Printing – Multicolor – Rotary machines
Reexamination Certificate
1998-05-11
2001-10-30
Asher, Kimberly L. (Department: 2854)
Printing
Multicolor
Rotary machines
C101S232000, C101S246000, C118S046000, C118S224000, C118S249000
Reexamination Certificate
active
06308620
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a sheet-fed rotary printing press having at least one unit which includes an impression cylinder and an additional cylinder assigned to the impression cylinder, the impression cylinder and the additional cylinder being relatively adjustable a spaced distance from one another.
In multicolor sheet-fed rotary printing presses, downline from which a varnishing unit is disposed, the transported sheets are printed with ink only in the initial printing units during the printing operation. Downline printing and varnishing units, respectively, are in an idling mode wherein the rubber blanket cylinder and the varnish blanket cylinder, respectively, are disengaged from the printing cylinder. A small gap is formed therebetween, through which the previously printed sheets are transported. Because of the high press speed, the sheets lift away from the respective printing cylinder, so that the freshly applied ink comes into contact with the rubber blanket or varnish blanket and smears.
The published German Patent Document DE 43 18 777 C2 shows a printing unit of a sheet-fed rotary printing press, wherein devices for aiding or promoting sheet guidance are provided, in order to avoid, respectively, smearing of and damage to the freshly printed image. The provisions taken in the heretofore known devices, however, are not always effective because, for example, in a rear region of the sheet, contact of the sheet end with the rubber blanket or the varnish blanket cylinder occurs, nevertheless, when the printing is performed on stiff sheet material.
SUMMARY OF THE INVENTION
Departing from the aforementioned prior state of the art, it is an object of the invention of the instant application to provide a sheet-fed rotary printing press which enables smear-free sheet travel when the printing, varnishing or finishing units are shut down.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a sheet-fed rotary printing press having at least one unit including an impression cylinder and an additional cylinder assigned to the impression cylinder, the impression cylinder and the additional cylinder being relatively adjustable a spaced distance from one another, comprising a sheet guiding device disposed on the additional cylinder for keeping sheets of printing material, which have been transported by the impression cylinder past the additional cylinder, away from the additional cylinder, once the spaced distance between the impression cylinder and the additional cylinder has been set.
In accordance with another feature of the invention, the additional cylinder is stoppable, so that it will not rotate while the impression cylinder rotates.
In accordance with a further feature of the invention, the sheet-fed rotary printing press includes a clutch via which the additional cylinder is decouplable from a printing-press drive for driving the additional cylinder.
In accordance with an added feature of the invention, the additional cylinder is formed with a cylinder gap approximately alignable with the impression cylinder in a stopped condition of the additional cylinder, for setting the spaced distance between the additional cylinder and the impression cylinder.
In accordance with an additional feature of the invention, the sheet-fed rotary printing press includes a detent for fixing the additional cylinder relative to a printing-press frame, in a position of the additional cylinder wherein the cylinder gap formed therein is in alignment with the impression cylinder, and in a condition wherein the additional cylinder is decoupled from a printing-press drive for driving the additional cylinder.
In accordance with an alternative feature of the invention, the sheet-fed rotary printing press includes a blast air connection for fixing the additional cylinder relative to a printing-press frame, in a position of the additional cylinder wherein the cylinder gap formed therein is in alignment with the impression cylinder, and in a condition wherein the additional cylinder is decoupled from a printing-press drive for driving the additional cylinder.
In accordance with yet another feature of the invention, the sheet guiding device includes at least one sheet guiding element secured to the additional cylinder.
In accordance with yet a further feature of the invention, the sheet guiding element is formed as at least one guide tongue.
In accordance with an alternative feature of the invention, the sheet guiding element is formed as at least one small wheel.
In accordance with another alternative feature of the invention, the sheet guiding element is formed as at least one blast tube.
In accordance with yet a further feature of the invention, the blast tube is couplable to a blast air connection at an end face of the additional cylinder.
In accordance with yet an added feature of the invention, the additional cylinder is formed with a cylinder gap, and the sheet guiding element being received in the cylinder gap.
In accordance with yet an additional feature of the invention, at least one cylinder of the impression cylinder and the additional cylinder is constructed so as to be engageable with and disengageable from the other for setting the spaced distance between the impression cylinder and the additional cylinder.
In accordance with still another feature of the invention, the sheet-fed rotary printing press includes a cylinder liner on the additional cylinder, the cylinder liner being removable from the additional cylinder for setting the spaced distance between the impression cylinder and the additional cylinder.
In accordance with still a further feature of the invention, the impression cylinder and the additional cylinder, between which the spaced distance is set, are rotatable in common with one another, while the sheet guiding device acts upon the sheet to be printed.
In accordance with still an added feature of the invention, the sheet guiding device comprises blast air nozzles disposed on the circumferential surface of the additional cylinder.
In accordance with still an additional feature of the invention, the additional cylinder has a stationary cylinder core formed with a chamber chargeable with blast air, and an outer casing rotatable about the stationary cylinder core, the outer casing having blast air ducts leading to the blast air nozzles.
In accordance with another feature of the invention, the sheet-fed rotary printing press includes a rotary valve assigned to the additional cylinder and, upon rotation of the additional cylinder, intermittently subjecting the rotating blast air nozzles to blast air whenever the blast air nozzles are directed generally towards the impression cylinder.
In accordance with a further feature of the invention, the at least one unit is a printing unit, and the additional cylinder is a cylinder for printing on the sheet to be printed.
In accordance with an alternative feature of the invention, the at least one unit is a varnishing unit, and the additional cylinder is a cylinder for varnishing the sheet to be printed.
In accordance with another alternative feature of the invention, the at least one unit is a finishing unit, and the additional cylinder is a processing cylinder having a circumference occupied by tools for processing the sheet to be printed.
In accordance with a concomitant feature of the invention, the at least one unit is disposed downline from at least one printing unit of the sheet-fed rotary printing press, as viewed in a sheet transport direction therethrough.
Preferably, the sheet guiding device forces the sheet to be printed approximately in the direction of the impression cylinder.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a sheet-fed rotary printing press, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without d
Leib Rudolf
Stephan Gunter
Wadlinger Ralf
Asher Kimberly L.
Greenberg Laurence A.
Heidelberger Druckmaschinen
Lerner Herbert L.
Stemer Werner H.
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