Method and device for releasing a sheet from a blanket cylinder of a printing machine

US5884561A · kind A · utility

Assignee

• Heidelberger Druckmaschinen AG · DE

Inventors

• Norbert Thunker · Weinheim, DE
• Axel Hauck · Karlsruhe, DE

Key dates

• Filing date: Apr 9, 1997
• Grant date: Mar 23, 1999
• Expiry date: Apr 9, 2017

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B41F21/104
• WIPO field: Textile and paper machines
• WIPO sector: Mechanical engineering

Abstract

A method of releasing a sheet from a blanket cylinder of a printing machine, wherein the sheet is guided by an impression cylinder and held by grippers thereof, includes moving, with respect to the impression cylinder, elements of the impression cylinder holding the sheet, in a direction relatively counter to the direction of rotation of the impression cylinder, so as to produce an enlarged pull-off angle after a leading edge of the sheet has passed a printing nip between the blanket and the impression cylinders; and a device for performing the foregoing method. The background to the invention is the knowledge that higher tensile forces on a sheet are disadvantageous, and the object was therefore set of making available a method and a device in which the tensile force is reduced. This is achieved by means of a method in which, in order to produce an enlarged pull-off angle (.gamma.) after the leading edge of the sheet (1) has passed the press nip (6), the elements (5,5',5",5"') of the impression cylinder (4) which hold the sheet (1) are moved in relation to the impression cylinder (4), relatively counter to its direction of rotation (15). Furthermore, the object is achieved by mean…