DD281149A5 - DEVICE FOR REMOVING POWERS IN MULTICOLOR PRINTING MACHINES - Google Patents

Abstract

The invention relates to a device for removing slugs in multi-color printing presses by means of an engageable on the plate or blanket cylinder of each printing unit doctor device. The aim of the invention is a device for eliminating slugs in multi-color printing machines, so as to contribute to reducing the waste content. The object of providing a device for removing slugs in multi-color printing machines with which the detection, localization and removal of the slugs is carried out independently of the operating personnel is achieved by assigning to each printing unit a sensor linked to the doctor device. FIG {multicolor printing machine; slugs; Doctor device; Sensor}

Description

For this 1 page drawing

Field of application of the invention

The invention relates to a device for removing slugs in multi-color printing presses by means of an engageable on the plates or blanket cylinder of each printing unit doctor device.

Chsrakterlstik the known prior art

When printing on offset printing machines designated as slugs at each cylinder revolution dirt particles, which consist of Farbpartikelchen, pushed together paper dust or stroke and come either from the inking unit to the plate or bad verart siteten papers on the blanket to the plate cylinder, provided by the ink rollers with color, which again is delivered to the blanket and on the sheet.

As a result, non-printing, white zones develop on inked image areas or raster areas around the dirt particles, whereby the printed image is substantially impaired.

To eliminate these debris during printing from the plate cylinder, a variety of solutions have become known in recent years.

DE-AS 1146506 discloses a device for removing these dirt particles, with a manually engageable on the lateral surface of the forme cylinder, parallel to the forme cylinder axis movable spatula.

The disadvantage of this device is the manual operation, whereby a significantly delayed effect eintiitt by the first necessary positioning.

Another known in practice solution are single blade over the plate cylinder width overlapping arranged and individually adjustable by pneumatic cylinder. However, this device is generally difficult to clean, with a strong soiling occurs especially at the overlaps.

By DE-OS 2715445 another device for removing dust or similar substances has become known.

An automatically displaceable on a while single blade removes the adhering to the outer surface of the forme debris.

Another known device operates with a round disc wheel, which can be positioned by means of pneumatic linear cylinder along the mold cylinder jacket surface. These devices also suffer from the disadvantage of all squeegee devices disclosed in the prior art which consist in placing high demands on the printer with regard to experience and time required for the detection, localization and removal of the contamination.

Object of the invention

The aim of the invention is a device for eliminating slugs in multi-color printing machines, so as to contribute to reducing the waste content.

Explanation of the essence of the invention

The object of the invention is to provide a device for removing slugs in multi-color printing machines, whereby the identification, localization and removal of the slugs takes place independently of the operating personnel. According to the invention, the object is achieved in that each printing unit is associated with a sensor associated with the doctor device and that the sensor is arranged either in the immediate vicinity behind each or behind the last printing zone or in the delivery. The sensor is designed as a CCD camera, which compares the actual image temporarily with the target image and activates the squeegee device at the relevant location of the fault found in the difference signal.

embodiment The invention will be explained in more detail below using an exemplary embodiment. The accompanying drawing shows the

Inventive device within a printing machine in a schematic representation. Shown are two printing units and the delivery. Ausgehond of the sheet guiding cylinder 1 is the print. Sheet passed to the impression cylinder 2, wherein in the contact zone between the impression cylinder 2 and the Gummizylinaer 3 follows the printer. The Plaüenzylinder 4, which transmits the printed image on the blanket cylinder 3, is colored by the inking unit 5. The moisture is carried by the

Dampening 6. About the sheet guiding cylinder 1.1, the sheet is fed to the subsequent printing unit, wherein

again in the contact zone pressure cylinder 2.1 -Gummizylinder 3.1 the pressure of the next color takes place.

The Auslagetrornmol 7 passes the printed sheet a Greiferausiagesystem which the bow on the Auslegestapel

promoted. The squeegee device 8 for removing dirt particles on the spanned on the plate cylinder 4

Pressure plate is located below the dampening unit 6, in the free space between Piattenzylinder 4 and dampening unit 6. This doctor device 8 is known according to the DD application number WP B41F 317791.6 and therefore not

described in more detail.

This doctor device 8 is z. B. on pneumatically moved mechanisms for plate cylinder 4 and the rubber cylinder. 3

on and off.

After the printing zone of each printing unit are in the immediate vicinity of the printing cylinder 2,2,1 one or more Sensors 9, which traversierend or firmly the one or more color printed sheet touches. The sensor 9 is constructed so that via a CCD camera, the print image during the machine run line by line and column

for column, i. Known pixel by pixel and compared with the reference to the target-actual-value comparison in a computer stored reference sheet. The reference sheet can be proof sheet. With the help of this

Monitoring device becomes the location, i. H. the printing unit and the color zone in which the pollution (slug) is located

analyzed exactly. Starting from this sensor 9 is now in the relevant printing unit and in the appropriate color zone the

Rakeleirrichtung 8 for removing the Butzens on the plate cylinder 4,4.1 driven. Will this slug be within a

certain period of time is not eliminated, i. Sensor 9 signals no trouble-free continuous printing sheet, so the pivots

Doctor device 8 automatically for a certain time unit to the blanket cylinder 3,3.1 and tries on the blanket

eliminate the cause of the disturbance of the printed image. Subsequently, the doctor device 8 pivots back into their

Starting position back. Another way to automatically remove slugs is to just one sensor 9 behind the last one Pressure zone or in the display 10 to order. This low cost of electronic components but is the Disadvantage against the fact that more time is needed for the removal of pollution, because although the true color zone

is detected, but not the printing unit. By means of a sequential circuit, all of them must occur consecutively when slugs occur

Printing units or plate cylinder are controlled until a trouble-free run is signaled. Despite this disadvantage is

to view this sensor order as a cost-effective compromise. Needless to say, the sensors are for locating

Pressure disturbances in the form of slugs suitable for other tasks, such as ι. B. Measurement of color density in solid areas and Raster tone areas and the determination of the print contrast.

Claims (4)

1. A device for Besaitigen slugs in multi-color printing machines by means of an engagable on the plates or blanket cylinder of each printing unit doctor device, characterized in that each printing unit associated with the doctor device sensor (9) is associated. 2. Device according to claim 1, characterized in that the sensor (9) is arranged in the immediate vicinity behind each or behind the last print zone. 3. Device according to claim 1, characterized in that the sensor (9) in the delivery (10) is arranged. 4. Device according to claim 1, characterized in that the sensor is designed as a CCD camera which compares the actual image line by line with the target image and activates the squeegee device at the relevant location of the fault found in the difference signal.