DE1411118C - Moistening device for the printing plate of an offset printing machine - Google Patents

Description

The invention relates to a moistening device for the printing plate of an offset printing machine with an application roller resting on the plate cylinder, which feeds the dampening solution independently over two Driven by the application roller rollers is supplied, one of which is on the application roller Adjacent transfer roller with a continuous, uninterrupted, hydrophilic surface and the other is a roller with a non-absorbent, smooth surface.

Humidifiers of this known type have proven very useful. You have predominantly the previously customary fabric covers that work with intermediate rollers with dampening solution absorbent Damp units displaced. In these devices, the dampening system drive is independent of the Machine by a control motor, through which the speed of the dampening roller is independent of the speed the printing plate can be changed and the dampening can be finely regulated. The speed the dampening roller is not adjusted according to the running speed of the offset press, but according to the Water requirement of the plate and its print image set. The slower the dampening rollers run, the more less fountain solution is applied. The water supply is continuous, and with the elimination the reciprocating moisture siphon of earlier dampening systems eliminates possible causes for uneven Dampening.

In another known dampening device, those from an inking roller are by friction entrained dampening rollers adjustable relative to one another for the purpose of controlling the dampening. There is a setting between the inking roller and the dampening solution roller resting against it not possible, so that an exact setting of the dampening solution to be transferred to the inking roller is not guaranteed.

It is also known to arrange all dampening rollers and the inking roller one behind the other so that the set pressure of the first dampening unit roller over all subsequent rollers up to the inking roller transmits so that the same pressure prevails between all the rollers resting against one another. With different Roll diameters and / or different roll lengths arise between the rolls a different surface pressure, so that an exact gap dimensioning between the in mutual System stationary rollers for the purpose of favorable dampening solution measurement is not possible.

In the practical operation of dampening devices of the type mentioned at the beginning, it has been shown that that it can be done solely by regulating the speed of the transfer roller independently of the offset press and also ■ by joint adjustment of all dampening rollers connected in series, the one for one Emulsification-free moistening of the printing plate required, axially evenly distributed thin dampening solution layer onto the transfer roller and from this evenly onto the application roller in the desired Transfer amount and at the same time prevent printing ink from the printing plate or from the inking unit to the transfer roller. It is therefore the object of the invention to provide a humidifying device specify with which one can be adapted to the respective printing conditions Fountain solution layer applied to the printing plate evenly distributed in every respect can be. Starting from a humidifying device of the type mentioned above, blow Invention to solve this problem before, dal two dampening rollers to one structural unit are summarized, the setting of the Sf between the applicator roller and with it to maneuvering dampening solution transfer roller by means of a first adjustment device adjustable and that further the gap between the two Fei

ίο central rollers by means of a second adjustment device is adjustable regardless of the position of the unit to the support roller.

The inventor has recognized that a besor precise setting of the transmitted moisture quantity is only possible if in addition to a drive that is independent of the application roller Dampening rollers the pressures and the rollers] between the dampening rollers below on the one hand and between the last dampening unit and the inking roller on the other hand independent can be adjusted from each other. The intended summary of the the dampening roller to a unit b thereby the prerequisite that at Verstel the pressure or the roller gap between the dampening unit rollers does not impair the position of the last dampening unit roller in relation to the application roller (and vice versa) takes place. The independent and uninfluenced unity of the dampening and transmission wa proves to be of particular advantage for a moderate further development of the invention, according to it is provided that the transfer roller sic] in a known manner at both ends Application roller extends addition. In the case of the type of transfer roller used in E: dung 1 the dampening solution is centered at the ends of the metallic circumferential surface of the transfer wi With the same length of transfer and applicator roller, more dampening solution would be on the En the applicator roller than to be transferred to the middle, so that no uniform dampening of the printing plate can be achieved as a result of the length provided according to the invention graduation of the transfer and application roller and the contact surface between them is different Roll out the one between the moist milks. These differences can be seen through independent adjustability of the roller gap according to the invention, the respective printing conditions balance accordingly.

