Printing unit of a web-fed rotary press
View Patent ↗A printing unit of a web-fed rotary press has a plurality of press units, each press unit having a form cylinder, a transfer cylinder, an inking unit and optionally a damping unit, and having at least one impression cylinder. Each form cylinder rolls on the respective transfer cylinder and each transfer cylinder rolling on an impression cylinder in a thrown-on position of the printing unit, in order to apply single-color printed images onto a printing material which is moved through between the transfer cylinders and the or each impression cylinder. Each form cylinder bears a plurality of printing images next to one another in the axial direction, by which corresponding single-color printed images are applied to the printing material. The printing images which are arranged next to one another in the axial direction of the respective form cylinder are offset with respect to one another in the circumferential direction in such a way that deviations in the circumferential register between the single-color printed images which are to be printed in different press units can be compensated for.
1. A printing unit of a web-fed rotary press, the printing unit comprising a plurality of press units and at least one impression cylinder, each said press unit comprising:
a forme cylinder bearing a plurality of printing images next to each other in an axial direction, each said printing image corresponding to a single color printed image applied to a printing material; and
a transfer cylinder rolling on the at least one impression cylinder in a thrown-on position of the printing unit in order to transfer ink from the printing images on a respective said forme cylinder to a printing material, thereby forming printed images;
wherein the forme cylinder and the transfer cylinder are subjected to a deflection during printing causing a deviation in a circumferential register between the printed images; and
wherein said printing images on at least one of said forme cylinders are offset circumferentially with respect to each other based at least in part on the deflection of the forme cylinder and the transfer cylinder during printing so that the deviations in the circumferential register between the single-color printed images applied by the respective press units are compensated for whereby the printed images are longitudinally aligned along the axial direction.
2. The printing unit of claim 1 wherein each said forme cylinder carries a plurality of printing plates arranged next to one another in an axial direction, each said printing plate carrying a respective said printing image.
3. The printing unit of claim 2 wherein the printing plates on each said forme cylinder occupy positions which are offset circumferentially with respect to each other.
4. The printing unit of claim 2 wherein printing plates on each said forme cylinder are circumferentially aligned, only the printing images thereon being circumferentially offset.
5. The printing unit of claim 1 wherein each said forme cylinder carries a printing sleeve, said printing images being arranged on said printing sleeve.
6. The printing unit of claim 1 wherein said printing unit is configured as a nine cylinder printing unit having four said press units and a single said impression cylinder.
7. The printing unit of claim 1 wherein said printing unit is configured as a ten cylinder printing unit having four said press units and two said impression cylinders.