Printing – Intaglio – Rotary
Patent
1993-12-29
1996-05-07
Bennett, Christopher A.
Printing
Intaglio
Rotary
101168, B41F 914
Patent
active
055135668
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention pertains to a rotary printing machine having a printing cylinder, pressable relative to a counter roller, which is provided with an ink supplying apparatus for supplying printing ink to the surface of the printing cylinder.
STATE OF THE PRIOR ART
Such printing machines, particularly rotogravure printing machines are described in many publications, for example, as described in Bruckmann's Handbuch der Drucktechnik, (Handbook of Printing Techniques by the Bruckmann Publishing Co.), published in Munich, in 1976.
In order to print more economically, there is a need to build wider printing machines of that type, and to increase the printing width as well as the printing speeds, that is to increase the number of revolutions of the printing cylinder. Rotary printing machines of the noted construction do not fulfill these requirements or only in a limited manner, due to the following reasons:
Printing cylinders of greater width, particularly those with a small circumference, deflect under pressure, to such an extent, that the movement of the paper is disturbed via the formation of folds. In addition, as a consequence of the deflection, the applied printing ink is no longer uniformly removed, across the entire width of the printing cylinder, by the squeegees.
The rolling element bearings of the printing cylinder become overloaded due the higher pressure loads and the higher number of revolutions, which often leads to early failure of the bearings.
The filling of the gravure wells or recesses on the surface of the printing cylinders can no longer be fully assured at the higher paper speeds, since the immersion time of the generally utilized ink containers is too short, and since, at the higher number of revolutions, the increased centrifugal force, works against the wetting by means of the printing ink.
DESCRIPTION OF THE INVENTION
The invention has the task, to avoid the previously-noted disadvantages of the prior art, and particularly, in a rotary printing machine of the initially-described type, to totally avoid or keep within limits, the deflection of the printing cylinder even at increased widths and with all utilized diameters, to relieve the bearing pressure of the printing cylinders and to assure the dependable filling of the gravure wells on the surface of the printing cylinder, with printing ink in a short time.
In accordance with this invention, this task is resolved in that the printing cylinder is supported on at least one tensioned flexible band, wherein printing ink is supplied into a gap between the band and the printing cylinder, over the surface of the printing cylinder upon the band, wherein at the same time, a hydraulic lubrication layer for the bearing means of the printing cylinder is formed upon the band.
The flexible band can extend across the entire width of the printing cylinder or the printing web, or several laterally adjacent bands are provided whereby differing printing colors can be applied, independently of each other, upon different width portions of the printing cylinder.
It is an advantage to vary the length of the flexible band with an applicable apparatus so that the wrap angle of the band about the printing cylinder can be set and the band can be accommodated to differing diameters of the printing cylinder.
It is of particular advantage to journal the ends of the printing cylinder in a machine frame, in connection with which the journals are provided with an arrangement for measuring the bearing forces. The part, over which the flexible band is tensioned, is advantageously formed as a carriage movable in the press direction within a machine frame and is pressed, via a placement apparatus that is controlled via a bearing sensor, against the pressing cylinder with such force so as to unload the printing cylinder bearings and that the force is taken up practically only through the nearly friction free and low wearing hydraulic journalling of the printing cylinder upon the flexible band. This means that the deflection forces operating in the pri
REFERENCES:
patent: 1115127 (1914-10-01), Stickney
patent: 2997951 (1961-08-01), Huck
patent: 3853698 (1974-12-01), Mohr
Lehmann Rolf
Schnyder Eugen
Bennett Christopher A.
Sulzer-Escher Wyss AG
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