Printing – Inkers – Roller
Reexamination Certificate
2001-08-09
2003-11-18
Hirshfeld, Andrew H. (Department: 2854)
Printing
Inkers
Roller
C101S351800
Reexamination Certificate
active
06647877
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to an inking unit, particularly for an offset printing machine, having a first smoothing roller, an ink feed unit formed as a droplet generator for applying a metered quantity of ink indirectly via an additional roller interposing the ink feed unit and the first smoothing roller, or directly, to the first smoothing roller, and a second smoothing roller operatively connected to the first smoothing roller for distributing the applied ink.
Inking units of the type mentioned at the introduction hereto have become known heretofore. It is disadvantageous that, with inking units of this type, a locally, relatively intensive accumulation of ink on a first smoothing roller is not completely evened out. In this regard, a locally limited and intensive accumulation of ink, which is also referred to as an “ink dot”, is produced by an application of ink to a smoothing roller, for example, by a valve technique already known heretofore. The published German Patent Document DE 43 27 212 A1 describes a transfer of ink in the printing unit of an offset printing machine by a digitally controllable ink jet printing apparatus, and the published German Patent Document DE 44 05 912 A1 is concerned with a contact-free application of ink to rotating printing systems. By the valve technique, it is possible to transfer an offset ink in a pulse-like manner in the form of small drops or droplets to a smoothing roller of an inking unit of an offset printing machine utilizing digital control. In this regard, what is involved is a virtually point-like application of ink to a smoothing roller, the extent of the ink application being considerably smaller than the nominal size of an inking area to be implemented or realized by the inking unit. It is disadvantageous that such locally limited, point-like accumulations of ink are visible on a printed paper sheet. The cause of such a qualitative restriction on the offset printing result is the aforementioned inadequate evening-out of the locally limited accumulation of ink (ink dot) by conventional offset inking units.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide an inking unit, particularly of an offset printing machine, which, in a relatively simple and reliable manner, achieves an evening-out of a locally limited accumulation of ink on a smoothing roller, especially of an offset inking unit, which is sufficient to improve the printing quality.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, an inking unit, comprising a first smoothing roller, an ink feed unit constructed as an ink droplet generator for applying a metered quantity of ink to the first smoothing roller, by one of an indirect and a direct path, respectively, the indirect path being via at least one additional roller interposing the ink feed unit and the first smoothing roller, and the direct path being directly to the first smoothing roller, and further comprising a second smoothing roller operatively connected to the first smoothing roller for distributing the application of ink, each of the first and the second smoothing rollers having a hard smoothing surface with a hardness of one of at least 80 Shore A and at least 30 Shore D, respectively, for forming a uniform film of ink.
In accordance with another feature of the invention, the respective smoothing surface is formed of a substance selected from the group thereof consisting of hard rubber, polyurethane and the composition known by the trade name Rilsan, respectively.
In accordance with a further feature of the invention, the ink feed unit is an inkjet device.
In accordance with an added feature of the invention, the second smoothing roller is operatively connected to a supporting roller.
In accordance with an additional feature of the invention, the smoothing surfaces have a hardness of 95 Shore A.
In accordance with yet another feature of the invention, the supporting roller has a supporting surface with a hardness of less than 60 Shore A.
In accordance with yet a further feature of the invention, the supporting roller has a supporting surface with a hardness of 25 Shore A.
In accordance with yet an added feature of the invention, at least one additional smoothing roller having a smoothing surface and disposed at a spaced distance from the second smoothing roller is in operative connection with the first smoothing roller.
In accordance with yet an additional feature of the invention, after the ink has been applied, the additional smoothing roller is disposed downline from the second smoothing roller, as viewed in the direction of rotation of the first smoothing roller.
In accordance with still another feature of the invention, the smoothing surface of the additional smoothing roller is a comparatively hard smoothing surface and has a hardness of one of at least 80 Shore A and at least 30 Shore D, respectively.
In accordance with still a further feature of the invention, the smoothing surface of the additional smoothing roller has a hardness of 95 Shore A.
In accordance with still an added feature of the invention, the smoothing surface of the additional smoothing roller is a comparatively soft smoothing surface and has a hardness of less than 60 Shore A.
In accordance with still an additional feature of the invention, the smoothing surface of the additional smoothing roller has a hardness of 25 Shore A.
In accordance with another aspect of the invention, there is provided an inking unit, comprising a first smoothing roller, an ink feed unit constructed as an ink droplet generator for applying a metered quantity of ink to the first smoothing roller, by one of an indirect and a direct path, respectively, the indirect path being via at least one additional roller interposing the ink feed unit and the first smoothing roller, and the direct path being directly to the first smoothing roller, and further comprising at least one additional smoothing roller operatively connected to the first smoothing roller for distributing the application of ink, the first smoothing roller having a hard smoothing surface with a hardness of one of at least 80 Shore A and at least 30 Shore D, respectively, and the at least one additional smoothing roller having a soft smoothing surface of less than 60 Shore A, for forming a uniform film of ink.
In accordance with a further aspect of the invention, there is provided an inking unit, comprising a first smoothing roller, an ink feed unit constructed as an ink droplet generator for applying a metered quantity of ink to the first smoothing roller, by one of an indirect and a direct path, respectively, the indirect path being via at least one additional roller interposing the ink feed unit and the first smoothing roller, and the direct path being directly to the first smoothing roller, and further comprising a second smoothing roller operatively connected to the first smoothing roller for distributing the application of ink, and a drive for rotationally driving the second smoothing roller at a circumferential speed differing from the circumferential speed of the first smoothing roller, for forming a uniform film of ink.
In accordance with an added aspect of the invention, there is provided an offset printing machine having an inking unit comprising a first smoothing roller, an ink feed unit constructed as an ink droplet generator for applying a metered quantity of ink to the first smoothing roller, by one of an indirect and a direct path, respectively, the indirect path being via at least one additional roller interposing the ink feed unit and the first smoothing roller, and the direct path being directly to the first smoothing roller, and further comprising a second smoothing roller operatively connected to the first smoothing roller for distributing the application of ink, each of the first and the second smoothing rollers having a hard smoothing surface with a hardness of one of at least 80 Shore A and at least 30 Shore D, respectively, for forming a
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Hinze Leo T.
Mayback Gregory L.
Stemer Werner H.
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