Method for engraving printing cylinders

1. A method for engraving printing cylinders in an electronic engraving machine, comprising the steps of:

engraving at least two engraving lanes that lie next to one another in an axial direction on a printing cylinder with a respectively allocated engraving element;

generating signal values that represent rated density values to be achieved for drive of the engraving elements;

with the engraving elements driven with the signal values engraving cups into the printing cylinder whose geometry values represent actual printing densities that have been achieved;

prescribing a standard calibration function that describes a relationship between the geometry values and the rated printing densities;

calibrating electrical properties of the engraving elements such that, given drive of the engraving elements with signal values belonging to characteristic rated printing densities, cups having geometry values prescribed by the standard calibration function are engraved; and

matching the printing densities in the individual engraving lanes by

engraving cups in the printing lanes with which the prescribed, characteristic rated printing densities are to be achieved,

identifying the actual printing densities achieved by measurement after the printing,

deriving a corrected lane calibration for the respective engraving lane from deviations between the rated printing densities and the actual printing densities, and

applying the allocated, corrected lane calibration in the engraving lanes.

2. The method according to claim 1 wherein the corrected lane calibration is generated by determining corrected geometry values for the rated printing densities in the standard calibration function.

3. The method according to claim 1 wherein the geometry values of a cup are at least one of transverse diagonals, longitudinal diagonals, cup area and cup volume.

4. The method according to claim 1 wherein the corrected lane calibration is generated in that corrected signal values are determined for the signal values.

5. The method according to claim 1 wherein improved corrected lane calibrations are determined anew when deviations between the rated printing densities and the actual printing densities exceed a tolerance limit.

6. The method according to claim 1 wherein improved, corrected lane calibrations are determined anew after a prescribed time interval after a prescribed number of engraved printing cylinders or after a prescribed frequency of use of the engraving element.

7. The method of claim 4 wherein improved, corrected lane calibrations are determined by extrapolation from a time variation of the determined, corrected geometry values or the corrected signal values.

8. The method according to claim 1 wherein the measurement of the actual printing densities and of the geometry values is implemented by automatic measurement devices.

9. The method according to claim 1 wherein said measurements and the derived corrected lane calibration as well as time dependencies are stored and administered in a central computer.

10. The method according to claim 1 wherein corrected lane calibrations are continuously automatically adapted to varying properties of the engraving elements and of the engraving lanes.

11. A method for engraving printing cylinders in an electronic engraving machine, comprising the steps of:

engraving at least two engraving lanes on a printing cylinder with a respectively allocated engraving element;

generating signal values that represent rated density values to be achieved for drive of the allocate engraving element;

with the engraving elements driven with the signal values engraving cups into the printing cylinder whose geometry values represent actual printing densities that have been achieved;

prescribing a standard calibration function that describes a relationship between the geometry values and the rated printing densities;

calibrating electrical properties of the engraving elements such that, given drive of the engraving elements with signal values belonging to characteristic rated printing densities, cups having geometry values prescribed by the standard calibration function are engraved; and

matching the printing densities in the individual engraving lanes by

engraving cups in the printing lanes with which the prescribed, characteristic rated printing densities are to be achieved,

identifying the actual printing densities achieved by measurement after the printing,

deriving a corrected lane calibration for the respective engraving lane from deviations between the rated printing densities and the actual printing densities, and

applying the respective corrected lane calibration in the engraving lanes.