consists of an elastic urethane, polyurethane, rubber or a rubber-like or rubber-like material which is attached to the metallic core 42. In a preferred embodiment, shell 4 4 is made from Buna nitrile rubber, which provides a natural surface with microscopic pores to absorb and retain color therein and to enable the metering of a thin color film suitable for lithographic printing applications.

The jacket 44 of the applicator roll 40 should have high strength, high tear and abrasion resistance and be resistant to oil, solutions and chemicals. The sheath 44 should also have a relatively low indentation resistance, good recovery and uniform ink receptivity. For example, a suitable sheath may be urethane or rubber to provide an elastic coating of preferably about 60 Shore Α hardness.

For example, a suitable urethane shell can be made from a set, pre-catalyzed material available from Arnco of South Georgia, California / USA under the trademark "Catapol". The material is preheated at 160F for about 5 hours, then poured into a mold around the roll core, and finally heated at 280 F for about 8 1/2 hours, and finally cooled prior to grinding and polishing.

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A suitable rubber coating can be obtained, for example, from Mid-America-Roller Company of Arlington, Texas, USA, under the designation "Buna-Nitrile", which is conventionally applied over the core and prior to polishing with a high Speed-Schleifzeug or -mittel is treated. ,

After an elastic sheath 44 of urethane or rubber.o.dgl. has been formed, the roller may have a whitened or "glossy" outer skin, which is removed by grinding. After grinding with a 120 grit abrasive tool, the surface of the resilient sheath 44, when made of urethane, can be treated with 180 grit abrasive paper to form a surface of uniform smoothness on the surface 45 of the resilient sheath 44. However, when the elastic sheath is rubber, after grinding with a 120 grit tool, the rubber may be treated with 400 grit abrasive paper to provide a velvety smooth uniformly textured surface free of "orange peel" structure ¹¹ or other non-uniformity is.

Microscopic reservoirs in which ink is held help to ensure that a continuous, unbroken ink film remains on the surface 4 5 of the applicator roll 40.

Surface scratches, sanding lines and other surface irregularities should be removed so that the surface roughness - whether it be

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when the sheath is one of urethane or rubber - after treatment with abrasive paper, it does not exceed 30 RMS. As will be explained in detail below, the adhesion forces between the color molecules and the molecules of the surface 45 of the sheath 44 must have the cohesive force between the color molecules to allow shearing of the color and to form a controlled, continuous, unbroken color film on the surface 45 of the applicator roll 40.

It is known that it is extremely difficult, if not impossible, to make the roll 40 so that the surface 4 5 is perfectly round in the circumferential direction and also remains so, furthermore that it is perfectly straight in the longitudinal direction, and finally that it is precisely concentric with the axis of the roll core 42. The straightness or waviness of the surface 45 of the roll 40 can be achieved economically with a tolerance of about 0.002 inches (about 0.05 mm) along the length of the roll The radial eccentricity can be made within a tolerance of about 0.0015 inches (about 0.038 mm).

A Shore Α hardness test is generally used to measure the hardness of an elastic roll shell, with penetration resistance measured at a constant temperature of about 76 F with the roll shell stationary. The hardness of an elastic surface under dynamic conditions deviates considerably from the hardness measured in the hardness test under static conditions. The spring constant of a

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elastic material increases as slightly as the deformation increases.

As the stress frequency of an elastic member increases, the dynamic modulus increases, with the result that the sheath appears to be made of a harder, stiffer material. However, a cyclic cycling of an elastic material results in the generation of internal heat which raises the temperature and results in a reduction in hardness and, consequently, in the elastic modulus of the elastic jacket.

Since the surface 45 of the roller 44 is preferably in pressure engagement with the surface of a plate cylinder, the plate cylinder has a longitudinally extending gap, which cyclic or periodic stress results in unevenly sized heat generation in the circumferential direction of the surface 45 Such temperature differences on the surface 45 can result in a significant change in the radial distance from the axis of the roll 40 to points of the surface 45, since the coefficient of thermal expansion of elastomeric materials used to form elastic roll shells is several times higher than that Thermal expansion coefficient of steel, for example.

As stated, the roller 40 may be different in diameter than the plate cylinder P, without thereby printing a color film 130 on

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a web W or sheet is adversely affected because the metering member 10 produces a continuous ribbon on the surface 45 of the applicator roll 40 / independent of the previous indentation and independent of the temperature variations in the roll shell 44.

The applicator roll 40 should not have the same diameter as the plate cylinder P, because in such a case, even the slightest defect, a hole, crack or the like. on the surface of the applicator roll 40 would repeat at the same location of the plate when both are driven at the same peripheral speed and have the same diameter. Such a repetition can lead to adverse effects, in particular when printing a lithographic plate on the non-BiId sections. Such an outline or the like. can namely on a printed sheet or the like. appear as a color in a non-image section. Accordingly, if such an irregularity occurs in an image portion, too much color may appear accordingly. Accordingly, it is most appropriate not to say that the surface of the applicator roll 40 does not repeat with the plate surface of the plate cylinder. It has been observed that if such repetition does not occur, said irregularities will not affect a lithographic plate in a non-image portion, even if such an irregularity is relatively strong.

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The support device

The supporting device 5 for supporting the lever arm-shaped dosing member 10 according to FIGS. 1 and 2 has an elongated support beam 50 which has a ground and really flat surface 52 on its one side and an area 54 which is angled relative to the flat surface 52 forming a shoulder 50 which extends along the support beam 50. Bearings 56 extend outwardly from the opposite ends of the support bracket 50 and are rotatably supported in self-aligning bushings 57 (not shown) in bearing blocks 60 which have outwardly extending projections 58 adjacent the opposite ends.

In each of the projections 58 there is formed an elongate slot through which anchoring screws 52 'for securing the bearing blocks 60 to the inking unit side frame 2 extend.

As can be seen from Fig. 1, four lifting screws 64 extend through threaded holes in the projections 58 on the bearing blocks 60 and are engaged with a surface 65 of the inking unit side frame 2 to move the support bracket 50 in the vertical direction.

Transverse adjustment screws 66 extend through threaded bores in outwardly extending lugs of the inking unit side frame 2 and engage end faces 66 'of the projections 58.

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From the foregoing, it can already be seen that the position of the bearing blocks 60 in the vertical and horizontal directions is adjustable, as can be seen from Fig., In order to adjust the support bracket 50 relative to the axis C of the roller 40 can.

An arm 70 is bolted or otherwise attached to the end of the bearing 56 on the support bracket 50 and urged by a piston rod 71 of a fluid pressure actuated cylinder 72 against one end of a stopper bolt 74 screwed to an arm 75 or otherwise connected to the bearing block 60. It will be appreciated that the support bracket 50 is rotatable relative to the bearing block by adjusting the position of the end of the stop screw 74 relative to the arm 75.

A pressure regulator R "is installed to adjust the inlet pressure in the cylinder 52 to be sufficiently large to hold the arm 70. firmly against the screw 74 on all impressions of the edge 25 into the surface 45 of the shell 44.

The metering member 10 is secured to the flat surface 52 of the support bracket 50 by screws 76 which extend through spaced apertures in a clamping member 78 and oversized openings which extend adjacent the trailing edge through the lever arm. The screws 76 are screwed into threaded bores of the support bracket 50. The screws 76 and the clamping member 78 work together so that the dosing member 10 evenly on the

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Support beam 50 is fixed or supported by this, so that the edge 25 has a uniform spring characteristic over its length.

In the embodiment of the device according to FIG. 1, the stop screw 74 is remotely controlled by a DC motor 80, which is fastened to the arm 75 by a support bracket 81. Between the motor 80 and the screw 74, a reduction gear is arranged to continue to control the rotational speed of the screw 74. Between the screw 7 4 and the output shaft of the motor 80 is connected to both splined coupling or the like. 76 'arranged. A suitable motor 80 is commercially available, for example, from the Globe Industries Division of TRW, Inc., Dayton, Ohio / USA.

Connecting lines 82 and 84 extend between the motor 80 and a motor control unit 85, the control unit 85 being of conventional construction and having a DC power source and a three-position switch.

