FI81998B - ANORDNING FOER EXAKT DOSERING AV VAETSKEFILM PAO EN ROTERANDE VALS I EN TRYCKMASKIN. - Google Patents

Abstract

In order to provide minute dosing of a liquid-film on a rotating roller (5) of a printing press so as to achieve the necessary thickness for subsequent processing, a wiping band (14) is so positioned that it wraps round the roller (5) to an adjustable angle ( alpha ). By this means, the liquid-film (13) produced by a liquid-dispensing unit (7) is partially removed. The rotating roller (5) transfers the minutely dosed liquid-film (24) directly onto the form cylinder (4) of a printing press.

Description

L 81998

Device for accurately dispensing a liquid film onto a rotating roll of a printing press. - Anordning för exakt dosering av vätskefilm pä en roterande Vals i en tryckmaskin.

The invention relates to a device for dispensing and leveling on a rotating roll of a printing machine a liquid film formed by a liquid applicator consisting of an ink or a wetting agent with a liquid-permeable strip wrapped around the rotating roll and wiping off excess paint which falls into the with each turn of the rotating roller.

DE-OS 2146045 discloses an apparatus in which an office offset roll dyeing device for dispensing dye tensions a gauze against a dye cylinder. The circumferential speed of the color cylinder is considerably lower than that of the cylinder containing the printing plate. For this reason, it is necessary to place a second roll behind the intermediate cylinder which rotates with it at the same circumferential speed and receives the color from it and transfers it to the 1st color roll which rotates at the same circumferential speed as the printing plate cylinder. The pendulum movement of this second roll, by which it takes color from the color cylinder and transfers it to the 1st color roll, does not produce a uniform color film on the 1st color roll required for dyeing the printing plate. Therefore, a number of other ink rollers must be placed between the 1st ink roll and the printing plate cylinder to even out the unevenly conducted color before the printing plate so that a uniform ink film can be transferred to it.

In addition, devices are known which can be used to dispense liquid onto a roll so that a usable liquid film is formed without friction rollers. DE-OS 28 12 998 discloses a roll which directly dyes a printing plate cylinder. It is equipped with a soft, flexible rubber surface. The paint applied to the roll from the color box is wiped off with a color knife so that the color film remains as thick as required for further processing. However, this means - because the thickness of the color film varies by a few thousandths of a millimeter - - that the color knife is pressed to overcome the hydrodynamic pressure. very strongly against the roll, whereby the surface of the roll is flexibly deformed -2- 81998. This inevitably causes heating and wear, depending strongly on the speed.

In DE-OS 32 17 569, in front of the rubber dyeing roller according to DE-OS 28 12 998, there is a rigid surface color cylinder on which the dosing elements produce an ink film to avoid deformation of the soft roller surface.

This added color distribution roller, which makes the system more expensive, must be exactly the same size as the platen cylinder to avoid false images. However, a second color application roller must be placed between the platen cylinder and the color cylinder to prevent the two hard-surfaced rollers from colliding.

The color film produced by the color application roller is not smoothed and completely renewed. The film left by the printing plate cylinder on the color application roller is covered with a new color in the next round. This is repeated with each round, which can lead to soiling and a messy print. Contamination can also lead to contamination of the dispensing gap, resulting in uneven color supply and increased wear. At the same time, there is a risk of agglomeration due to the film remaining on the color cylinder, which must be eliminated in some way.

The requirements for the accuracy of the dosing element and the color cylinder are very high, which is reflected in the price of this dyeing device.

The object of the invention is to provide a device which makes it possible to produce a precisely metered liquid film on a rotating roll with the smallest possible number of rolls, a new film being created and leveled with each turn of the rotating roll. In addition, the device avoids the other mentioned disadvantages.

According to the invention, the solution is obtained in such a way that the rotating roll is adjacent to a cylinder containing a parallel printing plate and moves at least one sweeping belt rotating the rotating roll.

