A plurality of helical groove sections are provided on outer peripheral surfaces of press rollers provided in a curl elimination mechanism. Each of the groove sections assumes a shape extending in the circumferential direction of the respective press rollers; that is, a direction oblique to a transport direction of paper. Hence, when compared with a case where the groove sections are aligned in the transport direction of the paper, the paper is less susceptible to traces of the groove sections. Since the groove sections are provided on the press rollers, an attempt can be made to enhance dimensional accuracy of or reduce the weight of the press rollers.

An inking unit in a printing machine includes a screen roller and an ink metering system subdivided into inking zones and assigned to the screen roller for performing zonal ink metering on the screen roller, the ink metering system having metering elements disposed so as to be movable relative to one another.

A rotary printing press has at least one printing group with at least one waterless planographic printing forme. An inking unit is assigned to the printing group as is provided with a screen roller for use in conveying printing ink to the printing group. The screen roller has line engraving or cross-hatchings, with an angle of inclination or an angle of rise of between 50.degree. and 80.degree. and preferably also has a raster frequency of less than 80 lines or cross hatchings per centimeter on its surface area.