According to one embodiment of the invention, it is seen that the application roller is an inking roller which, when the structural unit moves from the A

Carrying roller away while executing a circular arc

shaped movement around the axis of them with Dru

ink supply roller of the inking unit with

Spring force is lifted from the plate cylinder

To further improve the evenly!

the dampening solution application, the invention is further developed in that the uninterrupted hydropl Peripheral surface of the transfer roller from a gl; polished chrome layer, on the surface a protective shield to prevent oxidation

by treatment with a solution of a chromium oxide corrosive agent, gum arabic and water is formed.

The invention is illustrated below with reference to

3 4

Embodiments shown in the drawing will have a chrome surface during their usual

explained in more detail. In the drawings, manufacture is exposed to air, so it forms on

F i g. I a schematic representation of a slightly chromium oxide from this area. This chromium oxide

management of the dampening system according to the invention prevents water absorption by the surface,

in printing position, 5 The chromium oxide forms a water-repellent, hydro-

F i g. II one of the F i g. I similar view of the phobic or chemically greasy surface, which

The dampening unit is in a non-printing position, whereby printing ink accepts. The one described below

Both the transfer roller from the application treatment is used to remove the chromium oxide from the

roller and the application roller from the printing surface of the transfer roller 14 to remove

plate is lifted, io and after this treatment a new formation of

F i g. III to prevent an enlarged schematic view of the chromium oxide on this surface.
Relative position of the lifting roller, the transfer In order to achieve this, the chrome surface with roller and the application roller as well as the layers consisting of a solution of a part of hydrogen chloride or rollers, of dampening liquid and sulfuric acid, a part of a solution of rubber printing ink , with the 15 arabic in water, 14 ° Be, and part of the water printing press is in the printing position. The acid dissolves and removes the chromium

F i g. IV a schematic view of another oxide and the gum arabic solution coats the

Embodiment of a in its pressure position surface of the chrome and prevents a new one

located dampening system, in which a single roller, oxidation. The time during which the chrome surface

which is not an inking unit roller, which must be exposed to this mixture as an application roller, depends on

is applied, which is between the chrome plating and the surface

F i g. V one of the F i g. IV similar view, in the processing of the past time and of the treatment

the transfer roller out of contact with the an ment. The longer the surface is exposed to air

the roller adjacent to the pressure plate is standing and the one has become, the thicker the chromium oxide layer,

zelwalze is lifted from the printing plate, and 25 The treatment of the roller is preferably carried out

F i g. VT is an enlarged partial view showing that with acids. But it is also possible to use the chromium oxide Setting the distance between the front ends of the transmission by simply grinding and polishing the roller and to remove the applicator roller and the water ring surface, thereby removing the surface shows at the front end of the transfer roller. When the roller is in front of it, it absorbs water

Does not come into contact with air when used in Figs. I and II as well as IV and V 30,

The offset press shown here is only the plate cylinder. Oil can also be deposited on the surface of the roller.

the A with the pressure plate 20 and which are brought with this to prevent oxidation of the roller

Cylinder cooperating rollers to prevent the staining from their polishing, provided the roller is not

and the dampening system. is used immediately.

The printing ink is attached to the cylinder A.

th printing plate 20 over a number of order-mentioned type, it is desirable that when transferring

rollers fed from the metallic colors of the printing press in the non-printing position and

Distribution rollers 1 and 2 with rigid surfaces when idling during the filling of the paper

and the order whale supply made of hard rubber or for other reasons the transmission

zen 3, 4, 5 and 6 exist. These rollers rotate 40 roller 14 is lifted from the application roller 6,

by touch. to avoid an accumulation of moisture on the

In the press shown in Fig.I and II support roller6 and the return of moisture

the dampening unit consists of a lifting roller 7 and the inking rollers that are attached to the application roller

a transfer roller 14, and the dampening liquid to prevent. At the same time, however, it is also

speed is directly requested by the one in the container 8 that the transfer roller 14 is constantly

dipping Hebevwalze 7 is supplied to the transfer roller moisture, so that the printing press

14 and from this to the inking unit roller 6 in which it is immediately ready for printing when an adjustment is made

later described in detail. on printing.

