Method and Apparatus for Processing a Sheet Before the Sheet Transport in the Grip of Grippers

Abstract

A method and an apparatus for improving the sheet transport in the grip of grippers in a sheet-processing machine, for example a printing press. The sheet corners of the print-free gripper edge are removed in order to increase the sheet stability and in order to avoid these limp sheet corners being able to turn over.

1 . A method for processing a sheet or sheet stack before transport in a grip of grippers through a sheet-processing machine, the method which comprises:
 removing sheet corners at a leading edge of the sheet provided for gripping the sheet.   
     
     
         2 . The method according to  claim 1 , which comprises removing the sheet corners only in a region of a print-free edge of the sheet. 
     
     
         3 . The method according to  claim 1 , which further comprises removing rear sheet corners at a trailing edge of the sheet provided to grip the sheet for sheet transport in a turning operation. 
     
     
         4 . The method according to  claim 1 , which comprises removing the sheet corners in a pre-stacking device or in a feeder of a sheet-processing machine. 
     
     
         5 . An apparatus for processing a sheet or sheet stack prior to transport in a grip of grippers through a sheet-processing machine, the apparatus comprising:
 a vertical guide;   a paper-milling device mounted on said vertical guide for up and down movement thereof;   said paper-milling device being disposed to remove sheet corners at a leading edge of the sheet provided for gripping the sheet.   
     
     
         6 . The apparatus according to  claim 5 , wherein said vertical guide is one of two guides assigned to a sheet leading edge and adjustably disposed for freely adjusting a format transversely with respect to a sheet transport direction. 
     
     
         7 . The apparatus according to  claim 6 , which further comprises guides assigned to a sheet trailing edge and adjustably disposed for freely adjusting a format transversely with respect to the sheet transport direction. 
     
     
         8 . The apparatus according to  claim 5 , wherein said milling devices each includes a cylindrical milling head, and said milling head is mounted such that an angle thereof can be adjusted in a horizontal plane. 
     
     
         9 . The apparatus according to  claim 8 , wherein said milling head is mounted to define an angle of a milling line less than 45°. 
     
     
         10 . The apparatus according to  claim 5 , wherein each milling device is assigned an extraction device for paper scraps and sheet corners. 
     
     
         11 . The apparatus according to  claim 5 , wherein the sheet-processing machine is a rotary press.