Printing – Rolling contact machines – Rotary
Reexamination Certificate
2000-08-08
2001-09-25
Eickholt, Eugene (Department: 2854)
Printing
Rolling contact machines
Rotary
C101S232000, C101S177000
Reexamination Certificate
active
06293193
ABSTRACT:
FIELD OF INVENTION
The present invention relates to methods for printing sheets in a rotary printing press. Sheets are initially printed in one or several colors on a first side. These sheets are directed to an intermediate storage device within the press. They are then again passed through the press and their second sides are printed in one or several colors.
DESCRIPTION OF PRIOR ART
It is generally known to first print the front of a sheet in the course of a first passage of the sheet through the press. Thereafter, the stacks of sheets that have been printed on one side are left waiting for several hours for the purpose of absorption and drying of the ink. A second passage through the press then takes place to accomplish this printing of the back of the page. For this purpose, each stack must first be inverted outside of the press, either manually or by means of a stack turner. Furthermore, a fresh printing forme must be provided, if different backs are to be printed for all front pages.
With large prime and perfecting printing, two sheet-fed rotary printing presses are often employed in parallel-one for prime printing and one for perfecting printing.
If the number of front pages is half, or less than the maximum width of the maximum press size, a single printing forme per color is sufficient, wherein the prime pages are arranged on one press half and next to them the perfecting pages for simultaneous printing. In the case of this “work and turn” printing, or the so-called turning, sheets printed on one side with prime and perfecting sides arranged centered in respect to the running direction are being created in the first press passage. During the second passage of previously printed and now turned pages, and the same printing forme, prime and perfecting sides are offset from each other in such a way, that two identical half-size sheets, each printed on both sides, are created as soon as the entire sheet has been cut along the center in the running direction.
Also, presses with sheet-turning attachments are used. These have, for example, downstream of four printing towers which accomplish prime printing, a special sheet-turning attachment. This device inverts each individual sheet and then guides it, with the previously rear edge now in front, through four further printing towers for perfecting, so that 4/4-printing over the full sheet size is accomplished.
DE 196 44 950 A1 describes a method for prime and perfecting printing in a sheet-fed rotary printing press, wherein a stack is pivoted over 180°.
SUMMARY OF THE INVENTION
The object of the present invention is directed to providing a method for producing printed sheets in a sheet-fed rotary printing press.
The object is attained by the provision of a sheet-fed, rotary printing press through which each sheet passes twice. On its first passage, a first side of each sheet is printed in a single or in multiple colors. The printed sheet is held in an intermediate storage area and is then turned. The second side of the sheet is then printed in one or a plurality of colors. Preferably each side of the sheet is printed with a prime print subject and a perfecting print subject using two adjacent print areas.
The advantages which can be achieved by means of the present invention primarily reside in that sheet-fed printing presses are made possible which are particularly space- and cost-saving and which are very flexible. In accordance with the present invention, these presses can be used, with maximum sheet size and with one passage of each sheet through the press for prime printing, or with two automatic passages of each sheet through the press for prime and perfecting printing in double production, for example with half-sized sheets with a single printing forme per color, i.e. with computer-to-press illustration or, for full size prime and perfecting printing, with two automatic press passages with an interposed new illustration for the different perfecting formes per color.
For example, in accordance with the method of the present invention, a four-color sheet-fed offset press can fully automatically produce either four-color printing in DIN A2 (=four pages DIN A4) printed on one side or, with double production, four-color printing in DIN A3 (=2 pages DIN A4) printed on two sides with one printing forme per ink color, or four-color printing DIN A2 (=4 pages DIN A4) printed on two sides (with a fresh plate illustration prior to the second perfecting sheet passage).
In connection with another described embodiment of the printing press, the method can fully automatically create, for example, six-color one-page printing in DIN A3 (=two pages DIN A4) with one plate illustration per color, or in six-color double-sided printing in DIN A4 or, with a second plate illustration, six-color double-sided printing in DIN A3 (=two pages DIN A4).
For this, only five cylinders are required for the printing process—without a gripper change for six-color printing per side of sheet. In comparison, a conventional
6
+
6
serial color press requires twelve printing cylinders, twelve rubber blanket cylinders and twelve plate cylinders and, depending on the construction, eleven or thirty-three sheet transfer drums between the printing cylinders. This conventional press needs at least twenty-three, or even forty-five critical sheet transfers, as well as an enormous space requirement. The prime and perfecting printing method, as well as the prime printing method, in accordance with the present invention, can perform six-color printing with one gripper closure per page and without sheet transfer. Novel presses in accordance with this invention can also be used in an advantageous manner for small batches and for “print on demand” work.
The presses in accordance with the present invention allow multi-color prime and perfecting printing without a sheet-turning attachment prior to the perfecting printing systems within the arrangement of the printing systems.
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Eickholt Eugene
Jones Tullar & Cooper PC
Koenig & Bauer Aktiengesellschaft
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