The transfer roller 14 preferably consists of the dampening unit including the container Metal and has a highly polished outer surface, 5 ° ters 8 for the dampening liquid and the rollers 7 and which has been treated in such a way that it absorbs moisture into a unit which can be applied to a takes. Preferably, the surface of the over-sliding frame 50 is arranged in a through Carrying roller 14 is plated with chrome, is polished and parts to be described are precisely adjustable treated after plating with chrome so that bare contact position on the applicator roller 6 or from it absorbs water. The surface of the over- 55 this can be moved away. One frame part each Carrying roller is perfectly smooth so that none of the sliding frames are at either end Irregularities or rough surfaces present on the printing press.

on which printing ink could settle. The sliding frames 50 are supported by transverse slots 51

when the moisture settled on the surface permeates, in which attached to the press frame

Keitsschicht in the rotation taking place under pressure 60 pins 52 are sliding, which serve as a guide for the

the application roller from these irregularities serve sliding frames.

or rough surfaces perforated or torn. A spring 53 is between one of each slide would. Approach 54 carried on this irregular or rough frame 50 and one on the press surfaces existing tips, which are arranged on pins 55 attached to the wet liquid frame. the The compression 65 springs 53 are stretched when the sliding frame 50 colored surface of the applicator roller, and would take their inner position (Fig. I). The feathers Given these circumstances, the ink 53 pulls the frames 50 outwardly from the face transferred back to the dampening unit. Carrying roller 6 away when a shaft 59 is attached

continuous crank arm 60 and a roller 61 carried thereby in the right direction in that described below Way to be rotated. A crank arm 60 can be provided at each end of the printing press being.

A stop 56, which limits the outward movement of the frames 50, rests against the shoulder 57 of the frame 50. when a hand lever 58 attached to the shaft 59 is rotated, around the roller 61 after

or a pulley 71 and around a sprocket or a pulley (not shown) which is attached to the shaft 7 α of the lifting roller 7.

It is desirable that the speed of the roller 7 is variable to the recorded and on the Transfer roller 14 to regulate the amount of dampening liquid transferred and also to regulate the surface speed the transfer roller 14 to change. For this purpose there is a control panel 74

to move above so that the frame 50 with respect to io a variable resistor 75 arranged, the

can move on the applicator roller 6 to the outside.

By moving the hand lever sideways, the crank arms 60 and those carried by the arms Rollers 61 are moved on a sheet, as shown in dashed lines in Fig. · I is.

An upper stop 62 carried by the press frame rests against the roller 61 and limits the arcuate downward movement of crank arm 60.

Power supply is regulated by an off-on switch 73. A pointer 75 α and on the resistor 75 attached graduations show the desired engine speed.

The variable resistor 75 is connected in series with the motor 72 and therefore can be used to change the speed of the motor 72. The transfer roller is via a gear train driven by the roller 7, so that the rotation

A lower stop 63 limits the movement of the 20 of the roller 14 also from the resistor 75 crank arm 60 and determines the position that will apply. The independent drive can also through Transfer roller take place relative to the application roller a different device, takes. Preferably, in the case of the FIG. I and II represent

Between the shaft 2a of roller 2 and the embodiment provided, and also in the later shaft 6a of the application roller 6 is an arm 64 forward 25-described embodiment according to Fig. IV and V hands, which is mounted on the shaft 2 a rotatable, So the roller 7 has an elastic smooth surface, so that when the transfer roller 14 is shifted to the right by the shifting of the sliding frames, the liquid transferred to the transfer roller 14 is evenly distributed Spring 65 The F i g. IV and V show a slightly different one

(Fig. I) relaxes and the applicator roller 6 of 30 embodiment, which stands out from the first embodiment of the printing plate 20, when the printing press differs in shape in that a single non-printing position is set. The roller 91, which is not an application roller of the printing press spring 65, is rotatably seated on a shaft 92 between a spring 65 carried by the arm 64, which is arranged between the pin 67 and a spacing attached to the press frame, getra pin 66 from the press frame. Stops 68 and 69 place 35 dedicated pivot arms 86 is attached. The rotating arms 86 are attached to the shaft 6 α and limit the side movements are rotatably mounted on a shaft 87. The upper movement of the applicator roller 6 in both directions. Ends of the pivot arms 86 carry pins 90 on which

When the hand lever 58 moves to the left, springs 88 attack, the other ends of which are attached to the (Fig. II) describes the crank arm 60 a left press frame attached pin 89 are anchored, directed arch, so that the sliding frame 50 after 40 stops 93 and 69 limit the lateral movement left and are moved to the printing plate 20, since the gene to support the roller 91 are used Slides 51 slide onto pin 52. This moving wave 92.

