Printing – Inkers – Fountains
Reexamination Certificate
2001-04-26
2003-09-02
Funk, Stephen R. (Department: 2854)
Printing
Inkers
Fountains
C101S367000, C118S261000
Reexamination Certificate
active
06612238
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to an inking unit in a printing machine, the inking unit being embodied as vibrator-less continuous-type inking unit and having an ink duct or fountain with an ink duct film inserted between an ink metering system, which is subdivided into ink zones, and an ink duct roller.
In the published German Patent Document DE 199 14 179 A1, an ink duct of this type has been described having an ink duct film which is pressed against an ink duct roller by support struts of metering elements of the ink metering system; consequently, the ink duct film is subjected to high mechanical stress. In order nevertheless to assure a long service life of the ink duct film, the latter ink fountain film is provided with low-wear zones formed as wirelike bodies. Although abrasion of the low-wear zones is less than for zones of high wear, nevertheless, the production costs for such an ink duct film are comparatively high. It would be desirable, instead of this complicated, expensive ink duct film, to be able to use a simpler, less expensive ink duct film formed as a disposable item. Each time residual ink remains in the ink duct, and the ink duct film is replaced by another printing ink to be used for a subsequent printing job, it is convenient to throw the ink duct film away and insert a fresh ink duct film into the ink duct. Considering how often ink changes must be made, however, this is feasible only if inexpensive ink duct films can be used.
Furthermore, the published German Patent Document DE 38 04 204 C2 describes a continuous-type inking unit which has an ink duct roller disposed in an ink duct that is equipped with a zonewise regulatable metering system. An unfavorable aspect of this continuous-type inking unit is that cleaning it is tedious; all the residual ink in the ink duct must be removed therefrom with time-consuming labor, using a spatula and cloths. The continuous-type inking unit is therefore suitable only for a roller-type printing press as shown in the last-mentioned German patent document, wherein the interval between cleanings of the ink duct is quite long, because ink is changed only seldom in roller-type printing presses.
Also representing a further state of the art is a vibrator-type inking unit of a sheet-fed printing machine, which is described in the published German Patent Document DE 32 03 500 C3; this inking unit has an ink duct with an ink duct film and an ink duct blade or knife that is subdivided into tongues with scraper edges, for zonal ink metering. Relative to the jacket surface of the ink duct roller, each of the tongues can be set to an open metering gap corresponding to the ink demand in the respective ink zone, and in ink zones not requiring ink, each tongue can be set to a uniform basic position, i.e., a closed zero position. Each tongue set to the basic position presses the ink duct film against the ink duct roller with an initial tension or pretensioning. The pretensioning is due to the assembly operation, wherein each scraper edge, without the ink duct film being in place, is adjusted to a precise amount relative to the jacket surface of the ink duct roller, this amount being equivalent to approximately 50% of the film thickness. In addition, the ink duct film has a smooth and hard surface. Although wear of the ink duct film caused by abrasion by the ink duct roller in the printing operation can possibly be reduced slightly by suitable adjustment of the uniform basic position and by the development of the film surface, nevertheless, the wear cannot be sufficiently prevented in the manner described. The incident wear is admittedly compensated for somewhat by the elasticity of the ink duct film, but the resultant change in the pretensioning causes metering imprecisions because, as the initial tension or pretension lessens because of the pressure head or dynamic pressure of the ink inside an ink zone that intrinsically is kept closed, ink is nevertheless fed between the ink duct roller and the ink duct film and out of the ink duct.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention, therefore, to provide an inking unit of the type described at the introduction hereto, which allows simpler, less expensive ink duct films to be used.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, in a printing machine, an inking unit formed as a vibrator-less continuous-type inking unit, comprising an ink duct with an ink duct film inserted between an ink metering system, which is subdivided into ink zones, and an ink duct roller, the ink duct film within each of the ink zones in a region of a settable metering gap being held out of contact with the ink duct roller during printing.
In accordance with another feature of the invention, the inking unit includes a film roller, the ink duct roller and the film roller together defining a film nip therebetween, the width of which remains constant during printing.
In accordance with a further feature of the invention, the ink duct film rests on a base of the ink duct, and the base covers the ink metering system.
In accordance with an added feature of the invention, a central angle of the ink duct roller, the angle being defined by the film nip and by the metering gap between the ink duct film and the ink duct roller, is of 70° to 110°.
In accordance with an additional feature of the invention, t according to claim 2, wherein a central angle of the film roller, the angle being defined by the film nip and by a printing nip between the film roller and an ink roller resting thereon, is of 70° to 110°.
In accordance with yet another feature of the invention, the ink metering system is supported on a bearing bushing of the ink duct roller via an adjusting device.
In accordance with yet a further feature of the invention, the adjusting device rests on a part of the bearing bushing protruding from a frame.
In accordance with yet an added feature of the invention, the adjusting device comprises a threaded pin and a lock nut.
In accordance with yet an additional feature of the invention, respective widths of the ink zones are determined by metering elements of the ink metering system.
In accordance with another aspect of the invention, there is provided a printing machine having an inking unit formed as a vibrator-less continuous-type inking unit, comprising an ink duct with an ink duct film inserted between an ink metering system, which is subdivided into ink zones, and an ink duct roller, the ink duct film within each of the ink zones in a region of a settable metering gap being held out of contact with the ink duct roller during printing.
In accordance with a concomitant aspect of the invention, there is provided a sheet-fed printing machine having an inking unit formed as a vibrator-less continuous-type inking unit, comprising an ink duct with an ink duct film inserted between an ink metering system, which is subdivided into ink zones, and an ink duct roller, the ink duct film within each of the ink zones in a region of a settable metering gap being held out of contact with the ink duct roller during printing.
The inking unit according to the invention, in a printing machine, requires that, during printing, the ink duct film inside of each of the ink zones in the region of a settable metering gap be kept out of contact with the ink duct roller.
A decisive advantage of the inking unit of the invention is that without sacrifices in terms of the metering stability, it allows the use of a simple, inexpensive ink duct film, which is no longer exposed at all to what in the prior art, namely, the published German Patent Document DE 199 14 179 A1, is merely reduced abrasion wear. The residual ink present in the ink duct after a printing job can to a great extent be removed from the ink duct along with the ink duct film. Thereafter, only very quickly performed fine cleaning of the ink duct and the insertion of a clean, new ink duct film into the ink duct are required before the ink to be used for
Roskosch Bernhard
Voge Michael
Funk Stephen R.
Ghatt Dave A.
Heidelberger Druckmaschinen AG
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