The relative transversal vibrations of printing-press cylinders that are pressed against each other via an mastic blanket

In this paper we present the results of a computer-aided analytical investigation of the relative transversal vibrations of the cylinders in a web-offset double-sided printing press. An original method for carrying out the investigation, using a computer simulation, is presented. The printing press consists of the following cylinders that rotate during its operation and are pressed against each other via a thin (about 2 mm) elastic, rubberized cloth (called a blanket): two plate cylinders, with printing forms attached to them, and two blanket cylinders, with a paper tape moving between them for the printing. During the investigation, the deflections of the cylinders as well as the elasticity and damping of the blanket and the cylinders' bearing units were assessed. These vibrations caused changes in the pressure between the cylinders, thus reducing the quality of the prints. After investigating the features of the free and forced relative vibrations of the cylinders, it was decided to reduce the intensity of the vibrations by using cylinders with identical dynamic responses. Data from the experimental investigation that show the impact of the variations of the pressure between the cylinders on the quality of the prints are presented. (C) 2004 Journal of Mechanical Engineering. All rights reserved.