Daimler Chrysler Ag

Daimler Ag

Daniel Zauner

Wolfgang Becker

Klaus Goth

Claus-Dieter Reiniger

Mike Paelmer

Jens Bühler

Markus Beck

Tilman Froschmeier

Markus Knöller

Claus-Deiter Reiniger

Alfred Fuchs

Markus Knoeller

Mike Palmer

Dirk Lindenau

In many cases, the coating material of coated sheet metal has a significantly lower boiling point than the sheet metal material. Thus, an explosive vaporization 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 vaporized coating material to escape through said gaps. The spacers are created e.g. by the laser radiation of the sheet metal. The aim of the invention is to reduce the variations 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 movement comprising transverse and longitudinal components through and/or around the center 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.

Method for modifying the topography of coated sheet metal using a laser beam and coated sheet metal with a topographical modification of this type

With many coated sheets, in particular zinc-coated sheets as used in the automobile industry, the coating material has a much lower boiling point than the material of the sheet. On welding said sheets together the above leads to explosive evaporation of coating material which seriously affects the quality of the connection. In order to improve the quality of the connection it has already been disclosed that narrow gaps between the sheets can be produced by means of spacers, through which the coating material can escape. The spacers can be produced for example, by means of laser bombardment of the sheets. A disadvantage is the relatively long time necessary for machining, which causes large costs in particular for serial production. The aim of the invention is to reduce the time necessary for machining the sheets whilst at least maintaining, preferably improving the quality of the machining. Said aim is achieved, by means of a method, whereby the laser beam is deflected onto the surface by means of a scanner device. A scanner device is a particularly rapid and flexible beam-diverting device. The above permits a reduction in the machining time by a factor of 10 without reducing the quality of the machining.

Method for the laser machining of coated sheets

A laser weld seam with reduced end crater and a process for production thereof are provided. The seam end is provided at a location, which exhibits a excessive material relative to the surrounding surface or thereby, that the seam towards the seam end exhibits a counter-running direction change of its preferred direction, which is designed in such a manner, that as a consequence of the interaction between cooling forward and counter-running seam a backfill of the melt towards the seam end occurs.

Laser welding seam with reduced end-crater and process for production thereof

The application of anti-corrosion base coating by cataphoretic painting (KTL) is well known in manufacturing automobile body parts. However the cataphoretic paint can penetrate only incompletely or possibly not at all into the gap in the contact areas of the components joined to each other. This type of gap is conventionally scaled following cataphoretic painting, in order to ensure corrosion protection for the entire assembly. The present invention makes it possible to dispense with the sealing in the production of an assembly of joined conductive components and nevertheless to ensure a sufficient corrosion protection. By introducing topographic changes in the components projecting from their surface in the known contact areas and then joining these components, they are spaced apart by the projecting topographic changes in such a manner that during cataphoretic painting the paint wets the entire surface of the assembly.

Assembly comprised of joined conductive components having cataphoretic paint layer and process for manufacture thereof

During laser beam welding a so-called end crater forms at the end of the weld seam. The end crater is formed by the volume shrinkage of the solidifying melt after the laser beam reaches the seam end and is switched off or repositioned. The end crater acts as a geometric notch and decreases the mechanical characteristics, in particular the operational stability, of the weld seam so that holes or tears in the area of the end crater can occur. The task of the present invention is thus comprised of providing a process for reducing end crater formation. The task is solved in that towards the seam end the focus of the laser beam is distanced from the surface to be welded and/or a transverse movement of the beam occurs.

Process for laser beam welding with reduced formation of end craters

Growing community of inventors

Ballendorf, Germany

Daniel Zauner