Importance

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Abstract

A die cutting press for processing web material is disclosed which is operable to provide very precise alignment of a reciprocable die cutting unit with each succesive area of the web to be die cut. In operation, the web is incrementally advanced toward the work station of the press until the area next to be die cut is substantially but not exactly in the die cut position thereof. The web feed is then placed in a creep mode to advance the web until an optical sensor determines the presence of transverse alignment indicium on one side of the web. Mechanism is thereupon actuated to rotate the die unit as required to bring the die assembly into alignment with related indicium on the opposite side of the web while effecting shifting of the web longitudinally thereof in a direction of travel as necessary to maintain die registration with the first sensed web indicium. Structure then shifts the die unit laterally of the web at the work station as required to bring the die unit into precise registration with longitudinally extending indicium on one side of the web. Only then is a defined area of the web subjected to the die cut unit. A cushion of air is provided for supporting the die unit while it is being rotated, during longitudinal shifting thereof in the creep mode, and as lateral shifting is accomplished with respect to the web. Extremely accurate is thereby accomplished registration of the die unit with the plurality of indicia associated with each area of the web subjected to the die cutting operation. Sensing of the presence or absence of alignment indicia on the web is preferably carried out through the use of photooptical devices associated with light transmitting flexible glass fiber bundles that direct light to the web as well as the light reflected therefrom back to the sensor mechanism. A microprocessor receives inputs from phototransistors to control operation of the die alignment and web advancement mechanism.

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First Claim