About Measurement and Computation of Ink Transfer in Roller Inking Units of Printing Presses.

In the development of inking units, the designer even today is dependent on empirical values or on unsatisfactory methods of computation. For this reason, a theoretical model for the numerical computation of ink transfer in roller inking units has been developed. The inking units to be examined were analyzed by means of a digital simulation with specially developed computer programs. This method permits a variation of the inking unit geometry, of the ink transfer functions, of the printing and non-printing areas of the printing form and of other important parameter by changing the input data. The final product supplied by the computer is the relief of ink-layer thickness on the imprinted material, allowing an exact qualify evaluation of the analyzed inking unit. Parallel to these theoretical examinations. experiments were carried out with a model printing press with variable inking device. A photoelectric multiple measuring device permits inertialess measurement of the ink-layer thickness shapes of the steel distributor roller as well as on the unscreened printing form. The ink-layer thickness relief transferred to the paper may then be determined by difference formation from the ink layer thickness shapes on the form cylinder before and after the nip. With the help of a special plotting apparatus, the shape of the optical density and also the layer thickness relief may be determined from the imprinted samples. With the aid of some examples the good qualitative consistency of the computed values may be shown. The designer thus is in possession of exact computation methods for the development of inking units.