GB2346113A

GB2346113A - Roller cleaning apparatus on a rotary printing press

Info

Publication number: GB2346113A
Application number: GB0001805A
Authority: GB
Inventors: Juergen Schoelzig; Uwe Pueschel
Original assignee: MAN Roland Druckmaschinen AG
Current assignee: Manroland AG
Priority date: 1999-01-26
Filing date: 2000-01-26
Publication date: 2000-08-02
Anticipated expiration: 2020-01-26
Also published as: DE19902957C2; GB0001805D0; GB2346113B; FR2788715B1; FR2788715A1; DE19902957A1

Abstract

For cleaning a rotatable roller (1) dipping into a liquid medium and having a rastered or porous surface, an ultrasonic transducer (6) is fitted to the chamber, e.g. to the floor (5) of a chamber doctor (2). By means of this in the press, an intensive cleaning of the roller can be carried out without having to remove it from the press.

Description

2346113 ROLLER CLEANING APPARATUS OX A ROTARY PRINTING PRESS This

invention relates to roller cleaning apparatus on a rotary printing press with a chamber for receiving a liquid medium and a rotatable roller dipping into the liquid medium.

Metering devices cooperating with a rotatable roller are used in rotary printing presses for metering the feed of ink, damping agent or varnish, Known metering devices of this type are described, inter alia, in DE 43 24 631 C2 and DE 44 10 161 Al.

In metering devices of this type, there is the problem that the surface of the roller becomes contaminated in the course of operation and accordingly has to be cleaned. Such cleaning consequently requires an interruption of the printing operation and after the application of a cleaning liquid to the rotating roller, often also wiping of the roller by hand. Also, in varnishing units and in flexo printing, rollers are used, the surface of which is 2 provided with a raster. These rollers become contaminated on extended use by deposits in the depressions so that, from time to time, an intensive cleaning has to be carried out. For such an intensive cleaning, the rastered roller must accordingly be disassembled and cleaned in special cleaning plants, for example brush washing units or ultrasonic cleaning units. An ultrasonic cleaning unit is known from US 5, 291,827 A.

Furthermore, from DD 34 030, a device for cleaning printing cylinders on printing presses is known which has a suction bell which can be set against the printing cylinder in which are arranged an injection nozzle for a cleaning agent an ultrasonic emitter. The cleaning device is guided on a support and can be moved.to and fro on this in the longitudinal direction of the printing cylinder.

According to the present invention, there is provided a metering device on a rotary printing press for cleaning a rotatable roller thereof, the apparatus comprising a chamber adapted to receive a liquid medium and positioned such that the rotatable roller dips into the liquid medium in the chamber, and an ultrasonic oscillator fitted on one wall of the chamber. Such a device makes possible an intensive cleaning of the roller of the metering unit of the initially described type in the printing press with little outlay.

In accordance with the invention, an ultrasonic oscillator is fitted on one wall of the chamber of the metering device. With the aid of the arrangement of an ultrasonic oscillator in accordance with the invention, both during a printing process and also on a print interruption, the roller of the metering device can be cleaned so intensively that mechanical cleaning by hand j /___1 % or cleaning in a separate cleaning plant is not necessary. If it is a question of the metering unit in the damping unit, then by means of the operation of the ultrasonic oscillator during the printing, ink build-up on the damping ductor roller is suppressed and a constant damping agent feed achieved. If operation of the ultrasonic oscillator during the print is not possible, then it is to be seen as an essential advantage of the metering device in accordance with the invention that in the press, with little outlay of time, automatic cleaning of the roller can be carried out without any mechanical handling of the same by hand.

The configuration of the metering device in accordance with the invention is characterised furthermore by little constructional outlay since only the chamber for receiving the liquid medium has additionally to be equipped with an ultrasonic oscillator.

In accordance with a further proposal in accordance with the invention, the chamber cap be formed by a separate device equipped with an ultrasonic oscillator, e.g. a doctor, which can be set for carrying out cleaning by means of a rinsing medium against the roller. The device can, for example, be set additionally against a chamber doctor bearing in order to be able to carry out the cleaning of the roller..

The invention is explained in more detail in what follows with the aid of exemplary embodiments, which are illustrated in the accompanying drawings, in which:

Figure 1 shows a schematic illustration of a metering device with a chamber doctor in accordance with the invention, Figure 2 shows a cleaning device which can be used in 4 the place of a chamber doctor, Figure 3 shows a schematic illustration of a damping unit in accordance with the invention with roller 5 metering, and Figure 4 shows a further configuration'of a damping agent container for a damping unit in accordance with Figure 3.

Figure 1 shows a metering device which is used, for example, in varnishing stations on rotary sheet printing presses. The metering device consists of a roller 1 against which a chamber doctor 2 is set. The surface of the roller 1 is porous or provided with fine rastering and has innumerable very small depressions lying closely adjacent one another in the form of little basins. In operation, these depressions accept the liquid medium located in the chamber 3 of the chamber doctor 2, for example varnish, ink or damping agent and transfer it on to a forme cylinder 4 rolling off against the roller 1. The quantity of liquid medium transferred is, in this connection, determined by the scoop volume of the depressions in the porous or rastered surface of the roller 1. If, during the course of operation, dirt builds up in the depressions, then the scoop volume diminishes and accordingly also the quantity of liquid medium donated to the forme cylinder 4, which is undesirable. Cleaning of the surface of roller 1 is accordingly necessary from time to time, which also removes the dirt sticking in the depressions. Likewise, the roller 1 at the end of production must be cleaned on a change e.g. of the type of varnish or of the roller. In order to be able to carry out the cleaning rapidly and with the desired thoroughness, an ultrasonic oscillator 6 is fitted on a base plate 5 of the chamber doctor 2. The ultrasonic oscillator 6 is located in a /N -j depression on the outer side of the base plate 5 turned away from the chamber 3 substantially in the middle between the stripping off edges of the doctor blades 7 so that the oscillations generated are directed directly on to the surface of the roller 1. The ultrasonic oscillator 6 can consist of a single element extending in the longitudinal direction of the chamber doctor 2. However, also two or more individual elements can be arranged at a distance from one another on the base plate 5 of the chamber doctor 2.