The engine position control unit 85 has a digital indicator 86 for indicating the position of a rotary potentiometer, not shown, at the end of the stopper bolt 74 which cooperates with the arm 7O to provide a visual indication of the position of the support bracket 50 for the dosing member 10 create. The engine control unit 85 is attached to the side frame 3 of the printing press in the embodiment shown in the drawing. An additional or

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however, further motor control unit 85 is preferably located adjacent the discharge end of the printing press or on a control console so that the position of the dosing member 10 can be remotely adjusted when printed sheets are inspected to adjust the color density across the sheet as required ,

The inking unit side frames 2 are pivotally attached to the printing machine side frames 3 by means of a shaft, adjacent to opposite sides of the printing press. A fluid actuable disengagement cylinder 92 is pivotally attached to protrusions 93 secured to the side frames 3 of the printing press, and has a piston rod 94 pivotally connected to a boss 95 formed by welding or otherwise with the inking units Side frame 2 is connected. A one-stop single screw 96 is screwed into a lug which is connected to the pressure side of the machine frame 3 and so arranged that it is provided with the inking unit-side frames 2 engage when the pressure between the surface of the application roller 40 and the printing plate P ¹ is achieved properly. An off-stop single screw 98 is threaded into a lug connected to the printing machine side frame 3 by welding or otherwise, and engages the inking unit side frame 2 when the piston rod 9 of the release cylinder 92 is extended while maintaining the surface 45 of the applicator roll 40 separates from the surface of the printing plate P ¹ .

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As set forth above, the side boundaries 6 are pressed into sealing engagement with the opposite ends of the applicator roll 40 and define the opposite ends of the ink supply R. A color retention wall 100 is in sealing engagement with the surface 45 of the applicator roll 40. as shown in Figs. 1 and 2 of the drawing, and their opposite ends are fixed to the side edges 6. The lower edge 102 of the color retaining wall 100 is preferably at a slight distance from the surface 22 of the Farbdosiergliedes 10th

The color retaining wall 100 defines the input side of the ink supply R. The output or outlet side of the ink supply R is limited by a component 105 which is fastened by means of screws 106 on the support bracket 50. A lower seal 108 adjacent the component 105 is disposed adjacent the top 28 of the metering member 10 to prevent ink flow from the ink supply R, including the top 28 of the metering member 10, to form a stagnation region where paint ceases to flow , Since lithographic ink is thixotropic, the ink viscosity is significantly reduced when ink is in motion compared to the viscosity of ink at rest.

As shown in FIG. 1 of the drawing, a component 110, also referred to as a stirrer for the sake of simplicity, is attached to the ink retaining wall 100 to act on the paint in the ink fountain R. The stirrer 110 is commercial

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for example, available from the company Baldwin-Gegenheimer, Stamford, Connecticut / USA, and has a sprocket-pinion drive, not shown, which extends longitudinally over the upper portion of the ink supply R and carries a mixing head, which via a chain of a motor with constant speed is driven. As the mixing head approaches a side boundary 6 located at the end of the applicator roll 40, it reverses one direction of motion and moves to the other end of the ink supply R. The stirrer 110 turns in color to shear or shear transversely to exercise the color and to prevent viscosity irregularities along the color supply.

Commissioning and operation

The operation and operation of the device described above is as follows:

The dosing member 10 is aligned by means of two bolts or pins 51 which are pressed into the support bracket 50 and extend through precisely arranged aligned holes in the dosing member 10. The dosing member 10 is secured to the surface 52 of the support bracket 50 by the screws 76. The pins 51 in the support bracket 50 extend through holes in the dosing member 10 and ensure a uniform projection of the dosing member 10 over its length safely and accordingly also a uniform bending and stress or force applied to the edge 25. The anchoring screws 52 are first dissolved to a

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Agility of the bearing block 60 relative to the inking unit side frame 2 to allow.

The lifting bolts 64 are provided to align the surface 52 parallel to the axis C and to adjust the angular relationship between the support surface 26 of the (actual, lower) metering member 10 "relative to a tangent to a radial line of the applicator roll 40 passing through the edge 25 to be able to.

The transverse adjustment screws 66 are provided to move the bearing block 60 relative to the applicator roll 40 and to permit alignment of the edge 25 of the metering member 10 relative to the surface 45 of the elastic shell 44 of the applicator roll 40.

After the edge 25 of the dosing member 10 is aligned with the surface 45 of the applicator roll 40 and the angular relationship between the surface 26 and a tangential line to the applicator roll 40 has been established, the anchoring screws 42 'are tightened, which the bearing blocks 60 fixed to the side frame second fasten.

As can be seen from FIGS. 1 and 3, the edge 25 of the dosing member 10 now passes through the surface 45 of the jacket 44 of the roller 40 at a point P "approximately in the 11 o'clock position, ie in the 9-12 o'clock position. Quadrants, assuming that 0 and 12 o'clock are at the top of the applicator roll and that the designation is similar to that of a clock face

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selects. The ink reservoir R is accordingly formed as shown and, of course, due to gravity, causes ink to be present at the edge 25 of the dosing member 10, thereby providing complete fusion of paint on the front of the dosing member 10 on the surface 45 of the shell 44 The edge 25 is now brought into "kiss contact" with the surface 45 of the applicator roll 40. An amount of ink greater than that necessary for continuous coloring of the plate P ¹ on the plate cylinder P is required, is provided by the ink supply R of the surface of the applicator roll 40, which approaches the metering surface 24 of the dosing member 10.

After the edge 25 has been brought in "kiss contact ¹¹ with the surface 45, the stopper screws 74 are rotated, whereby the support bracket 50 is rotated from the position shown in solid lines in Fig. 2 in the position shown there in dotted lines.

This leads to a bending of the cantilever and the flexible, polished edge 25 is brought into pressure engagement with the elastic surface of the applicator roll 40 and adapts to this accordingly. Rotation of the roller 40 now continuously moves ink from the ink supply R into contact with the metering surface 24 and the edge 25. In this way, ink is adequately sheared onto the surface 45 to a color film 130 / which can be varied in thickness , like this

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set out below in detail.

Assuming that the edge 25 is firmly supported at one end of a cantilever arm, the function is for the bendline

Y = F (2L ³ - 3L ² x + x ³ ) 6EI.

In a prototype, the distance between the shoulder 55 and the metering edge 25 of the metering member 10, which would correspond to the unsupported end of the cantilever, was 1.625 inches (about 41.3 mm), the distance between the surfaces 28 and 28 'was 0.035 4 inches (about 0.89 mm) and a static load of 25 ppi width (about 4.46 k / cm) was applied to the edge 25. The support width S was 0.15 inches (about 3.8 mm). The modulus of elasticity E of the dosing member 10 was about 30 χ 10 psi.

The moment of inertia I of a rectangular area is

12

where b equals the base length of the rectangular area and h equals the height of the rectangular area. The moment of inertia I of the dosing member 10 with a thickness of 0.03 5 inch wi: the cantilever calculated.

Thickness of 0.035 inches becomes 3.5 x 10 inches per inch width

At the unsupported end of the cantilever is χ 0 and the deflection is Y.

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FL ³

3EI.

Accordingly, it was calculated that the deflection of the unsupported end of the cantilever would be about 0.31 inch (about 7.87 mm) with a load of 25 ppi width exerted on the edge 25. Accordingly, it was concluded that the spring constant for the cantilever would be 0.012 inch deflection per pound force (0.4536 kp) on edge 25, or 81 pounds per inch deflection on 1 inch width of edge 25.

It should be noted that the calculation of the bending line, as stated above, can only be an approximation of the calculation of the bend of the edge 25, the dosing member 10 is not very well firmly clamped or clamped to the shoulder 55 of the support beam Is 50, and since the 0.03 5 inch recess does not extend all the way to the shoulder. However, it is certainly obvious that the edge 25 is acted upon elastically in the radial direction of the applicator roll 40.

