GB2333265A

GB2333265A - Process for operating a rotary offset printing press

Info

Publication number: GB2333265A
Application number: GB9900945A
Authority: GB
Inventors: Alexander Kluh; Hans-Martin Reinert
Original assignee: MAN Roland Druckmaschinen AG
Current assignee: Manroland AG
Priority date: 1998-01-17
Filing date: 1999-01-15
Publication date: 1999-07-21
Anticipated expiration: 2019-01-15
Also published as: GB2333265B; DE19801623B4; JPH11254651A; FR2773739A1; FR2773739B1; DE19801623A1

Abstract

For filling the inking unit during an ink run-in phase preceding the printing, or for emptying the inking unit in a rotary offset printing press with a separately driven ink fountain roller (1) dipping into an ink fountain (2), a controlled ink ductor roller (3), and an inking roller train with an ink take-off roller (4) cooperating with the ink ductor roller (3), it is provided that the ink ductor roller (3) is brought into contact simultaneously with the ink fountain roller (1) and with the ink take-off roller (4). Hereby, the duration of the ink run-in phase or of the emptying of the inking unit is shortened.

Description

2333265 PROCESS FOR OPERATING A ROTARY OFFSET PRINTING PRESS This

invention relates to a process for operating a rotary offset printing press with a separately driven ink fountain roller dipping into an ink fountain, a controlled ink ductor roller, an ink roller train with an ink take-off roller cooperating with the ink ductor roller and a device by which the ink ductor roller can be brought simultaneously into contact with the ink fountain roller and the ink take-off roller.

An offset printing press of this type is known from DE 44 24 590 Al. In this connection, the operational position is provided in which the ink ductor roller is simultaneously in contact with the ink fountain roller and the ink take-off roller, for cleaning the inking unit with the aid of a cleaning liquid fed to the inking unit in order to achieve that the ink fountain roller and the ink ductor roller are cleaned in a single operational pass together with the fu rther inking unit roller train.

The invention relates to another problem. On the beginning of production or on a change of order, it is first necessary to take the press through an inking runup programme in order to achieve the filled condition of the inking unit which is required for the beginning of printing. Depending upon the delaying action of the ink ductor roller alternately in a preset ribbon in contact with the ink fountain roller or the ink take-off roller, the inking run-in programme extends to an operational time of several hundred press revolutions until finally all layer thicknesses in the inking unit are substantively the same and one can start printing. This requirement on time is disadvantageous from an economic point of view, above all when frequent order changes occur.

The object underlying the invention is to provide a process for operating a rotary offset printing press of the initially noted type which makes possible a short ink run-in phase.

In accordance with the invention, this problem is solved in that for filling the inking unit during an ink run-in phase preceding the print, the ink ductor roller is brought into contact simultaneously with the ink fountain roller and with the ink take-off roller. By generating, in accordance with the invention, a closed roller train between the ink fountain roller and the remaining rollers of the inking unit, the filling time of the inking unit is substantially shortened, since substantially less press revolutions suffice in order to achieve the desired defined condition for print starting. Also the emptying of the inking unit, e.g. for an ink change, can, in accordance with a further proposal of the invention, be substantially accelerated if, for this, the roller train is connected to the ink ductor roller.

The invention is described in more detail subsequently with reference to an exemplary embodiment of an inking unit of a rotary offset printing press diagrammatically illustrated in the accompanying drawing.

Referring to the drawing, a roller inking unit is illustrated, in which ink is applied on to the surface of an ink fountain roller 1 from an ink fountain 2 in the form of a defined ink film. An ink ductor roller 3 takes ink off from the ink fountain roller 1 and transfers this on to an ink take-off roller 4. Arranged downstream relative to the ink take-off roller 4 is a roller train consisting of several intermediate rollers 5, a branching roller 6, several transfer rollers 7, 8 and several ink applicator rollers 9. The ink applicator rollers 9 feed the ink finely distributed to a plate cylinder 10 in order to ink up the printed image located on this. A blanket cylinder 11 transfers the inked-up printed image on to a not illustrated printing surface.

