Method for Stitch-Welding a Front Flange Joint

摘要

The invention relates to a method by which stitch welds (5) can be produced on the front faces of metal sheets (preferably on flanges) by means of laser welding. In order to produce the stitch weld seam, the following steps are repeated cyclically: pre-heating the joining partners (1, 2) in an area in front of the stitch weld seam to be produced, producing a short stitch weld section (7) at a relatively low resulting welding speed, and producing a section without a weld seam, as a result of which in each case an intermediate space (9) is formed between neighbouring stitch weld sections (7). The ratio of the lengths (6, 8) of intermediate spaces (9) and stitch weld sections (7) is selected in such a way that a degassing is achieved to such an extent that a high quality of the stitch weld seam (5) is achieved. The method is particularly suitable for producing welded joints between galvanized, heat-treated steel sheets, as are often used in automobile manufacture/vehicle body construction.

主权项

1. A method for stitch-welding a front flange joint comprising at least two joining partners (1, 2), by laser welding by means of a laser beam, in which during the welding process a continuous advancing speed of the processing optics in the main direction of advance is defined by means of the welding device, comprising the following steps which are repeated cyclically during the production of the stitch weld seam,
pre-heating the joining partners (1, 2) in an area in front of the stitch weld seam to be produced, in that a beam influencing device, by means of which the laser beam can be moved independently of the advance of the welding device, temporarily superposes on the continuous advancing speed of the welding device in the main direction of advance, by moving the laser beam, a movement speed of the laser beam in the direction of the stitch weld seam to be produced; producing a short stitch weld section (7) at a reduced resulting welding speed, wherein the resulting welding speed is composed of the superposition of the continuous advancing speed of the welding device and the movement speed of the laser beam that is defined by the beam influencing device; travelling over a section in the main direction of advance without forming a weld seam, as a result of which in each case an intermediate space (9) is formed between neighbouring stitch weld sections (7), wherein stitch weld sections (7) having a length (6) of less than 30 mm and intermediate spaces (9) having a length of more than 1 mm between the stitch weld sections (7) are produced.