The deflection or distance traveled by the edge 25 of the metering member 10 was actually measured to be 0.14 inches (about 3.56 mm) in the above example when an average static force of 25 ppi was applied to the edge 25. A division of the force of 25 ppi by the deflection of the metering member 10 gives approximately 178 ppi flex. The calculated from the actual bending of the elastic dosing member 10 spring constant differs from the above approximately calculated spring constant.

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The differences between the approximate and actually measured spring constant have already been predicted.

The wide support width S of 0.15 inches (about 3.81 mm) was chosen to provide an adequate support surface corresponding to the large-25 pound force acting on the support surface 26 of the dosing member 10 and Figs the shell 44 of the applicator roll 40 in the N ¹ pressed portion on the color film formed on the dosing 25 to create a pressure in the region N ¹ , which is sufficiently large to the entire surface 26 and both edges 25 and 28 b in the Surface 45 of the shell 44 of the applicator roll 40 depress. Static indentation was measured to be about 0.06 inches (about 1.52 mm), but instantaneously changed to 0.04 inches (about 1.02 mm) upon rotation of a 60-durometer applicator roll. which had a sheath of 0.5 inch (about 12.7 mm) thickness. It has accordingly been concluded that for a desired bending of the edge 25 on the cantilever portion of the dosing member a certain force is required, and that for this force a certain support surface is required, which creates a pressure which is sufficiently large to a particular roller shell to a depress sufficiently large amount, and between the roll surface and the metering at the first edge of the dosing member 10 a wedge ο.dgl. to meter a given color of known viscosity to a desired film thickness as the film leaves the rear (second) edge of the support surface of the metering member. Generally it can be said that low

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Edge bends require low forces to obtain the low bending, and then a support can be made by means of a correspondingly small support surface in order to achieve a sufficiently large pressure for the indentation in a certain shell to a desired extent. Large bends require correspondingly large forces in order to obtain the desired large bend, but a correspondingly large support surface must be present in order to achieve the same pressure and the same indentation in one and the same coat. Accordingly, Fig. 3 shows both, namely a large support surface width S and a small width S ¹ S is greater than t, namely approximately 2 t, while S ^{1 is} equal to or less than t, namely approximately equal to t in the illustrated embodiment. Satisfactory results have been obtained with values S between t and 2 T. Relatively large edge bends are also desirable to provide a system which, while responsive to changes in the position of the stop screw 74, does not respond to it too sensitively.

As will be explained in more detail below, the combined distance that the edge 25 is bent plus the distance that the edge 25 is pressed into the roll surface 45 is preferably substantially greater than the maximum spacing between points on the surface Roll surface 45 and edge 25 when the surface and edge are in "kiss contact". For example, unevenness or manufacturing inaccuracies of the roll surface 45 and slight waviness of the edge 25 may easily increase to a maximum

.24 16 1 7

Deviation of 0.002 inch (ca, 0.05 mm) lead, so that the surface 45 and the edge 25 are not compliant with each other when they first touch. If the edge 25 is bent 0.16 inches (about 4 mm) and pressed into the surface 45 by 0.04 inches (about 1 mm) under dynamic conditions, the initial deviation of 0.02 inches would be only 1 % of the combined distance of 0.20 inches (about 5.1 mm). Since the edge 25 and the jacket 44 are elastic, they behave flexibly and can adapt to each other. After such adjustment, the pressure along the touch strip N is substantially constant, and the effect on the color film is insignificant with respect to the small differences.

This combined bending and indentation distance under dynamic conditions is one hundred times the original deviation so that the maximum error after pressing the edge 25 against the surface 45 is only 1%. Accordingly, pressure and indentation changes in the area N become irrelevant. This has the consequence of maintaining a color film thickness that is more than acceptable to printers for uniformity of color density. Printers are known to call a controller very good if the color density does not vary more than -5% over the printed sheet.

rather than - 5% over the surface of a

As shown in Fig. 3, the edge 25 of the dosing member 10 is so pressed into the surface of the applicator roll 40, that the elastic material forms as it were bead-like, upstream

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to the surface 24 a small bead or a wave in the shell 4 4 is formed, while downstream of the edge 25 in the jacket 44 a kind of groove or a channel 27 'is formed. The section in front of the surface 24 forms a wedge through which paint is pulled. The wedge is bounded on one side by a portion of the surface 24 and the edge 25 and on the other by a portion of the surface 45, probably between a small portion of the bead 120 and the portion of the surface 45 immediately adjacent the polished edge 25 When the cantilever arm allows the flexible edge 25 to follow the contour of the applicator roll, the wedge automatically moves slightly radially relative to the axis C of the applicator roll 40. Because the wedge cooperates by cooperating with each other oppositely biased flexible edge 25 and elastic surface 45 of the applicator roll 40 is formed, this movement is desirable if a constant pressure relationship to the ink extruded through the orifice is to be maintained. The surface of the applicator roll 40 constantly changes its contour as the roll rotates due to its 'elastic memory', temperature variations, and variations in the dynamic modulus of elasticity, as discussed previously above. Accordingly, it is important that the edge 25 can automatically move radially and deform flexibly in the longitudinal direction to accommodate these contour changes.

The elastic edge 25 of the dosing member 10 and the elastic jacket 44 of the roller 40 can at a

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certain view also be considered as two opposing springs, each having a spring constant K ₁ and K ₉ , in which case the common or Gesamtfederkonstante calculated to

K = ^K 1 ^{x K} 2

This common spring constant K is less than each of the spring constants K ₁ and K ₂ . Table 1 below and the resulting calculations demonstrate the above finding that the total spring constant K is less than the single spring constants K- and K ₂ respectively. Further, the table shows that the original 0.002 inch deviation or error was only resulting in a final pressure difference of about 1% of the static or dynamic pressure.

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Table I

Data part F = force C 28.6 A = range (In ² ) P = F / A pressure (I / In ² ) D = bend (in) K = F / D ram. Spring bed. Constant Dosing member M 25 Sheath C order 28.6 roller M .15 C 167 M .14 C 178 _{ static Sheath M order 25 roller M .15 C 167 M .06 I C 417 (for 0.15 in.) Dosing member M .15 C 191 M .16 C 178. dynamic M .15 C 191 M .04 I C 715 (for 0.15 in.)

(im =

* / IN _f

178 + 417

^{E (%)} static ^{= (} · ⁰⁰²⁾

(167) (.15)

100 =

dynamic = ⁽¹⁷⁸ >

^{= 143}

178 + 71.5

dynamic

1 43)

x 100 =

(191) (.15)

M = measured C = calculated

accordingly, E (%) = + 1/2 2

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Accordingly, the actual metering 10 ", ie the working end of the metering device 10, which is bounded by the surfaces 22, 28a, 26 and the line 28" forms a rectangular cross-section, the metering 24 and the edges 25 and 28b, and may be spring loaded by any other means which has the same function as the cantilever portion of the dosing member 10, ie the working end over its entire length in the radial direction elastically and in the tangential direction firmly or relentlessly supported. When the surface 24 is formed on the rectangular portion, the working end of the dosing member 10, as can be seen in Fig. 4, forms a trapezoidal portion 10 "as it were.

It should be noted that the paint carried by the surface 45 of the applicator roll 40 abuts or impinges on the metering surface 24 (acting as a kind of weir, as it were), and that the surface has a portion of turbulent flow adjacent the bead 120 on the elastic Roll surface forms. It follows that, although the edge 25 is pressed down elastically, as can be seen in Fig. 3, the metering surface 24 is formed and positioned, and that the edge 25 in a sufficiently resiliently biased against the roller 40 presses to a change of Films 130, to effect by hydrodynamic forces that are exerted on the dosing member 10 by the color. This condition is further assisted by positioning the polished edge 25,. so that it is closer to the central axis C of the applicator roll or this itself than any other

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Point of the support surface 26 of the dosing member 10. The blunt, obtuse polished edge 25 preferably deforms the applicator roll elastic mantle to form a metering wedge angle W between faces 24 and 120 to form a precisely controlled thickness paint film having approximately a pressure profile such as this is shown in Fig. 3, where the maximum pressure is located on the front dosing.

