Printing unit for a printing machine

Abstract

The invention relates to a printing unit (1) for a printing machine, having an image cylinder (2), an image generating device (3) for setting an image on the peripheral surface (4) of the image cylinder (2), and an image transfer cylinder (5) which transfers the image from the image cylinder (2) to a printing substrate (6), the image transfer cylinder (5) having a resilient cover (7) which exhibits a deformation (10, 10′) in the force transmission areas (8, 9), and a transport belt (11) that carries the printing substrates (6) and is supported by a back-pressure cylinder (12) driving the image transfer cylinder (5) and the latter driving the image cylinder (2), by friction. Such a printing unit is to be developed in such a way that a continuous image cylinder speed (v(Ü)) is achieved. This is achieved by the back-pressure cylinder (12) being mounted such that it can be displaced with respect to the image transfer cylinder (5) with a travel-dependent pressing force (F(S)) which is dimensioned such that the speed of the image cylinder (2) remains constant with respect to changes in the effective radius (r) for driving the image transfer cylinder (5).

Dependencies are inferred from the claim text.