JPH0346308B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a device for dampening and inking a plate cylinder, comprising an inking roller and a dampening fluid delivery roller, and a device for interrupting the supply of dampening fluid. This article relates to an offset rotary printing press.

According to West German Patent Application No. 1923475, the original roller,
A device is known for bringing the rollers of a dampening device of the type consisting of a metering roller, an intermediate roller and a plurality of applicator rollers into contact and away from each other, this known device having a switching device which can be operated via a lever. have,
The purpose is to prevent ink from entering the dampening solution from the plate cylinder.

As is well known, the uniformity and thickness of the ink film formed in an inking device used in an offset rotary printing press is largely determined by the number of rollers used and, therefore, the number of locations on which the ink film is leveled.
That is, by leveling the ink film using a roller, the ink film is made thin and uniform. The more times the ink film is leveled, the thinner and more uniform the ink film becomes. Therefore, in offset rotary printing presses, the conventional method has been to increase the number of inking device rollers to increase the number of ink film leveling points and to make the ink film uniform and sufficiently thin. was. This is because making the ink film uniform is to avoid printing mottling (uneven density on the printed surface). However, increasing the number of inking unit rollers is undesirable because it requires high construction costs and additional space.

It is therefore an object of the invention to make the ink film sufficiently thin and uniform without increasing the number of inking device rollers.

In order to achieve this objective, the configuration of the present invention includes:
With a control unit that can synchronize with the rotation of the plate cylinder,
A device for interrupting the supply of dampening liquid can be controlled in relation to the print image length of the printing plate clamped to the plate cylinder, viewed in the circumferential direction of the plate cylinder, so that the dampening liquid supply can be interrupted after dampening the print image. The supply of liquid can be interrupted, and the area of the printing plate which is not to be printed is inked by the inking roller with the supply of dampening liquid interrupted.

According to the invention, by interrupting the supply of dampening liquid in the area of the printing plate which does not have a printed image on the printing plate, the area of the printing plate which does not have a printing image of the printing plate is inked by the inking roller, i.e. The ink layer is additionally leveled between the area of the printing plate which does not have a printed image and the ink applicator roller. Furthermore, since the blanket cylinder and the plate cylinder are always in contact with each other, ink is transferred from the area of the printing plate where there is no printed image on the printing plate to the area of the blanket cylinder surface where the printing image of the printing plate is not transferred. Leveling of the ink film is also carried out between the plate and the area of the printing plate where there is no printed image and the area of the blanket cylinder surface where no printed image is transferred. This allows the
The leveling area of the ink film is thus increased without requiring high construction costs and additional space, so that the ink film is sufficiently thin and uniform.

A further advantage of the invention is that, by interrupting the supply of dampening liquid in areas where printing is not carried out, undesirable ingress of dampening liquid into the inking device is avoided.

Advantageous embodiments of the invention are defined in claim 2.
It is described below.

Next, embodiments of the present invention will be specifically described using the drawings.

FIG. 1 shows a device for dampening and inking a forme cylinder 1, which comprises inking rollers 2, 3, 4 and a dampening fluid transfer roller 10. Three ink forming rollers 2, 3, 4 are on the plate cylinder 1
One of these, the ink applicator roller 4, is also used for supplying dampening liquid, for example water. A dampening fluid delivery roller 10 is therefore connected to the inking roller 4, which is also used for supplying dampening fluid. The device for moistening and inking the forme cylinder consists in the illustrated embodiment of two ink trains.
The inking rollers 2 and 3 are connected to an inking device roller 5 in the form of a kneading mechanism, which inking device roller 5 is connected to an inking device roller 6 as an intermediate roller. The inking train has an inker roller 4, an inker roller 7 connected to the inker roller 4, and an inker roller 8. Both ink rows and are supplied with ink from an ink fountain 9 via further inking device rollers.

The supply of dampening liquid takes place via a dampening liquid transfer roller 10 (preferably a chrome roller) and an inking roller 4 connected to this dampening liquid transfer roller. The dampening liquid is brought to the dampening liquid transfer roller 10 from a dampening liquid container 12, for example a water tank, via a source roller 11 arranged in this dampening liquid container.

In the illustration and example, the printed image extends from point A to point B around the forme cylinder 1. Therefore, no printing takes place in the surface area between points B and C on the periphery of the forme cylinder 1, as well as in the groove area between the periphery points C and A. The printed image located between points A and B on the circumference of the forme cylinder 1 is moistened and inked in a known manner by inking rollers 4, 3 and 2 due to the rotation of the forme cylinder 1.