The transfer is continued until the transfer occurs when the

roller 14 rests against the application roller 6 and the slide-on frame 50, seen in FIG. IV, the support roller 6 presses against the pressure plate 20. The 45 transfer roller 14 to the single roller 91 and contact with the pressure plate 20 is limited by the adjustable stop 68 pushes the roller 91 when the arms 86 rotate. The parts then abut shaft 87 to plate cylinder A as shown in FIG. I position shown. the pressure plate 20. The springs 88 are tensioned,

During this movement, the springs 53 and 65 are so that when the sliding frame 50 curious; excited. When the hand lever 58 and 50 is moved to the right, these springs are relaxed and meanwhile Crank arm 60, arms 86 and that of arms 86 in the opposite order device, the springs 53 are relaxed and move carried roller 91 lift off the pressure plate 20, the sliding frame 50 to the right, and the springs 65 in both versions according to FIG. I and II or

are relaxed and move the application roller 6 IV and V is a pressure adjustment screw 94 vorhannach right until the shaft 6 α of the application 55, which applies the pressure between the lifting roller 7 and roller 6 to the stop 69. If necessary, the transfer roller 14, which will be described later, can simultaneously control the printing press for non-printing purposes.

Position can be adjusted. In Fig. II there is a better illustration of the operation of the

the printing press in the non-printing position. written dampening is in Fig. III in one

Like F i g. II shows, the lifting roller 7 lies on the 60 enlarged, exaggerated in dimensions Transfer roller 14 rotating, so that a large cut the lifting roller 7, the transfer roller 14 and the application roller 6 and the roller 2 are shown.

The lifting roller 7 is immersed in the dampening liquid 9 present in the container 8 and contacts the transfer roller 14. The pressure between these two
Rolling is regulated by the adjusting screw 94 so that
that the surface of the transfer roller 14 in the

The dampening liquid layer is maintained on the surface of the transfer roller 14 when the press is in the non-printing position.

The lifting roller 7 is driven by the electric motor 72 via a chain or belt 70, around a sprocket driven by motor 72

Surface of the roller 7 is pressed in, as the indentation 81 shows. After setting is for usually no readjustment is required while the printing press is in operation.

When the roller 7 is rotated in the direction of the nip located between the rollers 7 and 14, a relatively thick layer of dampening liquid is created 79 captured by the surface of the lifting roller 7 and carried along. At the tangent point or at the point of reversal between the Rollers 7 and 14 collect a damming bead 80 made of dampening liquid, the thickness of which is thereby regulated is that the excess water trickles back into the container 8 by its own weight. The bulge 80 forms a reservoir from which the dampening liquid is drawn off by the transfer roller 14 will. When the rollers 7 and 14 are in contact with one another, one becomes relative thin layer of dampening liquid between the touching surfaces of the two rollers measured. Since the transfer roller 14 has been treated so that it has a smooth water-absorbing

, mende surface, part of this dampening solution layer adheres as layer 82 on the surface of the roller 14, while the remaining part as layer 83 trickles back to the liquid 9 in the container 9. The dampening liquid layer 82 is on the surface of the roller 14 by the rotating and squeezing action between the rollers 7 and 14 equally distributed.

The dampening liquid layer 82 remains on the surface of the roller 14 and comes with that on the The layer 78 of viscous printing ink located in the applicator roller 6 at the feed nip 95 of the rollers 6 and 14 in touch.

At the intake gap 95, the transfer roller 14 is pressed into the elastic surface of the applicator roller 6. The dampening liquid layer 82 has an outer surface 96 resting against the ink layer 78 and an inner surface 97 adhering to the surface of the roller 14, so that the layer 82 in

j Reality is the surface of roller 14 from the layer of printing ink 78 present on roller 6 separates. It is true that there is a hydraulic connection between the rotating ones close together Rollers 6 and 14 are present, but there is no physical contact between the rollers 6 and 14.

