Vibration Analysis of Rotogravure Printing Press to Improve Print Quality

The influence of vibrations of the rotating bodies and of the entire rotary press on the print quality, particularly images, in a 4-colors rotogravure printing plant of magazines is here analyzed. The print quality is influenced by spatial synchrony with which the single-color image are printed, and is continuously controlled and monitored (register in technical terms) during the magazines production. Having ruled out a malfunction of the register control system, in presence of register errors that occur in special operating conditions and to explain the defective print, the vibrations that occur in the rotogravure printing plant have been analyzed. The analysis of the vibrations were of two categories: the first concerned the rotating bodies in direct contact with the paper web, the second covered the entire plant, i.e. the rotary press and its supporting structure. Through experimental tests and numerical simulations it results that the vibration of rotating bodies in direct contact with the paper web have negligible influence on the register errors, while the loss of quality of printed images can be explained by the vibrations of the structure as a whole.