II

-3- 81998 for a thick film of liquid film dispensed to a suitable thickness. The circumferential speed of the rotating roll is practically the same as that of the printing plate cylinder.

The structure and hardness of the surface of the rotating roll of such a device can be almost arbitrarily adapted to the printing method, the fluid used and the operating speed. The dosing screws and their expensive guide device for dosing the liquid film on the rotating roll fall off. The belt can be modified and adapted to the course of the work, because due to the hydrodynamic pressure, only liquid friction is created between the sweeping belt and the rotating roller, whereby wear is minimal.

Application examples of the device according to the invention are shown in the drawings, which are illustrated in more detail below.

Fig. 1 shows a simplified side view of an apparatus of a printing machine having a device in the form of a scanning tape wound on rolls for producing a precisely dispensed liquid film, Fig. 2 shows a side view of a roll and an endless belt; 3 shows another embodiment of the sweeping tape.

Fig. 1 schematically shows the apparatus of a printing machine, in which a printable paper web 1 is inserted in a known manner between a rubber cylinder 2 and a back pressure cylinder 3, which are mounted for rotation in a machine frame (not shown). Associated with the rubber cylinder 2 is a printing plate cylinder if, which transfers the printed image to the rubber cylinder. The printing plate cylinder if receives color and / or wetting agent from the rotating roll 5. It, like the rubber cylinder 2 and the printing plate cylinder if, is used with a known device (not shown) and has the same circumferential speeds of -4-81998.

The rotating roller 5 receives liquid from the applicator 7, which is delimited by e.g. the rear wall 8, the side walls 9, the metering knife 10 and the rotating roll 5. The distance 11 between roller 5 takes with you. For example, an iron or metal woven scanning tape 11 * is wound on the shafts at both ends.

The other end is braked by a shaft 15 which is fixed but rotatably mounted, and a second end used in kelausakselil Ia-16, which kietoutumiskulraan λ may be set as shown by arrow 18 keeps in any case a curved guide 17.

The tension of the sweeping strip 11 * can be changed by the braked shaft 15. The shaft 15 and the shaft 16 to be used allow, for example, the simplest change of the position of the worn-out strip 11 * in the direction of the arrows 19 and 20 by winding, which can of course take place during use.

The sweeping belt 11 * wipes away the liquid adhering to the rotating roll 5, whereby the wiped liquid 21 is directed to the collecting tank.

22. From there, the liquid 23 enters a known device along non-shown lines. The rest of the liquid film 21 * is then fed to the printing plate cylinder 1 *. Thereafter, the still liquid 25 is completely renewed in the liquid tank 7.

Depending on the printing method, the rubber cylinder 2 can be replaced by a back pressure cylinder and the printing plate cylinder 1 * by a printing plate cylinder corresponding to the printing method. The web to be printed then passes between these cylinders.

Figure 2 shows an embodiment of a liquid film dispensing device for a rotating roll 5, in which the sweeping belt 11 * is implemented as an endless belt 21 * passing through rollers. to be used

II

-5-81998 The roller 25 is fixed by a rotating, fixed shaft 26 which is driven by a steplessly adjustable motor 27. The rotating roller 28 is by a shaft 29 which can be moved to set the winding angle. The tensionable roller 50 is mounted for free rotation on a shaft 31 located at the end of the lever 32. Lever 32 can be rotated about a fixed shaft 33. Its other end is hinged to a pressure cylinder 34 rotatably articulated to a fixed bolt 35. This pressure cylinder 3b achieves the pressurizing pressure of the medium by applying the required tension to the endless strip 24. The rotating roll 5 has a hollow space 36 which allows any cooling it may need.

By using the endless belt 24, it is possible to keep the relative speeds of the rotating roller 5 and the endless belt 24 driven by the motor 27 always the same, regardless of the speed of the machine. This produces a flawless and regular fluid film on the rotating roll 5 at all production speeds.