: The dampening liquid layer 82 enables the

; Rollers 6 and 14 move at different surface speeds to turn. Preferably, the applicator roller 6, which is usually rotated at the same surface speed

: like the printing plate 20, rotated at a higher surface speed than the roller 14. The roller 14 can, however, also be rotated faster - than - the - roller 6, the same tasks being carried out and the same results being obtained. If the surface speed of the roller 14 is increased, the dampening liquid layer 82 is fed to the nip 95 more quickly, and "a larger amount of dampening liquid is transferred to the surface of the ink layer 78 and to the printing plate 20. The opposite is the case when the surface speed of roller 14 is reduced.

The dampening liquid layer 82 between the contact surfaces of the rollers 6 and 14 enables the rollers 6 and 14 to rotate smoothly at different surface speeds because the layer 82 actually forms a lubricant which allows the rollers 6 and 14 to slip without abrasion. As a result of this slippage between the rollers 6 and 4 , the dampening liquid layer 82 is calendered, smoothed, measured and distributed between the 'contact surfaces of the rollers 6 and 14, so that the thickness and

ίο amount of layer 82 is safely regulated by this device. .. ■ '■■■ -.

The speed of rotation of the 'roller 14 is from the rotational speed of the lifting roller 7 via the speed control gear 75 or on regulated in another way, so that by increasing or decreasing the speed of rotation of the roller 14 the extent of existing between the contact surfaces of the rollers 6 and 14; Water layer through Change of the relative surface speed and the amount of slip between the rollers regulated can be. By regulating the pressure present between the rollers 7 and 14 by means of the Pressure regulating screw 94 can also adjust the thickness of the dampening liquid layer 82 to a certain extent be managed.

As a result of the positive drive between the motor 72 and the lifting roller 7, any excessive drive from the application roller 6 to the roller 14 is prevented. If the rotation of the plate cylinder A, which is in contact with the application roller 6, is accelerated, then the relative speed or rotation transmitted to the roller 6 is not transmitted to the roller 14 as a result of the positive drive between the rollers 7 and 14. The transfer roller 14 can therefore be rotated at a predetermined speed in order to apply the desired amount of dampening liquid for the respective printing job to the printing plate 20, but the speed can be adjusted and controlled as required. The roller 14 can also be positively driven by a drive device which acts directly on the roller 14 and regulates its speed or rotational speed in any way. .

When the rollers 6 and 14 rotate away from the gap 95, the dampening liquid layer divides 82 at point 98 into a layer 84 which is on the surface of the viscous on roller 6 Ink layer 78 adheres, and into a layer 85 that adheres to the surface of the transfer roller 14 adheres, from which the layer 85 back to the 'dampening solution damming bead 80 is directed.

It has already been mentioned that the moist liquid layer 82 in the gap between the rollers 6 and 14 is smoothed, distributed, measured and regulated. The interfacial tension between the outer surface 96 the dampening liquid layer 82 of low viscosity and the ink layer 78 of high viscosity due to the molecular attraction that the smoothed and regulated layer 84 on the surface the ink layer 78 adheres to the gap 99 between the printing plate 20 and the applicator roller 6 is transferred directly to the printing plate. The low viscosity dampening liquid adheres adheres to the high viscosity ink layer 78 and moves with that layer. The ink layer 78 high viscosity does not stand out and does not adhere to the dampening liquid layer

■. 009519/7

low viscosity. As a result, no printing ink is fed back into the dampening unit.

Beyond this gap 99, no noticeable amount of dampening liquid remains on the roller 6. The small amount of dampening liquid which passes through the gap 99 is passed on to the printing ink layer 78 and transferred to the printing ink layer 77 on the ink distribution roller 2, on which the dampening liquid layer is distributed and then absorbed so that there are no disadvantages in the inking unit.

As a result of the regulated and evenly distributed layer 82 on the transfer roller 14 and as a result the very thin regulated layer 97 created by the slippage between the tangent points of the rollers 6 and 14 is formed, there is no return of printing ink from the printing ink layer

78 on the surface of the roller 14, since this layer of printing ink is actually from the roller 14 is separated by a moist liquid layer.

However, a very small amount of ink should have been transferred to the transfer roller 14 be or should be printed patterns by the ink layer rotating in contact with the printing plate 20 78 have been transferred, then these quantities and patterns are rubbed off by the slip occurring between the rollers 6 and 14 and deleted and are absorbed and distributed by the dampening solution damming bead 80 and the water waste

79 supplied so that the printing ink is not transferred to the surface of the roller 14 or is at the gap of the rollers 6 and 14 accumulates.