According to the invention, the supply of dampening liquid is interrupted at the latest when point B around the circumference of the form cylinder is reached, so that the form cylinder surface area B-C is no longer dampened. By interrupting the supply of dampening liquid and applying ink to the surface area B-C of the plate cylinder using at least one of the ink applicator rollers 2, 3 and 4, the surface area B-C of the plate cylinder can also be inked. A leveling of the ink film is additionally carried out. FIG. 3 shows the control circuit of the device for chronologically precise control of the supply of dampening liquid. The device for controlling the supply of dampening liquid has hydraulic cylinder/piston units 13 arranged on each end side of the dampening liquid delivery roller 10, these hydraulic cylinder/piston units 13 having a directional control function. Controllable via valve 14. In a conventional pressure generator 15, the hydraulic power necessary for controlling the hydraulic cylinder/piston unit is generated. The directional control valve 14 is adapted to be actuated via a control unit 16. By means of a control plate 17 belonging to the control unit 16 and arranged on a so-called rotational axis (not shown) and rotating synchronously with the forme cylinder 1, an advantageously contactless detection device or switch 18 can be detected.
A signal at the end of the print image at point B and a signal at the start end of the print image at point A are given to . This means that in a simple manner, a cutout B corresponding to the sector section B-A without printing of the cylinder 1 on the control plate 17
This is possible by providing -A. In this case, when the starting end of the notch (point B) is confirmed, the dampening fluid delivery roller 10 is transferred to the hydraulic cylinder/piston unit 13 based on the operation of the directional control valve 14.
As a result, it is separated from the inking roller 4 in a timely and accurate manner to the position shown by the broken line. After passing through the recess B--A, the dampening fluid transfer roller 10 is again brought into contact with the inking roller 4 at the latest at point A. By reducing the notch B-A in the control plate, the contact of the dampening fluid delivery roller 10 against the inking roller 4 during passage through the drum structure is ensured.
In other words, the printing is performed before the starting edge (point A) of the printed image.

It is also advantageously possible to shift point B on control plate 17 forward in time with respect to point B on printing plate 21. By means of this measure, the dampening by the inking roller 4 is completely interrupted behind the point B on the printing plate 21. The temporal shift of point B of control plate 17 with respect to the point of printing plate 21 is effected by appropriate rotation of control 17.

Instead of the control unit 16 shown in FIG. 3, a control unit in the form of an electronic calculator can also be used, in which case the electronic calculator stores individual angular values which are read out synchronously with the rotation of the plate cylinder. It has been done. By means of a suitable program, for example by inputting values corresponding to the length of the printing task to be printed, the positional or Time-accurate transmission occurs. In this case, plate cylinder 1
By inputting a suitable value corresponding to the length of the printing plate 21 that is tightened or the length of the printed image present on this printing plate (printing task length), the time interval at which the supply of dampening fluid should be interrupted can be determined. Specified in advance. In contrast to such a control unit, in the embodiment shown in FIG. 3 it is necessary to use one control plate 17 for each printing task of different length to be printed. That is, if the printing task lengths are different, it is necessary to use different control plates with cutouts of different sizes or to use a control plate with variable cutouts.

When printing on a thin printing carrier, the impression cylinder 2
0 is substantially always in contact with the rubber cylinder 19. In this case, the surface area of the impression cylinder 20 corresponding to the non-printing area of the plate cylinder 1 and the blanket cylinder 19 is inked by the non-printing area of the blanket cylinder 19, and also between these surface areas. The ink film is leveled.

The inking rollers 2, 3 and 4 can be separated from the form cylinder 1 by means of an eccentric member or a hydraulic cylinder-piston unit, as indicated by the reference numeral 22.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of the dampening and inking device in contact with the plate cylinder, FIG. 2 is a schematic exploded view of the plate cylinder, and FIG. FIG. 3 is a diagram showing a control circuit. 1... Plate cylinder, 2, 3 and 4... Inking roller, 5, 6, 7 and 8... Inking device roller, 1
0... Dampening liquid delivery roller, 11... Original roller, 12... Dampening liquid dispenser, 13... Hydraulic cylinder/piston unit, 14... Directional control valve, 1
5...Pressure generator, 16...Control unit, 17
...Control board, 18...Switch, 19...Rubber cylinder, 20...Impression cylinder, 21...Print plate.

Claims (1)

[Claims] 1. Offset rotary printing having an inking roller and a dampening liquid delivery roller, a device for dampening and inking the plate cylinder, and a device for interrupting the supply of the dampening liquid. In the machine, a control unit 16 that can be synchronized with the rotation of the plate cylinder 1 causes a device for interrupting the supply of dampening liquid to adjust the printing image length of the plate clamped to the plate cylinder 1 in the circumferential direction of the plate cylinder 21. Sa (A-B)
The supply of the dampening liquid can be interrupted after the printing image has been dampened, and the area (B-C) where no printing is performed on the printing plate 21 is the area where the dampening liquid is supplied. An offset rotary printing press characterized in that ink is applied by an inking roller with interruptions in the printing process. 2. An offset rotary printing press according to claim 1, wherein the separated inking roller is maintained in contact with the inking device roller 5 that supplies ink. 3. The offset rotary printing press according to claim 2, wherein the inking roller separated from the plate cylinder is capable of linear reciprocating motion in contact with the inking device roller 5. 4. An offset rotary printing press according to claim 1, wherein the ink supply is carried out via two roller rows. 5. An offset rotary printing press according to claim 4, wherein the inking rollers 4 of one of the roller rows are capable of supplying dampening fluid. 6. An offset rotary printing press according to claim 1, wherein the dampening liquid can be supplied to the inking roller 4 via a releasable dampening liquid delivery roller 10. 7. An offset rotary printing press according to claim 6, wherein the dampening fluid delivery roller 10 can be separated before reaching the end of the printed image in time. 8. The offset rotary printing press according to claim 6, wherein the dampening fluid delivery roller 10 is a chrome roller. 9. Offset according to claim 6, in which the device for separating the dampening liquid delivery roller 10 is controllable by means of a control plate 17 which rotates synchronously with the plate 1 and is detected by a feeler. Rotary printing press. 10. An offset rotary printing press according to claim 6, wherein the device for separating the dampening fluid delivery roller 10 is controllable by a microprocessor synchronous with the printing plate 1.