The device shown in Figure 3 is also provided with an endless strip 24, such as the implementation of Figure 2. The strip 24 passes through a driven roller 37, a pivoting roller 38 and a tensionable roller 39. The roller 37 is driven by a steplessly adjustable motor 27. Another roller 41 on the fixed shaft 42 is in a cleaning basin 43 with a cleaning agent 44. The basin 43 can be lowered to a lower position 45 when not in use. The strip 24 passes from the basin through a device 46 or 47 which removes excess cleaning agent therefrom, e.g. by sweeping. Depending on the direction of the belt 24, either device 46 or 47 is in operation. This arrangement also makes it possible to clean the rotating roll 5.

Figure 4 shows an implementation of the sweeping tape. It consists of a membrane 48, which is e.g. metal or plastic. The side of its rotating roll 5 is flat and is provided with rows of holes 49. For example, oval holes 50 allow the liquid swept across the bridges 51 between them to drain and drain into the collecting basin 22.

-6- 81998

Figure 5 shows another embodiment of the sweeping tape used for the described device. The inextensible but flexible strips of tape 52, 53 and have bridges 55 with a mutual distance of a. The space% formed between them allows the liquid swept across the bridges 55 to run off and drain into the collecting basin 22. (Figure 1).

With the strip implementations shown, the best possible adaptation to the working conditions required by the printing method can be achieved by choosing the material of the tissue-like scanning strip, the fineness of the fabric, the shape and size of the holes 50 or the width and distance of the bridges. With the possibility of setting the tension of the strip and the winding angle *, practically any thickness of the liquid film can be provided for the rotating roll 5.

All modifications of the present invention can, of course, be automated, in which case, for example, the setpoints are stored in the memory of the control device, so that the various programs can be run through.

Claims (11)

1. A device for dispensing over a rotary roll of a printing machine and distributing a liquid coating device formed of a printing ink or wetting agent, to a liquid pervious band which winds around the rotary roll and strips away from this excess color which falls off in a collection pool, and which liquid dispensing device renews the fluid membrane for each turn of the rotating roll, characterized in that the rotating roll (5) is aligned adjacent the pressure plate comprising cylinder (4) and transmits with the aid of the at least one around the rotating roll ( 5) orbiting stripping strip the sufficiently dosed liquid film (24) on the printing plate, and that the peripheral speed of the rotating roller (5) is practically the same as that of the printing plate cylinder (4). 2. Device according to claim 1, characterized in that the wiping belt (14) can be rolled from a brake-able shaft (15) on a drive, with a shaft (16) slidable for installing a winding angle (17). 3. Device according to claim 1, characterized in that the wiping belt (14) is realized as an endless belt (24), which preferably eats at least via a drivable roller (25), a pivotable roller and a tensionable roller (28, 30). 4. Apparatus according to claim 3, characterized in that the direction of rotation of the endless belt (24) of the moving roller (25) is freely selectable. 5. Apparatus according to claim 4, characterized in that the operation of the endless belt (24) moving the roll of the roller (8) can be steplessly controlled independently of the operation of the machine. 6. Device according to claim 5, characterized in that the endless belt (24) passes through a cleaning device (43, 44). Device according to claim 6, characterized in that the purification device (43, 44) can be pivoted away from the area of operation of the endless band (24). Apparatus according to claim 6 or 7, characterized in that it has a device (46, 47) for removing the cleaning fluid (46, 47) which is engaged in the endless belt (24). 9. Device according to any one of claims 1-8, characterized in that the wiping band (14 or 24) consists of a plastic and / or metal fabric. 10. Apparatus according to any one of claims 1-8, characterized in that the wiping band (14, 24) consists of a membrane with a uniform surface with openings (50) located over the entire wiping area, which can have any shape. Device according to any one of claims 1-8, characterized in that the wiping belt (14, 24) consists of strip strips (52, 53, 54) which are joined by bridges (5) on the side nearest the rotating roller (5). 55).