The surface 28a of the metering member 10 is positioned immediately downstream of the support surface 26 so that the metered ink film is only in contact with the metering member 10 along the support surface 26 and that the ink film 130 is immediately removed from the metering member at the edge 28b to prevent color from moving along the surface 28a, which would lead to an accumulation of color, dripping, and eventually random flow which causes uniformity of the color film. Would destroy 130.

The underside of the metering member 10 is formed so that the surface 28a at the "heel" or edge 28b of the polished surface 26 and the at least partially enclosed recess portion 27 relative to the direction of movement of the ink film .130 at an angle, so that the Roller surface 44 can not deform back to a position in which the color film 130, the surface 28 'contacts and collects on the surface 28 a and builds up.

Accordingly, at. The embodiment of FIG. 3, the dosing member 10 is formed and arranged so that the

η ι ι Uf j η η η ... n η ιλ μ «»

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Ink film 130 separates immediately from the dosing member 10 when the roll shell moves to the relaxed, not depressed position.

Referring to Fig. 3, it should be noted that the edge 25 is illustrated as being impressed by a dimension d in the surface 45 of the applicator roll 40 whose original radius R has a surface velocity V, a cladding thickness T and a hardness D. ,

The metering member 10 shown in Fig. 4 has a support surface width S, a thickness t and a recess height r, which (at this point) a Kraghebelhöhe of (t ./. R) leaves. The distance L refers to the cantilever and the dimension 1 denotes the length of the recess. The metering surface 24 is set at an angle B (T ./. H). The angle A- denotes the total included obtuse angle between the surfaces 24 and 26 and is 90 ° + B.

Referring back to Fig. 3, it should be noted that the angle A _{3 represents} the small angle of attack of the support surface 26 to a parallel line to a tangent of the roll radius R determined by the indentation measured by the point P ". Den.Schnittpunkt on the radius R of the surface 45 from a radial line and a tangent to the roller. The angle A ₃ is preferably 0 ° or slightly larger to ensure that the edge 25 is depressed by an amount equal to or greater than any other point of the support surface 26. The gap N is a measure of the color

24161 7. 8

between the support surface 26 of the metering member 10 and the depressed roller surface in the zone between the edges 25 and 28b, which is represented by the support width S. In fact, the thickness of the nip N is substantially equal to the thickness of the ink film 130 formed behind the edge 28b on the roller surface 45, which varies in accordance with the parameters discussed above. A_ is the angle between the metering surface 24 and a radial line passing through the point P 2 '. It applies

A- D J. J \

The angle W is the wedge or entrance angle between the surface 24 and a tangent to an imaginary circle or curve with a surface 120 moving toward the edge 25.

It is generally believed that the pressure at the edge 25 and the angle W substantially determine the thickness of the ink film 130 at a given liquid viscosity u.

The resulting pressure effect of such a dosing member 10, which is properly used in conjunction with an elastically coated applicator roll 40, is that the surface 45 of the roll mantle 44 produces a pressure profile which is significantly different from those in the prior art metering apparatus arise, which interact with elastic on its outside applicator rollers. In contrast to the prior art, where the pressure gradually increases to a maximum at a trailing edge and drops rapidly to zero, like this one

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conventional blade wipers for coating paper, etc., the invention disclosed herein, as can be seen in Fig. 3, causes a more or less sudden increase in pressure on the roll shell because the obtuse first edge 25 is in the incoming , presses the rotating roller, wherein the pressure reaches a peak or a maximum P "and then drops rapidly slightly when the roller has passed the edge 25 and passes under the support surface 26 of the metering device 10, and the pressure then quickly again to 0 decreases as the roller or roller surface leaves the trailing edge 28b of the dosing member 10. In a somewhat different way, it can be said that the maximum pressure P _{M of} the dosing member 10 according to the invention is achieved at the obtuse, first or front dosing edge 25 of the dosing member 10, and not at the second edge of the dosing member, ie the trailing edge 28 b this is the case with known paper coatings. In cases where in the prior art in Farbdosiereinrichtungen also a pressure increase at a first edge may be achieved, it has not been recognized that in addition an important second edge must be provided, as provided here according to the invention, in the elastic surface of the roller is pressed in order to prevent that the dosing effects generated by the front dosing edge are not destroyed afterwards.

Furthermore, it is important in positioning and supporting the two mentioned edges over their lengths, as provided here, that in the tangential direction, a firm support of the edges, and that the support in the radial direction

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is flexible, these two features cooperating and together to provide automatic dosing consistency and uniformity as the roller rotates, and even as the speed of rotation varies.

During testing of the apparatus described above, it has been found that when the force which the edge 25 initially engages in pressure engagement relative to the surface 45 decreases, the thickness of the film 130 decreases to a minimum thickness and then upon further growth of the pressure, the film 130 grows again while remaining evenly.

From Fig. 5 it can be seen that this surprising phenomenon occurs when the force acting on the edge 25 of the cantilever-type metering device 10 increases in the direction of the surface of the roller 40. If a small force per linear unit length of edge 25 was provided to bring edge 25 into compressive engagement with surface 45, the color density decreased. However, at this low load, the color density was not uniform across the length of the roller 40. When the force was increased, the paint film thickness on the roller was reduced until some increase in load along the length of the edge 25 per length unit was achieved. The ink film thickness then began to increase as the force applied to the polished edge 25 toward the center axis C of the roller 40 was increased. In other words, as the force grew, the film thickness was initially decreased and then began to increase when the film thickness increased

54 -

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Load was further increased. However, the color density became extremely uniform in the transverse direction along the length of the roller 40 and in circumferential direction about it when the applied load exerted an average static force of 25 ppi on the edge 25 and the support surface 26.

The area 26 was 0.15 inches (about 3.81 mm) wide. The thickness of the roll mantle was 0.50 inches (about 12.7 mm) and the hardness was 60 Shore A-. The resulting indentation was 0.04 inch (about 1.02 mm) and the roller radius was 5-1 / 8 inch (about 13 cm, see Table II, Example I).

This phenomenon, where at a pressure threshold, the ink film thickness suddenly begins to decrease and then begins to increase as the force on the edge 25 becomes higher, was observed when the edge 25 is the lower leading edge of a cantilever metering member. Fig. 3 shows such a dosing member 10 in such a depressed relation to the surface 45 of the roller 40 in a position in which the edge bending stress, the pressure (which determines the indentation) and, accordingly, the ink film thickness (which determines the color) are substantially constant are.

Referring to FIG. 5, it can be seen that the ink film thickness 130 varies as a function of indentation of the polished edge 25 into the resilient surface 45 of the shell 44 of the applicator roll 40. As has already been described above, as the indentation increases, the thickness of the ink film 130 rapidly decreases to a minimum and then begins again.

24 16 17

to grow. Imperfections on the surfaces of the metering device 10 and the applicator roll 40 are readily apparent in the metered ink film 130 until the polished edge 25 is depressed to a point where the change in the initial edge-to-roller relation along the length of the edge 25 is small, for example, less than -5% compared to the total bend. At this point, as the polished edge 25 is further bent and pressed into the surface 45 of the applicator roll 40, the color film becomes more uniform and uniform and remains substantially uniform.

It has been observed that the minimum ink film thickness according to the minimum in the graph of FIG. 5 is determined primarily by the pressure at the edge 25 and by the angle of the metering surface 24 relative to the roll surface 120, which is shown in FIG certain color viscosity is indicated with W.

With reference to Figures 3 and 4 of the drawings, it should be noted that the metering surface 24 is defined by the angles B and A-, so that the metering surface 24 extends counterclockwise in the direction of the bead 120, as shown in FIG. 3 is recognizable. The minimum film thickness according to the curve in Fig. 5 is determined for a specific roller hardness and thickness, meter member support surface width, load (= bias) and ink viscosity. Accordingly, a change in the obtuse angle A _{1 of} the metering member 10 and the positioning angle A "between the metering surface 24 and a roller radius a set of curves of FIG. 5, as shown in Fig. 6.

