DD274003A1 - RAKE DEVICE FOR OFFSET PRINTING MACHINES - Google Patents

Abstract

The invention relates to a squeegee device for offset printing machines for the automatic removal of dirt particles from the pressure plate clamped on the plate cylinder. The aim is to provide a squeegee device for offset printing machines, which contributes to the improvement of print quality. The task of providing an automatically operable and cleanable, no positioning time-requiring doctor device is achieved in that a maximum printing plate width overlapping, elastically deformable doctor blade is arranged in the space between the dampening unit and the plate cylinder. Fig. 1

Description

For this 2 pages drawings

field of use

The invention relates to a squeegee device for offset printing machines for the automatic removal of dirt particles from the pressure plate mounted on the plate cylinder.

Characteristic of the known technical solutions

When printing on offset printing machine designated at each cylinder revolution as partisans or cleaning Schmutzteilchtn, which consist of Farbparttkelchen or zusammengeschobenem paper leaves and come either from the inking unit to the plate or poorly processed papers on the blanket to Plattenzvlindor provided by the ink rollers with color, which again the blanket and on the bow is discharged.

As a result , non-printing, white zones appear on inked image areas or raster areas around the fuzzy particles, significantly affecting the print image.

In the past few years, a large number of solutions have become known in order to eliminate the risk of damage during printing of the plate cylinder .

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

The disadvantage of this device is the manual operation, whereby a significantly delayed effect occurs due to 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. The width of the squeegee corresponds to the color zone width. However, this device is generally difficult to clean, with a strong soiling occurs especially at the overlaps.

From DE-OS 2715445 a further device for removing dust or similar substances has become known.

An individual doctor blade, which can be automatically moved on a shaft, removes the dirt particles adhering to the lateral surface of the forme cylinder.

Another known device operates with a round disc doctor, which is positionable by means of pneumatic non-cylinder along the cylinder surface of the form cylinder. Both of the latter devices also have a delayed effect due to the first necessary positioning.

Object of the invention

The aim of the invention is to provide a Rakeleinrichtang for Off offset printing machines, which contributes to improving the print quality.

Essence of the invention

The object of the invention is to provide a squeegee device for offset printing machines, which is automatically operable and cleanable and requires no positioning time.

According to the invention the object is achieved in that a maximum printing plate width covering, elastically deformable doctor blade is arranged in the space between the dampening unit and the plate cylinder. The squeegee is coated on the front edge with a color-repellent elastomer. The doctor blade is arranged on a movable doctor bar, to which one actuating unit and a plurality of actuators or a rotary drive with a plurality of actuators are assigned. Furthermore, the doctor of the fountain solution application roller or the blanket cylinder can be assigned.

Exemplary embodiment «

The invention will be explained in more detail with reference to a Ausführungsbeispieies. The accompanying drawings show:

1: schematic representation of the device according to the invention in doctor blade position FIG. 2: doctor device in the washing position on the first dampening roller FIG. 3: doctor device in the washing position on the blanket cylinder.

1, a dampening unit 1 is arranged on a plate cylinder 2. The dampening unit 1 consists essentially of a in

a fountain solution box 3 dipping ductor roller 4, which via a metering roller 5 with a machine-driven

Dampening solution roller β is in communication. Immediately above the ink fountain roller β is an inking roller 7

arranged, which is also in bodily contact with the Plattenzylinde · 2. Between the fountain solution application roller 6 and the

Ink application roller 7 is a positionable and axially distributing connecting roller 8 is arranged. The squeegee device for removing dirt particles and the pressure plate mounted on the plate cylinder 2 is

below the fountain solution application roller 6, mounted in the free space between the plate cylinder 2 and dampening unit 1.

This device has a corresponding to the plate cylinder length continuous doctor bar 9, which once on the Bearing 10 is rotatably mounted in the machine frame and connected to the other with the actuating unit 11 arranged on both sides

is. Several actuators 12 are fixed to the bearing side of the doctor blade 9 in the direction of fountain solution applicator roll 6 on the

Doctor blade 9 arranged. The actuator 11 and the actuators 12 are mechanically, hydraulically, pneumatically or electrically as required

actuatable actuators.

In the doctor bar 9 is still in the direction of plate cylinder 2 an a.'e maximum printing plate width overlapping elastic

deformable doctor 13 at a small distance from the plate cylinder Ϊ clamped. The doctor blade 13 is coated at the leading edge with a color-repellent elastomer having a blade-shaped geometry. Below the squeegee bar 9 at the level of

Actuator 11 is a first adjustable stop 14 mounted in the machine frame. The mode of action is the following: If the initially described defects are detected on the printed sheet, the corresponding actuator 12 becomes zonal or

operated the actuators 17 in their entirety from the control panel. As a result, the rake! 13 in turn pressed zonal orin its entirety against the pressure plate clamped on the plate cylinder 2 and the dirt particles or the

Color build-up removed from the printing plate. Of course, a collecting container for larger color accumulations is arranged below the doctor blade 13. To clean the Doctor blade 13, the entire blade control is integrated into the automated machine control. In this case, the Rakelvordorseite is entspreohend in each washing operation of the dyeing and dampening unit or the Pluttenzylinder 2 Fig. 1 washed on the plate cylinder 2 d. H. Actuators 12 all confirmed, or the squeegee back according to Fig. 2 d. H. Actuators 12 unconfirmed. For this purpose, the control unit 11 is also actuated automatically and the entire device upwards

pivoted to a second likewise adjustable stop 15. This is guaranteed, actuators 12 course unactivated vorausgesetzt that the doctor back is applied to the parked dampening form roller 6.

A further embodiment is shown in FIG. 3. For this purpose, the squeegee 13, which is via a positionable rotary drive 16

otherwise has the same structural design as in Fig. 1, positioned in operating position in the direction of plate cylinder 2 and the dirt particles doctored in the manner described. For squeegeeing on the blanket cylinder 17, the squeegee 13 in the appropriate position, durchverschwenken order defined amount down, brought and the actuators 12 acted upon so that at the räkelnden

Place (places) lying actuator 12 (actuators 12) remains unencumbered. Washed this side of the squeegee 13 on the

switchable to the blanket cylinder 17 and integrated into the automatic washing process shown schematically

Blanket washing device 18.

Claims (6)

1. squeegee device for offset printing machines for automatically removing dirt particles from the pressure plate clamped on the plate cylinder, characterized in that one, the maximum Druckplattenbreito overlapping, elastically deformable doctor blade (13) in the space between Feuc * - 'verk (1) and the plate cylinder ( 2) is arranged. 2. Doctor device according to claim 1, characterized in that the doctor blade (13) is coated on the leading edge with a color-repellent elastomer. 3. Doctor device according to claim 1, characterized in that the doctor blade (13) on a movable doctor bar (9) is arranged, which are associated with an actuating unit (11) and a plurality of actuators (12). 4. Doctor device according to claim 1, characterized in that the doctor blade (13) is arranged on a movable doctor bar (9) to which a rotary drive (16) and a plurality of actuators (12) are associated. 5. Doctor device according to claim 1, characterized in that the doctor blade (13) of the fountain solution application roller (6) can be assigned. 6. doctor device according to claim 1, characterized in that the doctor blade (13) the rubber cylinder (17) can be assigned.