Printing – Planographic – Rotary machines
Reexamination Certificate
2000-12-18
2002-10-01
Colilla, Daniel J. (Department: 2854)
Printing
Planographic
Rotary machines
C101S247000
Reexamination Certificate
active
06457407
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a method for adjusting cylinders in a printing machine, and to a printing machine suitable for performing the method.
Modern in-line sheet-fed offset rotary printing machines include a plurality of offset printing units and often a varnishing or lacquering unit downline from the offset printing units, and are thus set up as effectively as possible for the widest possible variety of printing jobs. Many of the printing jobs, although indeed requiring print carrier sheets to be printed in the printing units, do not need any varnishing of the sheets in the varnishing unit. The applicator cylinder of the varnishing unit is therefore thrown off from the impression cylinder for the printing jobs. In this adjustment of the applicator cylinder from a print-on position into a print-off position, a printing nip formed by the cylinders is opened slightly. When the sheets are being transported through this slightly opened printing nip, there is a risk that the sheets transported past the applicator cylinder on the impression cylinder will engage or impact the applicator cylinder, with the result that fresh ink applied to the sheets in the printing units becomes smeared onto the applicator cylinder.
It is therefore desirable for the printing nip between the impression cylinder and the applicator cylinder to be capable of being enlarged to such an extent that there is no longer any risk of the sheets impacting the applicator cylinder. This desire is often obstructed, however, by the fact that various components are arranged in the immediate vicinity of the applicator cylinder, such as, for example, the impression cylinder, a supply roller for supplying ink or varnish to the applicator cylinder, a blower for guiding the sheets, a washer for cleaning the applicator cylinder and a varnish bath or tub for storing the varnish printed by the applicator cylinder, and impede wide-ranging displacements of the applicator cylinder. Consequently, as a rule, it is possible for the applicator cylinder to be displaced out of the print-on position thereof into the print-off position thereof only over a short distance, with the result that the clearance between the applicator cylinder and the impression cylinder is not large enough.
In order to overcome this problem and prevent the sheets from impacting the inactive applicator cylinder, various possibilities are conceivable, some of which are explained briefly hereinbelow.
A first possibility would involve a simultaneous midpoint displacement of the applicator cylinder and the supply roller away from the impression cylinder, so that the printing nip is enlarged to a sufficient extent. However, a relatively complex adjustment mounting would be necessary for coupling the applicator cylinder to the supply roller in order to maintain permanent bearing contact of the applicator cylinder with the supply roller during the simultaneous displacement.
A second possibility would involve withdrawing away from the applicator cylinder, those components, such as the varnish bath or tub, the washer, and the blower, for example, which block the sufficiently wide displacement of the applicator cylinder, so that the applicator cylinder can be pivoted coaxially to the supply roller, in a direction of rotation corresponding to the direction of rotation of the impression cylinder during the transport of the sheets, into the free space resulting from the withdrawal. However, not every printing machine has sufficient free space for the withdrawal of the aforementioned components, and the bearing supports necessary for withdrawing the components are relatively costly.
A third possibility would be to remove the applicator cylinder not required for the current in-line process from the varnishing unit, so that the print carrier printed in the offset printing units can run through the varnishing unit without difficulty. However, a selective operation of the printing machine without the applicator cylinder presupposes specific constructive conditions. So that, with the applicator cylinder removed from the printing machine, the gearwheel arranged coaxially with the applicator cylinder for rotatively driving the latter can remain integrated as an intermediate wheel in a gear train of the printing machine, it is necessary to have a coupling for decoupling the applicator cylinder from the gearwheel remaining in the printing machine, and for coupling the applicator cylinder to the gearwheel when the latter is subsequently reinserted into the printing machine. For example, the coupling for separating and connecting an axle journal or kingpin could be arranged on this axle journal at the drive-side end of the applicator cylinder. After the separation of the axle journal, a journal part thereof, together with the gearwheel seated on this journal part and with a roller bearing for rotating the applicator cylinder, the journal part being inserted into the roller bearing, remains in the printing machine, while the applicator cylinder, together with the other journal part, can be removed from the printing machine. A coupling half of the coupling is located on each of the two journal parts. In order mutually to couple and decouple two journal parts of an applicator-cylinder axle journal arranged at the operating-side end of the applicator cylinder, a further coupling would be necessary. Thus, with the applicator cylinder removed, a journal part of the operating-side axle journal, together with an operating-side roller bearing of the applicator cylinder, could also remain in the printing machine.
It would therefore be necessary for the axle journals of the applicator cylinder to have a coupling constructed in a manner similar to that of the axle journals of a numbering shaft described in the published German Patent Document DE 34 07 681 C2. The coupling thereof is formed of a halfshell, a clamping jaw and a clamping screw/bayonet lock and is illustrated in
FIG. 4
of this reference.
Although the construction outlay resulting from the coupling for the applicator cylinder would possibly yet be justifiable, it would be necessary, because of the great weight of the applicator cylinder, to have, in order to remove it, a pivoting device which would be constructed in accordance with the pivoting device identified by the reference numeral
20
in the just-mentioned published German patent document, and the construction thereof would therefore be too complicated.
In order to prevent the sheets transported past the applicator cylinder by the impression cylinder from impacting the applicator cylinder, there is, in addition to the three possibilities explained above, a fourth possibility which is described in the published German Patent Document DE 197 19 624 C1, which describes a method for adjusting a cylinder, wherein a cylinder gap of the applicator cylinder thrown off from the impression cylinder is oriented in a manner that the cylinder gap is directed towards the impression cylinder, with the result that an enlarged interspace is produced between the cylinders. Moreover, a sheet guide element is arranged in the cylinder gap, in order to press the sheets onto the impression cylinder. In order to integrate the sheet guide element into the cylinder gap, sufficient free space is required in the latter, which is generally not available, because blanket tensioners arranged in a cylinder gap take up a very large amount of construction space for themselves.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention, therefore, to provide a method for adjusting a cylinder, by which an applicator cylinder can be adjusted in an uncomplicated manner to a sufficiently enlarged clearance relative to an impression cylinder, and to provide a printing machine by which the method can be performed, without requiring a sheet guiding element in the cylinder gap of the applicator cylinder.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a method for adjusting a cylinder in a p
Leib Rodolf
Stephan Günter
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Locher Ralph E.
Stemer Werner H.
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