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From the foregoing, with simultaneous reference to FIG. 6, it can be seen that an angle A ₂ can be selected and, accordingly, that the obtuse angle A _{2 can} be determined so that the desired film falls well within the loading range of a uniform film 130 produced without considerable indentation and without acute training of the angle A-, which produces heat and a rapid destruction of the metering edge 25 and / or the roller surface has 4 5 result.

It has also been observed that the thickness of the film 130 can be changed within certain limits by changing the ink viscosity of the ink in the ink supply R. Accordingly, by controlling the temperature of water or other liquid flowing through the tubes 7 and the conduit 5 'in the support beam 50, the ink viscosity in the ink reservoir R can be changed to change the color density effecting the coloring or set. The viscosity or the flow property of the ink can also be changed by means such as so-called reducers and / or extenders for the purpose of changing the color.

It can be seen from Fig. 6 that the least obtainable ink thickness as a result of a particular angular relationship between the metering surface 24 and a radius of the roller 40 may be that ink completely disappears from the surface 45 of the roller 40 before the dot, where the film thickness begins to rise again. Accordingly, to prevent rapid wear on the surface of the roller 40 and / or the edge 25 of the metering member 10,

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should be an angle A-. as shown, i. e.g. 30 ° to produce uniformity while at the same time providing minimum and maximum film thickness without excessive pressure which would result in considerable indentation and rapid wear.

It is a curve and thus an angle A- and in a similar manner in angle B are chosen, with which to achieve the minimum desired color, at about the same time the minimum available film is achieved. For example, angles A ₂ = 15 ° and A "= would not reach this parameter. When using inks for lithographic offset printing on coated material, the generally recommended or desired color density for cyan is 1.25, for magenta 1.30, black 1.60 and for yellow 0.90. The area should carry about - 15 dj.

-15 dense points or a total of 30 dense points

Printing ink is generally an oily, viscous substance which is highly pigmented and can be said to be sticky so that the ink adheres properly to the printing sections of the printing plate as intended. Paint, which is generally used for printing newspapers, has a viscosity in the range of 50 to 80 poise. Paint, which is commonly used for printing on printing presses, as well as color for offset printing on webs, has a viscosity of the order of about 150 to 200 poise. Color, which is used in the lithographic offset printing of sheets, generally has a viscosity of about 250 to

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300 poise.

If different viscosities are present, the curves denoted by 0 °, 15 °, 30 °, 45 ° / 60 ° etc. in FIG. 6 no longer apply as shown. Accordingly, Fig. Applies in the manner shown only for specific design parameters of the roller and the metering member and the flow behavior or the strength of a particular color used. For a more fluid color than they are used in lithographic sheetfed printing, so for example, a color, as in the black newspaper printing in printing machines or the like. For example, if the angle required to produce an acceptable color density for direct lithographic printing on newsprint or the like would be used. in the order of 60 ° instead of 30 °, as this has been chosen above. For extremely viscous, very solid colors, one would choose smaller angles A _{2 in} order to achieve the desired print results. Accordingly, one can easily find optimal angles for A- and accordingly B, since A ₃ should be 0 or slightly larger after the design parameters for the applicator roll 40 and metering member 10 are fixed for particular films and required viscosities , allowing one produce the paint to be produced without significant indentation, which would premature jacket and edge defects on the applicator roll or on the dosing would result. It should always the largest possible angle A ₁ and B, that is used so the dullest angle of the dosing member 10 in order to achieve the desired results.

Due to the design of the dosing adjacent

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to the ink supply R, the ink flow in the ink supply to the metering member is turbulent, with the result that lint or other contaminants are generally rejected by a high pressure portion immediately adjacent the leading edge of the metering member. Such lint or the like. are retained in the turbulent vortex of the paint reservoir, thereby minimizing the delivery of donor particles to the metering edge of the metering member. Color that flows due to the movement of the surface of the elastic roller towards the first polished edge of the metering member causes a nearly instantaneous increase in pressure, and the turbulent flow becomes laminar immediately adjacent the first polished edge. The ink is sheared off as it moves through a wedge between the resilient surface of the roller and the metering surface of the metering member adjacent to the first polished edge.

The polished support surface 26 and the edges 25 and 28b of the metering member 10 are urged toward the resilient surface 45 of the applicator roll 40 by a force sufficiently large to extend the roller surface 45 along the length of the edges 25, 28b and along the length Press the roller surface 45. The required indentation depends on the desired color thickness, the modulus of elasticity of the elastic roll mantle 44, the thickness of the elastic roll mantle 44, the temperature, strength, adhesion and viscosity of the paint and other properties relating to the flow properties of the paint, the texturing of the paint roll

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surface, the state and, where appropriate, the arrangement of the leading edge of the dosing member, the support surface width, the dosing member dosing angle, the position of the support relative to a line tangential to the roller, the pressure between the application roller and the adjacent plate Conditioning of the paint before and after application to the plate, as well as the solution present in the ink to be dispensed and any added solution to be dispensed The polished edges of the dosing member are pressed slightly into the surface of the elastic roller, for example 1/30 inch a roller having a surface hardness of 60 Shore A and a shell thickness of about 1/2 inch (about 12.7 mm) As the roller rotates, the polished edges of the metering member move relative to the axis C of the roller 40, to maintain a state of equilibrium so that the edges 25, 28b automatically relaad radially along their length move to the axis G of the roll surface and in the circumferential direction to this move, although the roll surface 45 is not ideal round and not free of light waves.

Fig. 7 schematically shows the above-discussed phenomenon, which is that the uniformity of color density on a printed sheet increases as the force with which the edge 25 is pressed under elastic pressure into the surface 45 of the roll 40 increases ,

As has been described above in the comments relating to Fig. 10 of the drawings, the color density printed on a sheet was compared with that of Figs

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Surface of the bow measured points distributed. Maximum and minimum color density readings were registered. Sheets were selected which had been printed with different biasing force applied to the edge 25 of the metering member 10 to vary the color density throughout the sheet.

It can be seen that the difference in color density between the maximum and the minimum over the entire sheet decreased as the force with which the polished edge was pressed into relative pressure engagement with the elastic roll shell 44 of the roll 40 increased this by the lengths of the lines D-, D ", D-. and D. has been indicated in Fig. 7.

It is believed that the cantilevered member 10 was flexed when a force applied to the edge 25 to bring it into relative compressive pressure engagement with the surface 45 and when that force had been increased. The elastic sheath 44 of the roll 40 was deformed and also the edges 25 and 28b were slightly deformed along their length, so that the edge 25 and the surface 45 of the roll 40 were matched in close proximity to each other, although the edge 25 and the surface 45 of the roller were not ideally compliant in a "kiss-touch" position. Accordingly, the deformation of the metering member 10 contributes to the deflection of the edge 25 along its length and the engagement of the jacket 44 all contribute to the proper ink film thickness and uniformity

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To obtain color density across the surface of a printed sheet.

With reference to Figures 5 and 7 of the drawing, it should be noted that the ink film thickness drops to a minimum and then begins to grow again as the force which causes the edge 25 to press relative to the roller surface 45 under pressure engagement, grows. Accordingly, the same color film thickness is obtained at two different points on the curve. However, as indicated by the different lengths of lines D ₂ and D ₄ in Fig. 7 of the drawing, the change in color density at the two curve points is different.

Referring to Figure 8 of the drawings, it should be noted that a dial gauge has been mounted on the support bracket 50 and brought into engagement with the top surface 28 adjacent the metering surface 24 of the metering member 10. When the applicator roll 40 was rotated, a total of 0.002 inch (about 0.05 mm) dial indicator was observed. This showed that the runout of the radius of the surface 45 of the roller 40 was 0.001 inch (about 0.025 mm), and that the edge 25 of the metering member 10 was 0.0025 inches (about 0.05 inches) on each rotation of the roller 40 mm). When the surface peripheral speed of the roller 40 was increased, the travel of the edge 25 remained substantially equal at different surface peripheral speeds of the roller 40. The overall deflection of the metering member 10 increased somewhat when the surface area of the roller 10 was increased. Circumferential speed of the roller 40 has been increased. It was also observed

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that, unless the pressure on the disengagement cylinder 9 2 has decreased, the edge 25 has moved to the axis C by approximately 0.20 inches when the applicator roll 40 has stopped. Accordingly, the polished edge 25 of the metering member 10 moves automatically relative to the axis C of the applicator roll 40 with each movement of the applicator roll 40 as a result of speed changes and ovality of the applicator roll. To compress the roll shell 44 by the edges 25, 28b and the support surface 26 of To prevent dosing member 10 and a resulting damage to the roll shell 44 and thereby caused stripes on the printed sheets, the system should be designed so that the pressure in the cylinder 72 is reduced or completely degraded when the roller 40 is stopped.

