DD149186A5 - METHOD AND DEVICE FOR TRANSFERRING FLUID - Google Patents

Abstract

Method and device for transferring fluid to a substrate, in particular for lithographic printing technology. While the object of the invention is to provide a more economical than previously drivable fluid roller with which a gleichmaeszige fluid application is made possible, d. Exer. therein, a method and. to provide a device with gaps which combines both the advantages of a rough roll with the advantages of a smooth, polished roll, minimizing surface friction, and the like. To ensure uniform fluid application. According to the invention, this is achieved by incorporating very precisely into the very hard surface of the column. Columns are interconnected, and the intervening islands have a finely machined surface. The arrangement of the column is disordered, so that it corresponds to a random distribution.

Description

219 249

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Berlin, 10. 9. 198O AP B 41 C / 219 249 57 016 23

Method and device for transferring fluid Field of application of the invention

The invention relates to a method for transferring fluid between cylindrical rollers with a hard and a soft surface in a fluid transfer system, in which the hard cylinder roller is rotated by pressing against the v / eiche roll, and an apparatus for performing the method. Preferred application of the invention in the printing technique, especially in lithography.

Characteristic of the known technical solutions

The transfer of liquid by means of cylindrical valtels has been known for a long time. The formation of the roller often depends on the field of application, the viscosity of the liquid to be applied, the working speed and similar parameters. In the printing industry liquid rollers are used for various purposes, for example, ink is supplied via ink rollers in color systems; in humidification systems fountain solution is fed via rollers; Coatings, pigments and dyes are applied directly to paper or fabric webs or similar webs using rollers. The use of liquid rollers is therefore merely exemplified, and in order to simplify the description it is referred to below only as the printing technique. This does not mean, however

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Limitation of the invention, which of course is also suitable for the transfer of other liquids to other documents with different viscosities.

In large lithographic printing presses usually take place a fluid wetting and an inking. The wetting system requires a controlled supply of wetting fluid through a plurality of in the. Press arranged fold. The supply of fluid must be done at a controlled rate, controlled application rate and controlled uniformity in order to achieve a quality sufficient for printing and to avoid streaks, color gradients, smudges and other adverse influences. Controlled fluid transfer, however, is not only a difficulty for lithographic printing, but also presents difficulties for other applications as well as for different roll forms.

One of the biggest problems in lithographic offset printing is the application of dampening fluid to the surface of the lithographic printing plate, which is difficult to apply uniform amounts in a uniform manner, which is necessary for a reasonably good reproduction quality of the image printed on the paper. A lithographic printing plate is a chemically treated ink sheet in which the printing surface is prepared to receive ink while the areas not intended for printing are hydrophilic or moisture receptive.For printing, a thin layer of wetting fluid is applied to the surface of the printing surface Pressure plate

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_introduced; which is held in the hydrophilic areas but is repelled in the pressure areas. This allows the print areas to absorb color while the non-print areas are separated from the color by the wetting layer.

Numerous rolls for printing technology are already known, for example polished, chromium-coated wetting rolls for lithographic wetting (US Pat. No. 3,259,062). Similar rollers are known from US Pat. Nos. 3,647,525, 3,508,489, 3,168,037 and 3,433,155. The known chromium-coated v / alts have a smooth, polished and chromium-coated surface, which is very hard in terms of their surface properties and which is very soft for the easy application of a fluid layer. Chromium-coated, hydrophilic transfer rollers are therefore widely used in the printing industry, although they have certain disadvantages. For example, a wetting agent, such as alcohol, must be present in the wetting solution. The alcohol reduces the surface tension of the net fluid so that it distributes itself evenly over the polished, homogeneous surface of the roller. However, since alcohol is extremely expensive and becomes more expensive as oil scarcity increases, this is a significant disadvantage.

From US-PS 3,285,169 a roller with a rough surface is also already known. Also known are rolls with a rough surface whose surfaces are soft; the latter, however, have not prevailed. With the familiar hard, rough rolls, which are called söge-

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called "anilox" roll, larger fluid layer thicknesses can be applied than with smooth rolls. However, they also have certain disadvantages, namely their surface is easily damaged due to the production of copper with surface coating. In addition, color often sets in the deep cracks of the "Anilox" -7 / alze.