For cleaning the roller 1, this is set in rotation and the chamber 3 of the chamber doctor 2 filled with a cleaning liquid and rinsed through. Simultaneously with the aid of the ultrasonic oscillator 6, soundwaves are generated, the frequency of which preferably lies in a region from 20 to 40 kHz. In this fashion in a short time, an effective cleaning of the roller 1 can be achieved without needing any additional measures. With the configuration described, it is additionally possible to stimulate the ultrasonic oscillator 6 during the printing process and thereby to reduce the deposition of dirt particles on the roller 1.

In place of the chamber doctor 2 for cleaning the roller 1, also the cleaning device 8 shown in Figure 2 can be used, which is used in place of the chamber doctor 2 in the chamber doctor seating 9. The cleaning device 8 consists of a box 21 which, analogously to the chamber doctor 2, surrounds a chamber 3 for receiving a liquid cleaning medium. The box 21 has an opening 22 extending in the longitudinal direction of the roller 1 which is closable by means of the roller 1 when the box 21, as illustrated in the drawing, is set against the roller 1.

The edges 23 of the opening 11 carry a seal 24 in the form of an o-ring which seals the box 21 relative to the roller 1.10n the floor of the box 21, opposite the 6 opening 22, an ultrasonic transducer 6 is fitted. The feeding and return of the cleaning medium takes place via openings 25, 26 in the end face walls of the box 21. The cleaning of the roller 1 is carried out with the cleaning device 8 in the same way as with the chamber doctor 2.

Figure 3 shows a damping unit of a rotary offset printing press. The damping unit has a roller 10 dipping into damping agent, a metering roller 11 and a damping applicator roller 12. The roller 10 takes the damping agent from a damping agent container 13 and transfers it on to the damping applicator roller 12, which is in contact with the plate cylinder 14. The metering roller 11 lying against the roller 10 takes care that an even distribution of the damping agent on the surface of the roller 10 occurs and determines the thickness of the damping agent film. As well as the damping applicator roller 12, there is a bridge roller 15 which lies against the damping applicator roller 12 and an ink applicator roller 16 of an otherwise not illustrated inking unit. The container 13 is filled via a feed lead 17 or emptied via a return lead 18 depending upon requirements with damping agent or a cleaning liquid.

During the print operation, the roller 10 dipping into the damping agent accumulates ink from the damping applicator roller 12, whereby the damping agent feed is adversely affected. In order to suppress this and to be able to clean the roller 10 during print operation, outside on the floor of the container 13, an ultrasonic oscillator 19 is fitted which can be stimulated with the aid of a generator 20. If the ultrasonic oscillator 19 is stimulated during the printing process, then the ink fed to the roller 10 is removed and ink build-up suppressed. In this fashion, a constant damping agent feed is achieved and an interruption of the printing 7 operation for cleaning the rollers avoided. Also cleaning after the printing process using a cleaning agent is substantially simplified and made faster by the use of the ultrasonic transducer 19. 5 As in the case of the exemplary embodiment in accordance with Figure 1, the ultrasonic oscillator 19, e.g. a flexible oscillator, can consist of a longitudinally extended element or several individual elements.

Furthermore, there can, as shown in Figure 4, be a plate-shaped ultrasonic oscillator 19 arranged on the inner side on the floor of the container 13 in order to achieve yet more direct action of the sound energy on the surface of the roller 10.

8

Claims

1. Apparatus on a rotary printing press for cleaning a rotatable roller thereof, the apparatus comprising a chamber adapted to receive a liquid medium and positioned such that the rotatable roller dips into the liquid medium in the chamber, and an ultrasonic oscillator fitted on one wall of the chamber.

2. Apparatus according to Claim 1 wherein the roller has a porous surface or one provided with a raster and the chamber is formed by a chamber doctor with doctor blades arranged at a distance from one another, wherein the ultrasonic oscillator is fitted between the doctor 15 blades to a floor plate of the chamber doctor.

3. Apparatus according to Claim 1 wherein the chamber is formed by a container arranged under the roller and the ultrasonic oscillator is fixed to the floor of the 20 container.

4. Apparatus according to any one of the preceding Claims wherein the ultrasonic oscillator is arranged as a flat element on the inner side of the chamber. 25

5. Apparatus according to one of Claims 1 to 3, wherein the ultrasonic oscillator is arranged on the outside of the chamber and the floor of the chamber is constructed as an oscillating membrane. 30

6. Apparatus according to one of the preceding Claims wherein the chamber is configured as a cleaning device equipped with an ultrasonic oscillator which can be set against the roller for carrying out a cleaning. 35

7. Apparatus according to Claim 6 wherein the cleaning device has a box with an opening extending along the 9 roller and the edges of the box limiting the opening can be set against the roller and carry a seal which can be laid against the roller.

8. Apparatus according to any one of Claims 1 to 5 and constructed as a metering device for damping liquid or varnish.

9. Apparatus according to Claim I and substantially as hereinbefore described with reference to the accompanying drawings.