Printing – Processes – Condition responsive
Reexamination Certificate
2002-02-15
2003-09-23
Colilla, Daniel J. (Department: 2854)
Printing
Processes
Condition responsive
C101S483000, C101S365000
Reexamination Certificate
active
06622626
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method of starting up a rotary offset printing machine of the type having printing units, each printing unit having a printing plate cylinder, a rubber blanket cylinder for transferring ink from the printing plate cylinder to a web being printed, a dampening unit for dampening the printing plate cylinder, applicator rolls which can be set onto and off of the printing plate cylinder, an inking unit for applying ink to the applicator rolls, and a metering device for supplying a defined quantity of ink to the cleaned inking unit.
2. Description of the Related Art
When starting up a rotary offset printing machine, for example at the start of a new production run, the aim is to reach the operating state for continuous printing quickly, in order to keep the wastage low. With regard to the quantity of printing ink and dampening solution supplied to the printing plate, settings have to be made. The inking units of the printing units have a metering device on which passage openings for the printing ink can be adjusted zone by zone, that is to say distributed over the width of the inking unit or the printing plate. It is known to set these openings in accordance with the subject on the printing plate, that is to say in accordance with the consumption of the individual inking zones. With this setting an input of ink is carried out with the ink applicator rolls set off. An inking profile set in this way is illustrated hatched in FIG.
1
. Within the context of setting the print on, the ink applicator rolls are also set onto the printing plate, on which an ink layer or an ink density S builds up at the printing locations. The build-up of the ink density is shown in
FIG. 2
, by the dashed curve, as a function of the number of prints or copies made. The desired layer thickness or ink density S
F
for continuous printing is only established after about 1500 copies in zones with a low area coverage, and these copies have to be considered waste. In the case of the procedure described for starting up the printing machine, it is in particular disadvantageous that zones with a low ink consumption, for example zone
1
, with the low quantity of ink supplied need a very long time until the desired layer thickness on the printing locations of the printing plate is achieved. In this way, for example register marks are printed visibly only after a relatively long time has elapsed. As opposed to this, the initially plentiful supply of printing ink in an inking zone with a high ink consumption, for example in the inking zone
3
, leads to overinking of the printing areas.
EP 0 529 257 B1 sets an inverse ink profile on the ink metering device after an interruption to the printing process, such as during the daily new start after washing the rubber blanket. It is virtually the case that, in an inking zone with a low ink consumption, an exaggeratedly high amount of ink is supplied to the inking unit, and in an inking zone with a high ink consumption, exaggeratedly little ink is supplied to the inking unit. In this case, the ink applicator rolls are set on, in order in addition to permit the subject on the printing plate to have a back effect.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a method of starting up a rotary offset printing machine in which the continuous printing state can be reached quickly and with little accumulation of waste.
According to the invention, the method includes the following steps
setting an inking profile on the metering device which is the inverse of an inking profile for continuous printing,
metering a defined quantity of ink to the cleaned inking unit according to said inverse profile with the applicator rolls set off the printing plate cylinder and the machine operating at a first rotational speed,
accelerating the machine to a second rotational speed,
accelerating the machine from the second rotational speed to a third rotational speed,
pre-dampening the rubber blanket cylinder,
setting the inking profile to the profile for continuous printing while the machine is being accelerated from the second rotational speed to the third rotational speed, and
executing a print on sequence when the third rotational speed is reached.
By virtue of the well coordinated method steps, only very little wastage is produced by the time the continuous printing state is reached.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.
REFERENCES:
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patent: 5784960 (1998-07-01), Gensheimer et al.
patent: 5845574 (1998-12-01), Dilling et al.
patent: 5907999 (1999-06-01), Lusar et al.
patent: 6006664 (1999-12-01), Hummel et al.
patent: 6109177 (2000-08-01), Wech et al.
patent: 6318260 (2001-11-01), Chu et al.
patent: 6477954 (2002-11-01), Doherty
patent: 0 529 257 (1993-03-01), None
patent: 529257 (1993-03-01), None
patent: 2 312 186 (1997-10-01), None
patent: 2328903 (1999-03-01), None
patent: 2001246733 (2001-07-01), None
Stuhlmiller Helmut
Zeller Reinhard
Cohen & Pontani, Lieberman & Pavane
Colilla Daniel J.
Man - Roland Druckmaschinen AG
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