Direct laser engraving of metal sheet on metal carrier, for rotogravure printing, employs sheet made from surface-treated copper or brass alloy

摘要

The metal sheet used for intaglio engraving, is a copper alloy. It is alternatively a bronze, a hard bronze or a white bronze. A copper alloy with a tin content of 4% to 31%, 5% to 9% or 25% to 31% is used. In addition or alternatively to the tin content, a proportion of zinc may be used. A brass is used. Before or after engraving, the surface is refined or hardened. A copper alloy is applied to a main body using a coating process, e.g. electroplating. Alternatively the copper alloy is applied by vapor deposition. A physical vaporization method may be used. A surface layer is produced on a copper ground, by application of alloying components onto the copper alloy. The layer thickness of the copper alloy layer is 1 mu m to 2 mm, or 1 mu m to 400 mm. The main body holding the gravure form has a steel carrier or core. The form is a cylinder (12). The laser engraving tool is a fiber laser (13). It is a pulsed- or continuous source designed and adjusted for use with the copper alloy. It is preferably paramatized. Independent claims are included for the following: (A) a gravure printing form; (B) and the laser engraving equipment.