Printing plate unloading apparatus and method

Abstract

A rotary web-offset printing press is disclosed. It includes a plate cylinder defining a plurality of individual printing plate positions thereon and apparatus for removing printing plates from said individual printing plate positions or, for locating printing plates in said individual printing plate positions. The apparatus includes a discrete vacuum circuit associated with each individual printing plate position so that a negative pressure is generated within a vacuum circuit associated with an individual printing plate position when that vacuum circuit is closed by the presence of a printing plate in that individual printing plate position, wherein the plate cylinder is configured so that closure of a vacuum circuit and generation of a negative pressure is prevented when no printing plate is present in an individual printing plate position on the plate cylinder, the press including means for detecting the generation of negative pressure in each vacuum circuit and for providing information relating to the outcome of that detection to an operator to enable the presence of a printing plate in each individual printing plate position to be determined.

Description

technical field [0001] The present invention relates to an apparatus for unloading printing plates from the plate cylinders of a rotary offset printing press, and also to an apparatus which can be used to assist in loading these printing plates onto the plate cylinders of a printing press. More specifically, the present invention relates to devices for semi-automatic loading and unloading of printing plates. The invention also relates to a device for checking whether the printing plate position on the plate cylinder is occupied by a printing plate and for informing an operator of the result of this check. Background technique [0002] A web offset printing press consists of many printing units. Each unit is designed to print on the continuous web as it passes through the printing unit. The printed rolls from each printing unit converge at the folding unit, which orients, folds, and cuts each roll to produce finished products such as newspapers or magazines. Each unit cont...

AI Technical Summary

Problems solved by technology

However, it should be understood that this work is labor intensive and time consuming, especially when a large number of plates need to be changed

It also means that the press cannot be run for extended periods of time and has a significant detrimental effect on the overall productivity of the press

In fact, due to the increased demand for print and the need to meet very tight time constraints, many press operators cannot afford to keep their presses closed long enough to complete manual plate changes

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