Also fitted to the plate cylinder 10 is a damping unit of which a damping agent container 12, a damping ductor 13, a metering roller 14, a damping applicator roller 15 and a bridging roller 16 are illustrated.

The ink ductor roller 3 is rotatably mounted at its ends in the ends of two levers 17 which are swivellable about a common swivel axis 18 and which, with the aid of a swivel drive 19, can carry out a to and fro oscillating movement. Additionally to this, the swivel axis 18 is adjustable in the longitudinal direction of the lever 17 to such an extent that the ink ductor roller 3 can be moved between the position illustrated by a full line, where roller 3 is in contact with ink fountain roller 1 and ink take-off roller 4, and the position illustrated dashed from which it can be reciprocated to contact each of rollers 1 and 4 alternately. A possible construction of such a mounting for the ink ductor roller 3 is described in DE 44 24 590 Al.

For rapid filling of the inking unit at the start of production or after a change in order. the ink ductor roller 3 is brought into the position illustrated in the full line in the drawing in which it is in ink transferring contact with the ink fountain roller 1 and the ink take-off roller 4. Additionally, the swivel drive 19 is rendered stationary and the rotational speed of the ink fountain roller 1 preferably matched to the press rotational speed, either by suitable control of the separate drive of the ink '.)untain roller 1 or by decoupling the ink fountain roller 1 from its drive and letting it be driven by means of friction via the ink ductor roller 3 and the subsequently arranged roller train. Because of the closed roller train formed in this fashion from the ink fountain roller 1 up to ink applicator rollers 9, a rapid filling of the inking unit with ink is achieved so that already after a substantially shorter time, in comparison to the time which would have elapsed if the to and fro moving operation of the ink ductor roller 3 had been maintained, the layer thicknesses in the inking unit necessary for the print start are achieved. For the subsequent beginning of printing, by adjustment of the swivel axis 18, the ink ductor roller 3 is brought into the dashed position, and by switching on the swivel drive 19 moved to and fro, so that it then comes into contact alternately with the ink fountain roller 1 and the ink take-off roller 4.

If the inking unit has to be emptied on an ink change, - then this process can be accelerated, just as likewise on filling up the inking unit, by adjusting the ink ductor roller 3 to form a closed roller chain.

In place of moving the ink fountain roller 3 in a closed roller train for accelerating the ink run-up, the same effect can also be achieved by fixing the ink ductor roller 3 and adjusting the position of the other roller 4 or 1 respectively.

Claims

1. A process for operating a rotary offset printing press, the press including a separately driven ink fountain roller dipping into an ink fountain, a controlled ink ductor roller, an ink roller train with an ink take-off roller cooperating with the ink ductor roller and means enabling the ink ductor roller to be brought simultaneously into contact with the ink fountain roller and the ink take-off roller, wherein for filling the inking unit during an ink run-in phase preceding printing, the ink fountain is filled with ink, the ductor roller is brought simultaneously into contact with the ink fountain roller and with the ink take-off roller, and all of the rollers rotated to distribute the ink over all of them.

2. A process for operating a rotary offset printing press, the press including a separately driven ink fountain roller dipping into an ink fountain, a controlled ink ductor roller, an inking roller train with an ink take-off roller cooperating with the ink ductor roller and the ink ductor roller to be brought simultaneously into contact with the ink fountain roller and the ink take-off roller, wherein for emptying ink from the inking unit, the ink ductor roller is brought into contact simultaneously with the ink fountain roller and with the ink take-off roller, all of the rollers are rotated, and ink is thereby fed from the ink fountain and received from a roller downstream of the ink fountain.

3. A method for operating a rotary offset printing press in accordance with Claim 1 or 2 and substantially as hereinbefore described with reference to the accompanying drawing.