Offset printing unit

Details Offset printing unit Offset printing unit

1999-02-01

2002-06-25

Eickholt, Eugene (Department: 2854)

Printing

Planographic

Dampeners

C101S219000

Reexamination Certificate

active

06408747

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an offset printing unit having an impression cylinder and a cylinder pair including a form cylinder and a transfer cylinder for applying ink to a printing material web guided between the transfer cylinder and the impression cylinder.
2. Description of the Related Art
Offset printing units having a cylinder pair including a form cylinder and a transfer cylinder and whose transfer cylinder cooperates with an impression cylinder for applying ink to a printing material web guided between the transfer cylinder and the impression cylinder are generally known. In offset printing units used for newspaper printing, the form cylinder may be configured with one printed page in the circumferential direction and two printed pages in the longitudinal direction, or two printed pages in the circumferential direction and two printed pages in the longitudinal direction, or two printed pages in the circumferential direction and four printed pages in the longitudinal direction, depending on the configuration of the printing unit. In each of these configurations, the printed pages are arranged in portrait fashion in a broadsheet format.
SUMMARY OF THE INVENTION
It is the object of the invention to create an offset printing unit which permits the economic production of multifarious products with a relatively low technical outlay.
The following definitions apply to terms used throughout the specification and claims: “Broadsheet” refers to the size of one printed page of a newspaper format and “tabloid” refers to a printed page in a magazine format which is half as large as the “broadsheet” printed page. Furthermore, “broadsheet” pages are printed so that the pin holes (puncture holes) of the paper are arranged on the bottom of the page and “tabloid” printed pages have the pin holes arranged along a side of the page.
This object is achieved by an offset printing machine including a printing unit having an impression cylinder and at least one cylinder pair including a form cylinder and a transfer cylinder operatively arranged so that ink is applicable from the transfer cylinder to a printing material web guidable between the transfer cylinder and the impression cylinder. The form cylinder has an outer surface with a circumferential length and a longitudinal length configured such that each of a first, second, third and fourth print page array is independently fittable within the outer surface of the form cylinder. The first print page array is in a broadsheet format and includes one portrait printed page in the circumferential length and at least four portrait printed pages in the longitudinal length, the second print page array is in a book format and includes two landscape printed pages in the circumferential length and at least four landscape printed pages in the longitudinal length, the third print page array is in a book format and includes two portrait printed pages in the circumferential length and at least eight portrait printed pages in the longitudinal length, and the fourth printed page array is in the book format and comprises four landscape printed pages in the circumferential length and at least four landscape printed pages in the longitudinal length. The form cylinder further includes means for receiving a flexible printing plate in the circumferential direction and at least one flexible printing plate in the longitudinal direction. In addition, a circumference of the transfer cylinder is substantially equal to a circumference of the impression cylinder and an integral multiple of a circumference of the form cylinder.
The fact that the circumference of the transfer cylinder is larger than the form cylinder by an integral multiple permits the transfer cylinder to have a high degree of stiffness which also permits the form cylinder cooperating therewith to be effectively supported. The adjusting movement of the transfer cylinder to an impression throw-off position for an on the fly change of a printing plate is designed to be relatively large. It is possible for the bearing of the transfer cylinder, including its journals, to be of a large dimension which is particularly stable. On the other hand, the small diameter of the form cylinder creates a larger operating space between two double printing units, which can be encapsulated against noise more effectively with respect to the printing units. The larger operating space also increases the accessibility for mounting a device for automatically changing the printing forms and/or a device for washing the blanket.
In one embodiment, a plurality of blankets are arranged on the transfer cylinder in the longitudinal direction of the transfer cylinder. Slots or channels for fastening the ends of the blankets may be arranged offset with respect to one another in the circumferential direction of the transfer cylinder—preferably by 180° in the case of two blankets.
Given the use of the known possibilities of folding and cutting a printing material web in the longitudinal and transverse directions and of turning the printing material web or its partial webs after the printing material web has been printed, a double printing unit equipped according to the invention may be used to produce in an advantageously staged fashion in broadsheet format two printed pages, of variable products, arranged in portrait fashion on the form cylinder. This double printing unit has twice the capacity of printed pages with respect to a double printing unit having form cylinders which can be fitted in the circumferential direction with one printed page (once round), and in the longitudinal direction with two printed pages (single width). In the case, for example, of a product having eight printed pages in broadsheet format in a set, there is a need, depending on the desired coloring of the printed pages, for double the number of double printing units equipped with once-round and single-width form cylinders, and for an additional reel changer by comparison with the double printing unit according to the invention.
In a double printing unit equipped with doubly round (two printed pages in the circumferential direction) and single-width form cylinders, when full use is made of the page capacity production can be varied only in a stage of four printed pages, and the maximum printed page capacity can be used only in two sets. In contrast, production in the double printing unit according to the invention can be varied in one set in a stage of two printed pages in conjunction with maximum printed page capacity. On the other hand, the double printing unit according to the invention is also capable of implementing the other production possibilities of a double printing unit fitted with double-round and single-width form cylinders, that is to say double production (two products) with delivery via two folders and/or one product from two sets by one folder. On the basis of the capacity of eight printed pages in broadsheet format, a printing unit with double-round and single-width form cylinders is laid down with respect to the number of printed pages for the two forms of production, it being the case that for double production the same number of printed pages is always present in the two products, and for collect-run production the product comprises two sets with the same number of printed pages in the individual sets. In contrast, in the printing unit according to the invention variations are possible both in the number of printed pages in the two products for double production, and in the number of printed pages in the two sets of one product. Depending on the desired coloring, in the case, for example, of a product having eight printed pages in broadsheet format in one set, there is a need, by comparison with the double printing unit according to the invention, for twice the number of double printing units fitted with double-round and single-width form cylinders.
In the case of a double printing unit equipped with double-round and double-width (four printed pages in the longitudinal direction) form cyli

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