When starting the air pressure should be adjusted back to the normal working pressure against the stop screw 44. In this way, the maximum indentation of the edge 25 in the Walzenoberf- surface 45 only takes place when the roller rotates below the edge 25 with a color lubricant film N therebetween. If the pressure is not reduced when stopping, the edge 24 presses the roller surface 45 almost twice as much as under running conditions.

From Fig. 9 of the drawing, it can be seen that the ink film thickness remained substantially constant over a wide range of speeds, and accordingly is substantially independent of the surface speed of the applicator roll 40.

As already described above, moves

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the edge 25 of the metering member 10 automatically in the radial direction when the applicator roll 40 rotates. However, the dosing member 10 is positioned so that the metering surface 24 and the polished edge 25 are firmly supported in the tangential direction. It will be appreciated that the force exerted on the metering surface 24, which is generated with color due to impingement is directed both in the tangential and in the radial direction of the application roller 40, and that ( '"., The force against the surface 22 of the The metering member 10 is angularly positioned so that it is very stiff in a substantially tangential direction to the applicator roll 40. This indicates that during operation, the metering member 10 is only substantially tangentially directed in a dynamic position, the angle A _{3 of} the support surface 26 is substantially zero or may be slightly larger than the pressure wedge angle W, which arises immediately before the edge 25 of the metering member 10 and acts against the roller surface 120 and the Dösierflache 24 because the surface 24 is relatively small, can not generate a sufficiently large force to the edge 25 of the roll surface 45 or the roll surface e 45 to lift off the edge 25 and to result in a change of the film thickness as the speed increases.

While it is necessary for the metering member 10 to be configured so that it can press the edge in the radial direction, on the other hand the metering member 10 must have a sufficiently large thickness to form a recess r and a cantilever bead thickness T ./. r with a related

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sensitive metering surface 24 and a polished edge. The metering member 10 should not be too thin because, when a compressive force is exerted in the plane of a thin plate, it will tend to bulge and warp, like this in the same Way in a long, thin axially loaded stem is the case. The color density printed on a sheet was measured using a "SOS 40" digital reflectance densitometer available from COSA Corporation, Garland., Texas, USA. The color density readings in the longitudinal and transverse directions of the printed sheet are shown with respect to yellow ink in Fig. 10 of the drawings. It can be seen that both the measured color density in the transverse direction and in the longitudinal direction can each be described as being very accurate. Other inks such as magenta, cyan and black were measured with the same good measurement results.

The data shown schematically in Fig. 10 show that a very uniform ink film has been metered onto the surface 45 of the applicator roll 40 with the dosing member 10.

It has been found that the drive power required to drive a printing press with an inking unit according to the invention as described above is not significantly different from the drive power required to drive a printing press equipped with conventional inking units, and that in most Cases is lower. As has been explained above, but is exploited in color "ghost"

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on the surface 4 5 of the applicator roll 40, which moves from the plate P 'to the input side of the ink reservoir R, completely supplemented with fresh new color and the printing plate P' is offered a new metered ink film with each rotation of the applicator roll 40. In this way a "starvation" of color or the emergence of so-called ghost images was eliminated. Furthermore, the dosing member 10 described above and below due to its construction, arrangement and support capable of dosing a film which is sufficiently thin and sufficiently uniform for coloring a printing plate without critical components wear out quickly, with a on or , Multi-color printing of the highest quality is to be practiced. The color density can be changed immediately by only the position of the stop screw 74 is changed in terms of settings, which is possible by remote control.

When properly formed and arranged, the dosing member 10 further causes lint or other foreign particles in the ink to be kept away from the wedge formed between the surface of the dosing member 10 and the surface 21 of the application roller 40. The metering surface 24 and the surface 22 form a barrier above the edge 24, against which excess ink strikes the applicator roller 40 as it were, thereby forming a turbulent section, as described above. Since the high pressure section is formed just prior to the movement of the paint past the polished edge 25, lint and other foreign particles are normally removed from this section.

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hold when in the paint supply R a low pressure path or section is present. The color reservoir R is preferably under atmospheric pressure. Even light foreign particles are taken up in the center of the vortex, which is formed in this low pressure section.

It should again be noted that the provision of the steep, substantially radial surface 22 prevents hydrokinetic or hydrodynamic forces that can create a hydraulic pressure wedge that lifts the polished edge 25 and. Accordingly, the thickness of the ink film 130 would change as the surface speed of the roller 40 changes. The edge 25 is thus hydrostatically supported by color, which is supported by the roll surface 45.

Any tendency of the metering member 10 to move away from the roller 40, or vice versa, is quickly and automatically overcome by counteracting elastic return forces acting against each other when both, i. the roll shell 44 and the dosing member 10 are under mutual elastic bias, as described above.

Various factors affect the ink film thickness that is metered onto the surface 45 of the applicator roll 40. These factors include: the front angle, the angle A ₁ between the metering surface 24 and the support surface 26; the angle A ~ between the metering surface 24 and a radial line; the state of the metering edge 25; the width or depth S of the support surface 26; the viscosity of the paint; the hardness of having one

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elastic coating 44 provided applicator roll 45; the thickness of the shell 44 of the applicator roll 40; and the load or force that is impressed / to bring the metering edge 25 into pressing relative pressure engagement with the shell 44 of the applicator roll 44.

The rigidity of the working end 10 'of the metering member 10 affects the uniformity. As previously described, the metering edge 25 must be deformable throughout the length of the applicator roll 40 to accommodate manufacturing inaccuracies of the roll surface 45 and to produce uniformity across the width.

Experimental results show that the ink film 130 has a thickness response to: (1) an increase in the indentation of the metering edge 25 into the shell 44 of the applicator roll 40; (2) a reduction in the portion of the support surface 26; (3) an increase in the force urging the metering edge 25 toward the axis C of the applicator roll 40; (4) a reduction in the hardness of the shell 44 of the applicator roll 40; (5) an increase in the radius of curvature of the metering edge 25; (6) an increase in the thickness of the jacket 44 of the applicator roll 40; and (7) an increase in the angle A2 between the metering surface 24 and a line R extending radially of the applicator roll 40. Also of influence: an increase in the viscosity of the paint contained in the reservoir R ¹ ; a reduction in the temperature of the paint contained in the reservoir R ¹ ; and an increase in the roughness of the surface 45 of the applicator roll 40 also results in an increase in the thickness of the ink film 130.

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It can be seen from the above that an adjustment of any one of the aforementioned seven influencing factors results in a change in the angle W, as shown in Fig. 3 of the drawings. It has been found that an adjustment for the depression of the metering edge 25 and an adjustment for the angle Ay by rotating the metering surface 24 about the metering edge 25 to change the angle A ₃ or by installing a dosing member 10 with a different angle A- gives the printer adequate color film thickness control. In an experiment in which a low viscosity ink was used and a metering member 10 was provided at an angle A of 160 ° with a hardness of the roll shell of 40 hardness units, the ink film 130 was too thick. The dosing member 10 was replaced by a dosing member 10 with an angle A- of 150 ° and the ink film 130 was immediately very satisfactory.

In another attempt, the color film 130 was too thick for a color to print on sheets, in which attempt a metering member 10 having an angle A of 130 at a durometer hardness of 30 hardness units was used. This roller was replaced with a roller having a jacket of 60 hardness units, and the ink film 130 was then too thin. The dosing member with an angle A of 1 20 ° was then replaced by a dosing member 10 which has an angle A of 130 ° and the ink film was then on the roller 40 with a jacket 44 a hardness of 60 hardness units most satisfactory.

