Device for adjusting form rollers providing automatic compensation for change in packing thickness

摘要

A printing press having a plate cylinder and a cooperating cylinder, a layer of packing being interposed under the plate. A film of ink is applied to the plate by a plurality of form rollers. An eccentric bushing is interposed between the plate cylinder and the frame of the press rockable from a reference position to an adjusted position for increasing the spacing between the axes of the plate cylinder and its cooperating cylinder as necessary to accommodate an increase in the thickness of the packing. A cam sector is mounted at the end of the plate cylinder having spirally curved segments for radially supporting the rollers with respect to the plate and mounted for rocking movement for camming the rollers relatively away from the axis of the plate cylinder. The cam sector is rotatively coupled to the eccentric bushing for rocking movement in unison therewith and the spiral slope of each of the curved segments is such that the degree of rocking of the eccentric bushing necessary to accommodate a predetermined increase in packing thickness causes a total outward throw at each of the form rollers equal to the movement of the plate cylinder axis toward the form roller axis plus an amount equal to the added thickness of the packing, with the result that the spacial relationship between the form rollers and the plate is unaffected by a change in the thickness of the packing. In the preferred embodiment the cam sector is fixed to the eccentric bushing. Provision is made for individual adjustment of the radial position of each curved segment.