US 5,511,480 AGranted

Method and apparatus for handling printed sheet material

AssigneeHoward W. DeMoore

InventorsHoward W. DeMoore, John A. Branson

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Abstract

A transfer cylinder for supporting freshly printed sheet material between printing units or at the delivery unit of a printing press is provided with an ink repellent, flexible jacket covering for supporting and transporting the sheet material without transfer of wet ink from one sheet to a successive sheet and without smearing the ink or causing indentations on the surface of the sheet material. The circumferential support surface of the transfer cylinder is covered with a conductive, fluoropolymer layer secured to the surface of the transfer cylinder beneath the protective, wash-free disposable flexible jacket covering. The low friction properties of the conductive base covering permit free movement of the ink repellent, flexible jacket covering relative to the transfer cylinder surface. Electrostatic charges delivered to the flexible jacket covering by the printed sheet material are drawn away from the flexible jacket covering and are discharged into the transfer cylinder by the conductive base covering.

Claims11

Dependent claims

A method for rotary offset printing in an offset press having multiple printing units, each printing unit employing a blanket cylinder and an impression cylinder for printing an printed image on one side of a sheet transferring between, comprising the following steps performed at each printing unit in succession:

transferring printing ink from the image area of the blanket cylinder to a sheet as the sheet is transferred through the nip between the impression cylinder and the blanket cylinder;
gripping and transferring the freshly printed sheet from the impression cylinder;
securing a base covering of low frictional coefficient material on the sheet support surface of a transfer cylinder, the low frictional coefficient base covering material having a frictional coefficient which is less than the frictional coefficient of the sheet support surface, and having radially projecting surface portions which reduce the surface area available for frictional engagement;
securing a flexible jacket covering over at least a part of the radially projecting surface portions of the base covering;
guiding the freshly printed sheet around the transfer cylinder as the freshly printed sheet is transferred from the impression cylinder;
and,
turning the transfer cylinder to engage the flexible jacket covering against the freshly printed side of each freshly printed sheet.

4 more elements

Dependencies are inferred from the claim text.