.- 70 -

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When a dosing member 10 was tried at an angle A of 90 ° in cooperation with a roller 40 of a jacket having 60 hardness units, the ink film 130 was much too thin for the lithographic printing of sheets used in the printing ink used.

The above-enumerated influencing factors which influence the metering of color must be correlated, that is to say associated with one another, in order to provide a thinly dosed color film which is suitable for use in a lithographic printing plate. As will be explained in more detail below in connection with various specific examples of the relative allocation of the working end 10 'of the metering member 10 relative to the surface 45 of the applicator roll 40, one or more of the above influencing factors can be changed to change the ink film thickness or set.

In order to clearly understand the working and functioning of the dosing member 10, it is necessary to clearly delimit or define some designations. The metering surface 24 influences the metering of color of different viscosities and a change in the angular relationship of the metering surface 24 relative to the surface 45 of the applicator roll 40 change the ink film thickness. The main reason that the metering surface 24 significantly affects the ink film thickness is that the metering surface 24 intersects the support surface 26 at apex and is not significantly rounded. The thickness of the ink film is primarily due to the relative allocation of the metering 24 and the metering edge 25 relative to

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the surface 4 5 of the applicator roll 40 determined.

As will be explained in detail later, the support surface 26 does not significantly affect the thickness of the ink film 130 formed on the applicator roll 40. Experimental results show that, within certain limits, the angular relationship of the support surface 26 relative to the radial line "R does not in itself alter the ink film thickness." Also, the trailing edge 28b does not appear to affect the film thickness Support surface 26, however, must intersect at an apex so that the dosing member 10 is almost abruptly separated from the surface 45 of the roller 40, so that no color accumulates on the surface 28 a and leads to the phenomena, as described earlier in individual are described.

The angular relationship between the metering surface 24 and the support surface 26 and the orientation of the metering surface 24 and the support surface 26 relative to the surface 45 of the applicator roll 40 are critical. As already described above, there is a first consideration in the selection of the angle A between the metering surface 24 and the support surface 26 in the viscosity of the ink to be metered. From Example II it can be seen that a dosing member 10 has been selected at an angle of 150 between the metering surface 24 and the support surface 26 to meter printing machine ink, a very low viscosity paint whose toughness or flow properties are considered "water-like" designate

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could. Lithographic ink has a higher viscosity than ink used in printing presses, and it should be noted that in the example in I and III, the angle A- between the metering surface 24 and the support surface 26 was significantly less than the angle A-. the dosing member, as it has been used for dosing printing machine ink.

In the example of Figs. 1 to III, the metering edge 25 was formed to have a highly polished precision surface, as described above.

The width S of the support surface 26 does not in itself control the thickness of the ink film 130 formed on the applicator roll 40. However, the width S of the support surface 26 is selected so that the desired depression of the metering edge 25 into the elastic roller surface is realized. When a force of predetermined magnitude is applied to the dosing member 10. The force with which the metering edge 25 is brought into impressing pressure relationship with the surface of the applicator roll 40 should be sufficiently large to ensure a depression of the metering edge 25 in the elastic roller surface to allow a certain movement of the metering edge 25 radially to the roller when the latter rotates, but sufficiently large to provide uniformity and to prevent uncontrollable or uncontrollable vibration of the metering member 25 upon rotation of the roller 40. Since the indentation of the metering edge 25 primarily a function of the pressure

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is equal to the applied force divided by the size of the support surface is to realize certain parameters, the size of the support surface to choose, and then the sensitivity for the control of the device is set.

The viscosity of the paint can be adjusted slightly by the addition of chemical diluents or thickeners, and by adjusting the temperature. However, certain characteristics of the color should not be adversely affected if a lithographic quality stop is to be achieved.

The hardness of the roll must be adapted to the angle A- between the metering surface 24 of the metering member 10 and the roll surface 45 and vice versa, to create a wedge W in the area between the metering surface 24 and the surface 45 of the applicator roll 40 immediately adjacent thereto and immediately upstream of the metering edge 25 to form a film of desired thickness. It should be noted that one and the same dosing member 10 penetrates deeper into a softer roll surface than in a hard when the same force is exerted on the dosing member 10. This would, as shown in FIG. 3, the angle W between the metering surface 24 and the upper? reduce area 45 of the applicator roll 40, i. When the hardness of the surface 45 and the shell 44 of the applicator roll 40 is reduced.

The thickness of the shell 44 of the applicator roll 4O affects the dosage because the spring constant of an elastic roll is not linear when the force

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increases. As the roll surface becomes highly compressed, its compliance decreases. Thus, when the thickness of the shell 44 of the applicator roll 40 is reduced, the apparent hardness of the elastic shell 44 increases.

As already mentioned above in connection with the width S of the support surface 26, the load or bias of the metering member 10 should be chosen so as to ensure that the metering edge 25 moves radially if necessary as the roller 40 rotates , However, the force must be sufficiently large to regularly deform the dosing member 10 and press the dosing edge 25 into the roller 40 to provide an angular relationship between the dosing surface 24 and the surface 45 of the applicator roll 40 adjacent to the dosing edge 25, which is for a uniform dosage of a particular color is necessary.

The angle A ₃ between the support surface 26 and a tangent to the surface 45 of the applicator roll 40 is not particularly relevant and affects in itself the dosage hardly or not, as long as the trailing edge is pressed into the elastic surface 45 of the roller 40, and so long the force which brings the support surface 26 in pressing relation to the elastic surface 45 of the roller 40 is sufficiently large to prevent hydroplaning. If, however, a very small force, for example 1 ppi of the length of the dosing member 10 is applied to depress the metering edge 25 in the surface 45 of the roller 40, it is necessary, the support surface 26 then substantially perpendicular to a plane

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Positioning, which extends radially to the elastic surface of the roller 40, to preclude that it can come under dynamic conditions during running to a lifting force, which would cause the ink film thickness increases as the speed increases.

The following examples are given to illustrate specific application examples of the invention described herein using different lithographic inks with different viscosities.

The following values have been constant in the examples below:

L - 1.625 inch (Ca. 41 3 mm) 1 - ι inch (Ca. 25 , 4 mm) A ₃ B 0 ° t = 0.070 inch (Ca. 1, 78 mm) r - 0.035 inch (Ca. 0 89 mm) H = 0.02 inch (Ca. O, 51 mm) H = 0.05 inch (Ca. 1, 27 mm) and r = 0.035 inch (Ca. 0 89 mm).

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EXAMPLE I

Lithographic sheet printing ink (offset)

dates

colour Process - Magenta & Cyan paper Mead Offset Enamel - 70% plate Tri-Metal - Metalgamma blanket Reeves # 714 Compressible press Harris LUM - 2 / c speed 2000 - 6000 IPH. roll width 38 " Angle B 40 ° Angle A- 130 ° Angle A_ about 40 ° S 0.1 50 A ¹ 60 ° T 1/2 "(Buna N Rubber) D 60 Shore A d 12:04 " R 5-1 / 8 " color density 1.20 - 1.40 Ink reservoir solution 60 ° F - acid with 25% alcohol Stripes - F.R. to the plate 1/2 "- 5/8" Plate cylinder diameter 10 "

Speed ratio between applicator roller and plate cylinder

1: 1

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EXAMPLE

Printing machine ink (litho direct)

dates

colour

paper

plate

blanket

press

Speed (V) roll width

Angle B

Angle A ₁

Angle A ₂

A ¹

Color-Intensive Color Solution Strip - F.R. to plate plate cylinder diameter

Speed ratio between applicator roller and plate cylinder

Black Newsprint Western Front Page-Wipe-On N / A Goss Universal 300 - 900 FPM 36 "60 ° 150 ° Approx. 0.090" 90 ° 3/8 "(Urethane) 40 Shore A Unknown 3-1 / 2" 1 .10 - 1 .

