A method for checking the maintenance of register of printing images to be printed on two opposite sides of a printing material, in which the first side of the printing material is printed in a rotary printing press by a first printing unit cylinder, and in which the second side of the printing material, which lies opposite to first cite, is printed in the printing press by a second printing unit cylinder which interacts with the first printing unit cylinder. A printed image is printed by the first printing unit cylinder under the second printing unit cylinder. Afterwards, the printing material is printed in contact with the two interacting printing unit cylinders with the printing image, which is printed under the second printing unit cylinder, being printed onto the same side of the printing material together with an identical or a different printing image which is to be printed by the second printing unit cylinder during continuous printing of the rotary printing press. The printed images, which are printed together onto the same side of the printing material, are subsequently checked, with regard to their maintenance of register.

An oscillating roller system for a beverage can decorator is driven back and forth by a cam follower. A cam body having a cam is mounted to a frame of the inker system. Three oscillating cam roller assemblies are positioned about the cam body. Rotation of the cam oscillates the cam followers for each one of the oscillating rollers. Bearings of the oscillating roller assemblies includes an inlet gallery and outlet gallery for a closed loop lubrication system. The rollers are water cooled.

The machine comprises: a plurality of printing units each of which has a printing cylinder movable so as to allow adjustment of the position of the image printed by that cylinder in two perpendicular adjustment directions relative to the web of printing material; first manually-operated adjustment means arranged to allow a user to adjust manually the position of each printing cylinder; image acquisition means arranged to acquire images of register marks printed by the printing units along one or both sides of the web of material; and display means arranged to show, on an enlarged scale, the images acquired by the image acquisition means, so as to allow the user to detect any misalignments between the register marks and to properly adjust the position of one or more printing cylinders to clear said misalignments. The image acquisition means comprise a plurality of cameras each of which is arranged to frame.

A method for correcting a measurement value of a reference mark on a material web is disclosed. A controller, a machine, a computer program and a computer program product can perform a correction of this type. To improve determination of the position of a reference mark on a material web, a machine in which the material web is moved in a conveying direction has at least one tool that functions in a non-positive locking manner, a second tool that functions in a non-positive locking manner and is located downstream of the first tool in the conveying direction, and a sensor that is located between the two tools. A measurement error in the sensor which arises as a result of an adjustment of the second tool is determined at least approximately at least via parameter values of the second tool. The measurement value is corrected by the measurement error.