Further disadvantages of the known rolls are the surface friction, the tendency to form emulsions, the. Fluid turbulence and the resulting unevenness of the transfer. The rough, hard or soft folds were therefore removed from the smooth, polished, hydrophilic, hard surface v-salts, however some of the benefits of the rough rolls were also lost. The same is true of other industrially used dies, and there is therefore a strong need for better liquid transfer rolls,

Wherever fluid transfer occurs through rollers rotating at different surface speeds, which is often the case with controlled operations, the surface shape of the rollers has an immediate influence on the amount of energy applied to the rotation. 3o has a rough roller, which rotates at a speed other than an adjacent roller, a higher frictional resistance. Hard-polished rollers therefore generally require less drive energy when rotating against a rotating and compressing roller at a different speed.

If there is a strong transfer of VIBROUS ³ FLUIDS, for example polymer coatings, then the

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Surface friction even larger, and there is an increased need for improved OB vehicles.

Object of the invention

The aim of the invention is to provide a method and a device for the transmission of fluid that works more economically than before.

Explanation of the essence of the invention

The invention has for its object to provide a method for transferring fluid between cylindrical rollers with a hard and a soft surface in a fluid transfer system in which the hard cylinder roller is rotated by pressing on the soft orphan, as well as to provide a device that has both the advantages a rough 7 / alze combined with the advantages of a smooth, polished roller, d. h., That the risk of surface damage is avoided, the surface friction is reduced to a minimum and a uniform fluid application is ensured.

According to the invention, this object is achieved in that a cylindrical core is coated in a predetermined thickness with a hard material and rotatably mounted as a hard roller, that the coated core to a predetermined depth to remove substantial parts of the coated material and to produce relatively dense, irregularly arranged and relatively deeper, interconnected column in the

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Surface is etched that the surface of the etched core to reduce the density of the interconnected column to 9 to 26 % of the roll surface. polished and an irregular pattern of isolated, smooth-surfaced webs (islands) is formed between the gaps, that the surface of the hard roll for fluid absorption on the polished surfaces of the webs and in the intermediate, interconnected columns is cleaned, that the rotatably mounted on the soft roll by pressing in a hard roll and providing a plush feed to one of the roll surfaces, rotating the hard and soft rolls to transfer fluid over their surfaces and between the rolls; Fluid cross-flow in the interconnected columns of the hard particles is effected to provide dynamic surface action and reduce laminar flow during fluid transfer.

Advantageously, the process of spontaneous generation of fluid cross-talk between the hard and the vee cells includes generating turbulence in the fluid and mechanically reducing the surface friction of the fluid by fluid flow in the interconnected gaps.

In another embodiment, the hard material coated on the core is chromium, and during the etching process, the core is dipped in hydrochloric acid to produce the irregular, relatively deep, interconnected gaps.

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Conveniently, the density of the interconnected gaps is between 14 and 17 % of the 7 / alzen surface.

Preferably, the density of the interconnected gaps is on the order of 15% of the Y / alzen surface area.

According to another feature of the invention, when the cylindrical core is coated to a predetermined thickness, a core is plated with chromium in a thickness of about 0.5 mm, and etching of the core, including electroetching, results in interconnected gaps of a depth of about 0.25 now.

The apparatus for carrying out the method is characterized in that the outer surface of the Fluidv / alze with an irregular, relatively flat gap pattern consisting of interconnected columns and intervening, polished islands is provided, wherein the gaps up to 30 fo the surface of the fluid roll to form a uniform, unhomogeneous fluid sensing surface.

Advantageously, the coated metallic outer surface consists of chromium.

It is particularly expedient if a random gap pattern is etched and polished in the chromium layer.

In a further embodiment, the chromium layer applied to the cylindrical core initially has a thickness of up to 0.5 mm and the average polished slit pattern depth

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is up to 0.075 mm. Preferably, the gaps occupy between 9 and 26 % of the surface of the pluvial roll. According to another feature of the invention, the gaps occupy between 14 and 17% of the surface of the pluvial roller.

It is also according to the invention that the pilot feed means is a soft roll which rotates with the fluid roll.

Advantageously, the Pluidaufbringfläche is a soft roller, which with. the pluid roller rotates. According to the invention, the fluid application surface is a material web movable over the pluid roller for receiving the transferred film.

Preferably, the gaps initially have an average depth of 0.25 mm in the outer surface of the pluvial roll, and after polishing their mean depth in the outer surface is 0.05 mm.