70 ° F - alkaline (no alcohol) 1/2 "13-1 / 2"

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EXAMPLE 3

Lithographic web offset printing ink (test stand)

colour Process cyan paper Ν / Α plate Ν / Α blanket N / A press Ν / Α Speed (V) 100 - 1200 FPM roll width 18 " Angle B 45 ° Angle A ₁ 135 ° Angle A ₂ about 45 ° S 0,1 25 * ' A ¹ 90 ° T 1/2 "(Buna N) D 60 Shore A d Unknown R 4 ' color density Movie gigs set to appropriate value for the fs set web printing Ink reservoir solution N / A Stripes - F.R. to the plate N / A P let cylinders through a ser N / A

Speed ratio between applicator roller and plate cylinder

N / A

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When the working end 10 'of the metering member 10 is supported by a cantilever arm, as described and described above, to provide a resilient radial force and a non-elastic / tangential force, uniformity is a relatively high force and a resulting bending of the dosing member 10 relative to the roll surface 45. However, a large force penetrates excessively strong in an elastic roll shell, in particular in a relatively soft shell, if not a sufficiently large support surface 26 between the two edges 25, 28b of the dosing member 10 is present to the pressure and thus the depression of the roll shell to minimize. Harder roller shells are therefore recommended, especially as they are also more durable. The pressure at the first edge of the metering member, that is, at the metering edge 25, which is produced by relatively slight deformation of the hard, durable shell leads, in general, to a thin, light metered film, unless a certain ineffective pressure wedge is formed by an obtuse angle at the depressed working end 10 'of the dosing member 10. The degree of indentation of the hard shell by a relatively low depressed, blunt edge leads to a long life of the edge and the roll shell

It will be appreciated from the foregoing that the paint dosing member 10, when associated with an applicator roll 40, accomplishes the objects and objectives of the present invention as set forth above.

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Incidentally, it goes without saying that the embodiments described above with reference to the drawings represent just examples, and that other, further embodiments of the invention are possible without departing from the scope of the present invention.

Claims (2)

Invention claim: An inking unit for a lithographic printing machine, comprising a drivable driven by a drive applicator roll with an elastic surface, which bears under pressure on a pressure plate, a strip-shaped ink dosing, and a support means for supporting the formed in the manner of a cantilever dosing member whose unsupported end is pressed in the elastic surface of the applicator roll, wherein upon rotation of the applicator roll of this an excess of color is moved to the non-mounted end of the cantilever, characterized in that at the non-mounted end (10 ') of the cantilever formed as a dosing member (10) a metering section (10 '') is provided which has a metering surface (24) »a support surface (26) and a rear third surface (28a), wherein the metering surface (24) and the support surface (26) at an obtuse angle (A .) and intersect each other to form a dosing edge (24) at a vertex and wherein the rearward third surface (28a) and the support surface (26) intersect each other to form a trailing edge (28b) at a vertex; in that the support means (50) positions the support surface (26) of the dosing member (10) substantially parallel to a tangent to the resilient surface (45) of the applicator roll (40) passing through the nip between the dosing member (10) and the resilient surface (45) of the applicator roll (40) extends, wherein the dosing of the dosing member -V iaJPR1933 * O83448 241617 (10) is disposed at an angle of less than 30 ° to the tangent, the rearward third surface (28a) is arranged such that the angle between the tangent and the rearward third surface (28a) is greater than 30 °, and the metering surface (26) is arranged so that the angle between the tangent and the metering surface (24) is less than 90 °; and that the dosing member (10) and the surface (45) of the applicator roll (40) are arranged so that by the movement of the applicator roll (40) an excess amount of paint against the located at the non-mounted end of the cantilever dosing surface (24) of the dosing (40). 10) is moved, and the color (of the dosed ink film (130)) at the trailing edge (28b) of the dosing member (10) separates therefrom. 2. inking unit according to item 1, characterized in that the dosing member (10) consists of metal in a manner known per se » 3 inking unit for a lithographic printing plate with a drivable driven by a drive applicator roll with elastic surface, which rests under pressure on the pressure plate and a dosing, characterized in that the dosing (10,10 ') a dosing (24), a support surface ( 26) and a rearward third surface (28a) which intersect each other and form an obtuse metering edge (25) and a trailing edge (28b); that the applicator roll (40) is rotated so that on its surface (45) located color against the metering surface (24) of the dosing member (10, 10 ') is moved; that fcfittel are provided, -V -ί3 - 24 1617 8 by means of which the support surface (26) is to be positioned substantially tangentially to and in engagement with the surface (45) of the applicator roll (40) such that the angle between the metering surface (24) and a radial axis to the roller (40) extending line in the range between 10 ° and 70, the metering surface (24) is set to the radial line in the direction of the approaching Yfelzenoberflache, and the metering edge (25) is formed so as to ensure that when changing the angle between the metering surface (24) and the radial line there is a change in the thickness of the ink film (130) adjacent the metering edge (25) on the surface (45) of the applicator roll; and means are provided by means of which the metering edge (25) and the trailing edge (28b) are to be brought into relative pressure engagement with the elastic surface (45) of the applicator roll (40). " An inking unit comprising a device for metering a liquid and for controlling a given, thin, uniform liquid film of predetermined viscosity from a supply of an excess amount of liquid to a liquid carrier, characterized by an endless, rotatable, liquid-carrying member (40) having a smooth, solid, resilient compliant outer surface (45) which is textured and capable of supporting a continuous fluid film (130); an elongate metering member (10, 10 ') with substantially -A- a »-rj WI / \ J trapezoidal cross-section which is flexible over its length, the trapezoidal shape being formed by two substantially parallel surfaces, namely an upper surface and a lower surface, and one surface forming an upper surface and the other a smooth, hard supporting surface (26) , and further wherein a smooth, hard metering surface (24) and a , - smooth, hard rear surface (28b) available ι are, wherein the support surface (26), the dosing (24) and the rear surface (28b) intersects and forms two smooth, hard edges (25, 28b) over the entire length of the support surface (26), the dosing surface (24) forming an obtuse angle with the support surface (26), so that a hard, durable, polished, obtuse-angled edge is formed on the areal enforcement; that the endless, rotatable, fluid-carrying component (40) is pressed in by the support surface (26), and that both edges (25, 28b) of the elongate, flexible metering part (10, 10 ') are accordingly pressed in along the length of the metering part, (wherein the metering surface (24) of the metering part (10, 10 ') a barrier or a weir for an excess (Liquid supply formed by the textured, elastic .Outseite (45) of the liquid-carrying part (40) is supported and wherein the obtuse angle of the metering part over its length elastically resiliently pressed against the elastic surface (45) of the liquid-carrying member, and wherein the trapezoidal section is further firmly supported in a surface parallel to the support surface (45) against a return from the elastic surface (45). Force applied against the obtuse-angled edge (25) HI. Ill: -. <»\ and which acts against the support surface (26) of the dosing member (10, 10 '); that means for rotating the endless support surface (45) relative to the dosing member (10, 10 ') are provided so that the liquid abuts against the surface of the barrier and the obtuse dosing edge (25) of the dosing member (10, 10'); that a thin, substantially continuous, continuous liquid film (130) is sheared off and metered onto the surface and uniformly from the back surface (28a) and trailing edge (28b) of the dosing member (10, 10 ') of the textured one Surface (45) of the shell of the support member (40) is carried away; that the elastic force which acts on the flexible, elongated support surface (26) of the dosing member (10, 10 ') is sufficiently large to elastically compress the elastic jacket or the elastic surface (45) of the support member (40) along the Edges (25, 28b) of the metering member (10, 10 ') to produce a substantially continuous continuous liquid film (130) which is substantially constant over the length of the metering member (10, 10') and the path of the metered film, as it exits at the trailing edge (28b) of the dosing member (10, 10 '); and that on the liquid mass at the inlet of the metering surface (24) of the dosing member (10, 10 ') and the surface (45) of the elastic outer side (4 5) of the support member (40) adjacent to the obtuse dosing edge (25) of the dosing member (10, 10 ') and the dull edge of the dosing edge are preselected and are sufficiently large to dose the liquid having given flow properties, to one - * - 2416 17 To dose film (130) with the desired thickness, without considerable indentation and thus while avoiding rapid wear or rapid destruction of the dosing member (10, 10 ') or the support surface (45). For this 6 sheets of drawings