Hell Gravure Systems Gmbh

Heidelberger Druckmaschinen Ag

Ernst-Rudolf Gottfried Weidlich

In a method for engraving printing cylinders in an electronic engraving machine, printing densities are matched in individual engraving lanes by engraving cups in the printing lanes with which the prescribed characteristic rated printing densities are to be achieved. The actual printing densities are identified by measurement after the printing. A corrected lane calibration is derived for the respective engraving lane from deviations between the rated printing densities and the actual printing densities. The allocated corrected lane calibration is applied in the engraving lanes.

Method for engraving printing cylinders

In a method for making and evaluating a sample engraving in an electronic engraving machine for engraving printing cylinders for rotogravure, during a sample engraving, trial cups are engraved for predetermined tone values by an engraving element. After the sample engraving, a video camera is positioned at a predetermined axial measuring position, and a video image of the trial cups is recorded. The deviations of position of a measuring point of a selected trial cup are determined from a reference point as position errors &#x394;x, &#x394;y. The position errors &#x394;x, &#x394;yare then corrected by axially displacing the video camera to a new measuring position and/or by rotating the printing cylinder. Afterwards, the geometric values of the trial cup are measured and are compared with the geometric values of the predetermined tone values. The engraving control signal for guiding the engraving element is calibrated according to the result of the comparison such that the engraved tone values correspond to the predetermined tone values.

Method for generating and evaluating a sample engraving

A method for determining dimensions of an engraved cell formed by an electronic engraving machine, is described. During a test engraving period, test cells are engraved with desired dimensions defining predefined desired tonal values. An engraving element controlled by an engraving control signal is used for engraving a sequence of cells into a rotating printing cylinder resulting in engraved cells. Actual dimensions of the engraved cells represent actual tonal values. A measuring apparatus constructed as a mobile cell measuring instrument is placed on the printing cylinder to be measured. The actual dimensions of the engraved cells are measured and the actual dimensions are compared with the desired dimensions to obtain setting values for calibrating the engraving control signal such that the actual tonal values correspond to the desired tonal values. The actual dimensions of the engraved cells are transmitted wirelessly to a measured value receiver for further processing.

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Kiel, Germany

Ernst-Rudolf Gottfried Weidlich