A particular advantage is that, after polishing the fluid roll in the outer surface, the gaps have an average depth between 0.025 and 0.05 mm. Conveniently, the gaps in the outer surface of the plunger roll have a mean width between 0.025 and 0.05 mm.

embodiment

The invention will be explained in more detail by exemplary embodiments v / ground. In the accompanying drawing show:

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Pig, 1; a perspective view of a fluid transfer roller;

FIG. 2 shows an enlarged section through the surface of the transfer roller according to FIG. 1, showing an embodiment of slit patterns; FIG.

Fig. 3! an enlarged view of the surface of the roller of Fig. 1 showing a slit pattern;

Fig. 4, 'another embodiment of the slit pattern of FIG. 3; ,

Fig. 5 © © ine enlarged side view in section through the roller of FIG. 1, showing the fluid transmission.

Fig. 1 shows a fluid roller 10 which is pressed against a second roller 12 and presses it for easier fluid transfer. It can be seen on the fluid roller 10, a gap pattern 14. The nip pattern 14 is formed in a hard cylindrical outer surface 16 of the fluid roll 10 as described below and provides the roll 10 with a distinct, non-contiguous, non-homogeneous surface. When working with the roller 12, the gap pattern 14 gives the fluid roller 10 all the advantages of an uninterrupted, smooth-burnished roller and a rough, knurled or "anilox" roller, without their having both disadvantages. The outer surface 16 is hard and impenetrable to hitting, at the same time depressions

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are present in the form of the slit pattern 14.

2 shows an enlarged, sectional side view of the outer surface 16 and the gap pattern 14 of the fluid roller 10 of FIG. 1. It can be seen that the gap pattern 14 consists of a plurality of interconnected, formed in the outer surface 16 columns 18, the extend in generally predetermined depth and width in the outer surface 16. Between adjacent columns 18 are polished islands 20 which form the surface of the fluid roller 10. The islands 20 are separated by the irregularly extending gaps 18 and allow fluid flow around them. In this way, the outer surface 16 of the fluid roller 10 has a discontinuous, unhomogeneous surface against applied fluids. On the surface either static or dynamically applied fluid first has certain flow properties, which are independent of the type of surface, so smooth or rough. For example, if a drop of water is applied to a known roller, it generally gathers together unless previously treated with a wetting agent to reduce its surface tension. If the g] e drop of water applied to the outer surface 16 of the fluid roller 10 of the invention, then distributed; he felt as if a wetting agent had been added because the interconnected gaps 18 mechanically disrupt its surface tension. This is also done when the drops of water are applied dynamically.

Fig. 3 shows an enlarged plan view of a

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Part of the outer surface 16 of the fluid roller according to the invention 10. There are the random distribution of the column 18 and their substantially uniform width to form approximately equal islands 20 see su. As ^fl random pattern "herein interconnected column understood 18 forming the illustrated and described unzusainraenhängende and inhomogeneous surface. The arrangement of the column 18 is random due to their manufacturing process or irregular. However, they form islands 20 whose size and number are carefully controlled. This constitutes an essential feature of the invention. Another essential feature of the invention lies in the density of the gaps 18 with respect to the smooth islands 20. The gap density or coverage in the embodiment according to FIG. 3 is 14 to 17% dynamic operation for transferring relatively non-viscous fluids such as water has proved an occupancy of about 15 % to be advantageous Furthermore, gap depths of 0.025 to 0.05 mm and about the same width have proven to be advantageous for achieving optimum results.

Fig. 4 shows another gap occupancy of the order of 20 %. It is clear that the numerical value means an average for the column 18 with respect to the islands 20. The size of the column 18 is preferably not affected. However, it has been shown that with increasing gap density in the islands 20 shallow gap recesses arise. If this is done, then this leads to a departure from the switching pattern 14 according to the invention and leads to a recessed '.' / Alzen surface, which is more similar to the prior art and not the inventive

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Has fluid transfer properties. The prior art, provided with recesses roll surfaces cause namely no lateral distribution of the fluid, since the gaps 18 are not interconnected. In dynamic operation. Cleavage pattern 14 according to the invention facilitates the fluid transfer under pressure from a fluid supply device, for example pressed-on rollers. In the following, the term "compression under pressure" is understood to mean the load on rollers in which the profile of one or both is pressed into the other. The gap pattern 14 facilitates in the same way the application of the fluid to the desired surface, since the latter flows in the gap pattern 14.

