Web-fed printing machine for recto-verso printing especially of banknotes

Claim 1

A web-fed printing machine for recto-verso offset printing, especially of banknotes, with two first and second impression cylinders (2, 3) which are arranged next to one another in the main stand (1) of the printing machine and between which a paper web (P) runs through, said paper web being of paper having one side and an opposed other side, each of these cylinders being assigned blanket cylinders (4, 6) and several plate cylinders (5, 7) which are themselves inked by inking units (9, 9'; 11, 11') installed on both sides of the printing machine in two removable inking-unit stands (8; 10), wherein the two said impression cylinders have hard seamless continuous circumferential surfaces and around which the paper web (P) partially loops first round the first impression cylinder (2) in one direction and then round the second impression cylinder (3) in the other direction, and wherein installed between the main stand (1) and each of the inking-unit stands (8, 10) arranged on each side of the main stand is an exchangeable machine stand (15, 16) which is independent of the inking unit stands and in which are installed all said plate cylinders (5, 7) assigned to one of the first and the second impression cylinders (2, 3) and said blanket cylinders (4, 6), which each interact with one of these plate cylinders and which serve as ink transfer cylinders and ink one of the sides of the paper, first one side of the paper then the other side of the paper being printed directly with the individual colors, wherein the distance between the two impression cylinders (2, 3) being adjustable as a function of the paper thickness and being only of an amount necessary for the passage of the paper web between the two impression cylinders, so that the transfer of the paper web (P) from the first impression cylinder (2) to the second impression cylinder (3) takes place directly, the pressing force between the two impression cylinders (2, 3) being approximately equal to that pressing force with which an impression cylinder (2, 3) and a blanket cylinder (4, 6) are pressed against one another to form a nip, wherein the exchangeable machine stands (15, 16) each have the same construction and the same size and each having adjustable bearings for adjustable position for the respective plate cylinders (5, 7) and blanket cylinders (4, 6) installed therein, and wherein additional plate cylinders and blanket cylinders of a different diameter are mountable therein as a result of an appropriate adjustment of these adjustable bearings, wherein at least the first impression cylinder (2) which is the first in the direction of run of the paper, being equipped with a drying device (14) with temperature regulation, the drying device (14) at the first impression cylinder (2) being arranged near that portion of the circumference of this first impression cylinder on which the freshly printed paper is located before its transfer to the second impression cylinder (3).