METHODS FOR CREASING AND CUTTING SHEET MATERIALS

摘要

A preprinted sheet (12) is caused to advance along a predetermined path passing through one or two creasing machines (30, 60) which in succession place two arrays of straight creases (17, 18) on the sheet, producing a grid of crease lines in two perpendicular directions. The crease lines are placed at predetermined distances with respect to reference points (16) located on the sheet, for example reference marks printed on one surface of the sheet. The reference points are detected by optical devices (50) operatively associated with corresponding orientation devices (40) which correctly orientate the sheets in transit towards the creasing machines. Finally a cutting machine (90) cuts the edges or other parts of the sheet (12) using reference points already used to form the crease lines. In this way the cuts are made with absolute accuracy with respect to the crease lines.