Fig. 5 shows an enlarged, schematic representation of the fluid roller 10 in operation. Fluid is applied to the fluid roller 10 by means of a second roller 22. The application of fluid can also be done on any other Wei30. In one embodiment, the fluid is transferred under pressure to the fluid roller 10, for which purpose other pressure devices are provided in another embodiment. The second 7 / alze 22 has a Y / oiche outer surface 24 and is pressed at the transition point 26 of the hard fluid roller 10. At the transition of the two rollers 10, 22, a fluid gap 28 with fluid 30 is formed. The fluid 30 is pressed through the transition point 26 and transferred to the fluid roller 10. The thickness of the fluid layer 32 thus formed on the fluid roller 10 according to the invention is more uniform and greater than in the known hard rollers. Although it is also possible to use the known rollers

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however, the quality of the transfer is lower than that of polished hydrophilic 1-yl salts Apart from the fragility of copper-clad rolls, especially when exceeding a certain critical speed, the driving forces give rise At different speeds driven 7 / alzen difficulties, which can deposit residues in columns or depressions.

The manufacture of the fluid roll 10 involves various coating and etching processes, suitable processes being, for example, the production of an inverted form such as the fluid roll 10, namely the manufacture of cylinder liners. The gaps formed are incorporated into the inner wall of the cylinder liner; They are generally very deep to keep oil for smelling purposes. For this purpose, various methods of chromium and iron coating with different slit patterns are known. The Spaltmu sterbildung for cylinder liners causes a Taschonbildung for the storage of oil and the reduction of friction and wear.

These sites, often referred to as "pores", are etched electrically into the hard metal surface. The islands remaining between the pores are honed or polished 20% to give a proper sliding surface. Various electroplating etch processes are known for establishing the desired porosity properties in the smooth surface. So far, however, only cylinder liners have been processed in this way, a reference to the application of this

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On the other hand, processes for the production of fluid rolls can not be found in the prior art. The gap pattern 14 according to the invention for the fluid roller 10 provides a synergistic effect. The flow properties do not match the prior art smooth or rough rolls. Modification of the gap density, gap dimension, and gap ordering described herein provides few advantages without imposing critical drawbacks as well.

The preparation of the gap pattern 14 can be accomplished, for example, in the following way:

First, a cylindrical core is prepared for coating with chromium or a similar coating. The core is aligned very accurately with respect to the coating anode to give a uniform coating. When the deposited metal has reached a predetermined layer thickness on the order of 0.5 mm, it is electroetched, reversing the current and removing portions of the deposited metal. The interconnected gaps 18 extend into the outer surface 16 up to about 0.25 depth, depending on the layer thickness. Subsequently, the etched 7 / alze is honed or polished on a lathe or similar device to reduce the plating thickness, to set the surface dimensions and placement within strict limits, and to obtain the smooth, even islands 20 with gaps 18 therebetween as shown in Figs. 1-4 , The etching and polishing must be coordinated to form the gap pattern 14 according to the invention

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his. As a sufficient, a gap depth between 0.02 ^ and 0.075 mm has proven .. For this, the initial layer thickness of the metal applied to the cylindrical core is often greater than conventional plating, while the etching is carried out in a controlled manner and the polishing with the etching exactly matched is.

For operation, the fluid roller 10 is first treated with a suitable agent, for example for chromium surfaces with hydrochloric acid, to make all surfaces, islands 20 and gaps 18 fluid receptive. Subsequently, the fluid roller 10 is mounted on a fluid supply means and an application area. 1, the fluid roller 10 presses against a soft roller 12, wherein both rollers 10; 12 are either independently or jointly drivable. By the rotating transition points 26 a certain turbulence is transferred to the fluid layer. This turbulence is due in part to a fluid flow in the gaps 18, which substantially interferes with laminar flow in smooth roll surfaces. For example, fluid rings or lobes of laminar fluid flow form on smooth, coherent, hydrophilic surfaces. The dynamic surface effect of the gap pattern 14 according to the invention prevents such ring formation. This is particularly advantageous for lithographic dampening systems where alcohol is often used in the mesh fluid or in the spray solution to reduce surface tension. The use of alcohol and similar wetting agents makes the use of alcohol and similar wetting agents unnecessary, so that more economical fluid transfer is possible.

