Heidelberger Druckmaschinen Ag

Heidelberg Harris, Inc.

Heidelberg Harns Inc.

Edward Ellis Urquhart

James Brian Vrotacoe

Glenn Alan Guaraldi

Warren Hess Jarrard

Charles Douglas Lyman

A printing apparatus comprising a plate cylinder; at least one ink transfer roller for transferring ink to the plate cylinder; and a smoother associated with at least one of the at least one ink transfer roller for smoothing the ink on the ink transfer roller. Also provided is a method of providing ink for a printing apparatus comprising the steps of providing ink to an ink transfer roller transferring the ink to a plate cylinder; and smoothing the ink on the ink transfer roller using a smoother.

Smooth ink printing apparatus and method

An apparatus and method which reduces solid mottling in an offset printing press. One or more form rolls having a hard elastomeric outer surface, in the range of approximately 50-100 Shore A durometer hardness, preferably approximately 60-90 Shore A durometer hardness, are used to transfer ink to the plate cylinder. The use of a form roll of this type ensures a smoother application of ink to the plate cylinder, which in turn ensures smoother ink application to the blanket cylinder and printed web. If more than one form roll is used, it is preferable that, at a minimum, the final form roll, i.e., the last form roll the plate cylinder contacts in the direction of rotation, be a hard elastomeric form roll. In another aspect of the present invention, the form rolls can be made of a convex shape along their axial length, such that the diameter of the form rolls at their axial center is larger than the diameter of the form rolls at their axial ends. This is done to ensure proper contact between the form rolls and the plate cylinder. The present invention also encompasses a method of printing which reduces solid mottling and consumes less ink than in the prior art for an equivalent optical density.

Apparatus and method for reducing mottling in printing presses

An ink metering device and method. Ink is fed at a pressure to an orifice. Pressure may be achieved by either an ink pump or a gravity feed. The size of the orifice may be varied according the conditions existing in the printing press. The pressure at which the ink is fed may also be varied. Ink exiting the orifice is fed onto the surface of an ink applicator roll. At a location downstream of the orifice, a control blade is positioned adjacent the outer surface of the ink applicator roll. The distance between the tip of the control blade and the outer surface of the ink applicator roll may be varied using a control blade positioning mechanism. The distance between the tip of the control blade and the outer surface of the ink applicator roll controls the smoothness and/or the thickness of an ink film which is created on the surface of the ink applicator roll. This film is transferred directly to the image or plate cylinder, which is in contact with the outer surface of the ink applicator roll. The area between the control blade, the outer surface of the ink applicator roll and the orifice creates a cavity which includes a meniscus of ink directly behind the control blade. The action of the control blade and the meniscus will ensure that the film of ink on the ink applicator roll is smooth, and therefore that the ink applied to the image or plate cylinder is also smooth.

Ink metering device and method of metering ink

The present invention is directed to an apparatus for mounting a printing plate on a printing unit cylinder, with the printing unit cylinder having an opening in a clamping area. A lock-up bar is slidably mounted in the opening of the printing unit cylinder, the lock-up bar having an element for retaining at least one edge of a printing plate. A tucking device substantially extends on the clamping area, the tucking device being provided with a protection element and with a plurality of tucking elements arranged over the clamping area and over the width of the printing unit cylinder.

Apparatus for mounting flexible plates in a printing unit

In a lithographic printing press for printing on material in sheet or web form, a plate cylinder has a printing form mounted thereon. A gapless blanket cylinder is engageable with the plate cylinder and a tubular, removable blanket having a continuous surface is mounted on the blanket cylinder. Mechanisms to expand a cylindrical sleeve are provided as well as mechanisms to reduce cylinder distortion during rotation.

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Northboro, MA, United States of America

Edward Ellis Urquhart