METHOD FOR MODIFYING THE TOPOGRAPHY OF COATED SHEET METAL USING A LASER BEAM AND COATED SHEET METAL WITH A TOPOGRAPHICAL MODIFICATION OF THIS TYPE

摘要

In many cases, the coating material of coated sheet metal has a significantly lower boiling point than the sheet metal material. Thus an explosive evaporation of coating material can occur when sheet metal of this type is joined by welding, negatively affecting the quality of the connection. To improve the connection quality, narrow gaps are created by means of spacers, allowing the evaporating coating material to escape into said gaps. The spacers are created e.g. by the laser bombardment of the sheet metal. The aim of the invention is to reduce the deviations in distance between the sheet metal sheets by the appropriate shaping of the spacers. This is achieved by a method, in which the laser beam executes a displacement comprising transversal and longitudinal components through and/or around the centre of its processing surface. This creates a topographical modification with a spherical form, i.e. with an apex radius that is greater than the height of said topographical modification.