Claims (18)

219 249 A method of transferring fluid between cylindrical rollers having a hard and a soft surface in a fluid transfer system in which the hard cylinder roller is rotated by pressing against the soft roller, characterized in that a cylindrical core of a predetermined thickness coated with a hard material and is rotatably mounted as a hard roll, that the coated core is etched to a predetermined depth for the removal of substantial parts of the coated material and for generating relatively dense, irregularly arranged and relatively deep, interconnected column in the surface that the surface of the etched core to Reducing the density of the interconnected column polished to 9 to 26 % of '.Valzenoberfläche and an irregular pattern of insulated, a smooth surface having webs (islands) is formed between the columns that the surface of the hard roll to r Fluidaufnähme on the polished surfaces of the webs and in the intermediate, interconnected columns is cleaned, that the hard roller rotatably mounted by pressing the soft roller and a fluid supply to one of the roller surfaces is provided that the hard and the soft V / alze to Transmission of fluid across their surfaces and between the rollers to be rotated, and that a fluid cross-flow in the interconnected columns of hard 7 / alze be effected in order to achieve a dynamic surface effect 219249 2. The method of item 1, characterized in that the process of creating a fluid transverse flow between the hard and the soft roll comprises generating a turbulence in the fluid and the mechanical reduction of the surface tension of the fluid by fluid flow in the interconnected columns. - ¹ o 3. The method according to item 1, characterized in that the hard material coated on the core is chromium and that during the etching process, the core is dipped in hydrochloric acid to produce the irregular, relatively deep, interconnected gaps. 4. The method according to item 1, characterized in that the density of the interconnected column zv / ischen 14 and 17 7 <> - the roller surface. 5. The method according to item 4, characterized in that the density of the interconnected column is in the order of 15 7 ° of the roll surface. 6. The method of item 1, characterized in that when coating the cylindrical core to a predetermined thickness, a core is coated with chromium in a thickness of about 0.5 um and that the etching of the core including an electro-etching interconnected column with a depth of gives about 0.25 mm. 7 · Apparatus for carrying out the method according to 219 249 _ ₁₈ _ 8. Device according to point 7 »gekannzeichnet in that the coated metallic outer surface (16) consists of chromium. 9. Device according to the points 7 and 8, characterized in that in the chromium layer, a random gap pattern (14). etched and polished. September 10, 1980 AP B 41 C / 219 10. Device according to items 7 to 9, characterized in that the chromium layer applied to the cylindrical core initially has a thickness of up to 0.5 mm and in that the mean polished slit pattern depth is up to 0.075 mm. September 10, 1980 AP B 41 C / 219 249 the points 1 to 6, characterized in that the outer surface (16) of the fluid roller (10) with an irregular, relatively flat gap pattern (14) consisting of interconnected columns (18) and interposed, polished islands (2Ö) is provided take the gap (18) up to 30 7 ° of the surface of the fluid roller (10). 10. 9. 1980 ¹ AP 'B 41 C / 219 249 and to reduce laminar flow during fluid transfer. September 10, 1980 AP B 41 C / 219 249 Invention claim h 11. The device according to points 7 to 10, characterized in that the gaps (18) occupy between 9 and 26 % of the surface of the fluid roller. 12. Device according to items 7 to 11, characterized in that the-column (1Ö) occupy between 14 and 17 % of the surface of the fluid roller. 13. Device according to the points 7 to 12, characterized in that the fluid supply means is a soft roller (22) which rotates with the fluid roller (10). , 219 24 9 _ ₁₉ _ 14. Device according to items 7 to 13 »characterized in that the fluid application surface is a soft roller (12; 22) which rotates with the fluid valve (10). Device according to points 7 to 14, characterized in that the fluid application layer is a material web movable over the fluid roller (10) for receiving the transferred fluid. Device according to points 7 to 15, characterized in that the gaps 18 initially have an average depth of 0.25 mm in the outer surface (16) of the fluid roller (10) and that after polishing their mean depth in the outer surface (16) is 0.05 mm. The device according to items 7 to 16, characterized in that the gaps (18) after polishing the fluid roller (10) in the outer surface (16) have an average depth between 0.025 and 0.05 mm. 18. Device according to the points 7 to 17 »characterized in that the gaps (18) in the outer surface (16) of the fluid roller (10) have a lying between 0.025 and 0.05 mm average width. For this ..2d - .. soap ^ drawings