As already mentioned and as is known in printing technology, the regulation is based on the pressure plate transferred amount of dampening liquid is of particular importance in offset printing. Other known Dampening units often transfer too much moisture to the printing plate, so that the mentioned undesirable effects arise. By using the dampening system described, the The amount of dampening solution is very precise and very fine to that required for the respective printing process The amount can be adjusted so that no dampening liquid droplets collect on the printing plate, there is no excessive application of dampening liquid to the paper supply and furthermore the Disadvantages are avoided when applying too large amounts of dampening liquid to the printable Areas arise. In general, with the new dampening system, high-quality and produces unsurpassed print quality.

Although it is common to use the inking roller 6 as a transfer roller between the roller 14 and the To use printing plate 20, but this transfer roller does not need an inking roller as found in many offset printing presses. It can also be a single roller, e.g. B. the Roller 91, the surface of which has been treated to receive a greasy layer such as printing ink. The surface can also be otherwise treated to provide a receiving surface for the Forming dampening liquid layer 84 when the transfer roller 14 rolls on the roller 91.

With the new dampening system, there is a closed layer of dampening liquid the surface of the ink layer located on the applicator roller 6, as a result of the Friction and slip between the rollers 14 and 6 or the rollers 14 and 91, so that between the surfaces of the rollers 6 and 14 are constantly distributed laterally and evenly distributed, uninterrupted, closed wet liquid layer is present, the one Prevents printing ink from being fed back into the dampening system.

F i g. VI shows the arrangement and design of rollers 6 and 14 or rollers 91 and 14. It it was found that the wet liquid is in a relatively thick strip 102 (exaggerated large) can accumulate at the ends of the transfer roller 14. So none If these excessively large accumulations are transferred to the application roller 6, the transfer roller has 14 on the ends of the applicator roller 6 or 91 extending widening 101.

A dampening system with a complete interfacial system is created in the dampening liquid is transferred to the applicator roller and then to the printing plate without a there is a physical connection between the dampening liquid supply and the printing plate in which however, the rollers for transferring the dampening liquid to the surface of the printing plate are hydraulic are separated by the dampening liquid layer, which is caused by the slip between the corresponding Rolls is properly spread out and spread sideways; which is also not just a flawless one Distribution and a uniform layer of dampening liquid is generated, but also an accurate one Volume control allows, so that there is a security that the non-printing areas of the printing plate are moistened with the correct amount of dampening solution and no excess dampening solution is available.

Claims (4)

Patent claims: 1. Moistening device for the printing plate of an offset printing machine with one on the plate cylinder adjacent application roller, which the dampening solution over two independent of the Application roller driven rollers is supplied, one of which is on the application roller Adjacent transfer roller with a continuous, uninterrupted, hydrophilic surface and the other is a roller with a non-absorbent, smooth surface, thereby characterized in that the two dampening rollers (7, 14) form a structural unit (50) are summarized, the adjustment of the gap (95) between the application roller (6, 91) and the dampening solution transfer roller (14) cooperating with it by means of a first Adjusting device (56, 58, 60, 63) is adjustable, and that further the gap (81) between the two dampening rollers (7, 14) by means of a second adjusting device (94) independently of the position of the structural unit (50) in relation to the application roller (6) is adjustable. 2. moistening device according to claim 1, characterized in that the transfer roller (14) in a known manner at both ends over the application roller (6, 91) extends beyond. 3. moistening device according to claim 1 or 2, characterized in that the applicator roller (6) is an inking roller that moves the assembly (50) from the applicator roller (6) away while performing an arcuate motion around the axis of them with Ink supply roller (2) of the inking unit by means of spring force from the plate cylinder is lifted. 4. Humidifying device according to one of claims 1 to 3, characterized in that the uninterrupted hydrophilic peripheral surface of the transfer roller (14) from a smooth polished chrome layer, on the surface of which there is a protective layer preventing oxidation by treatment with a solution of a chromium oxide attacking agent, gum arabic and water is formed. 1 sheet of drawings