Abstract: A method for welding at least two aluminum-containing components is provided. The components have an aluminum content of at least 75% by weight. The method includes subdividing an output laser beam into multiple partial beams directed onto the components, so that multiple laser spots are generated on a surface of the components, and traversing a welding contour on the surface of the components with the multiple laser spots. Laser spot centers of at least three laser spots of the multiple laser spots are arranged in a ring formation. The output laser beam is generated by a multifiber, so that each laser spot of the multiple laser spots on the surface of the components has a core portion and a ring portion, with a mean power density in the core portion being higher than a mean power density in the ring portion.

Abstract: A method for welding at least two aluminum-containing components is provided. Each component has a content of at least 75% by weight of aluminium. The method includes subdividing an output laser beam into multiple partial beams directed onto the components such that multiple laser spots are generated on a surface of the components, and traversing a welding contour on the surface of the components with the multiple laser spots. Laser spot centers of at least three laser spots of the multiple laser spots are arranged in a ring formation. The output laser beam is generated by a multifiber such that each laser spot of the multiple laser spots on the surface of the components has a core portion and a ring portion. The welding contour is at least partially traversed by pivoting a first mirror in a controlled manner by a scanner optical unit.

Abstract: A method for laser welding of a workpiece includes welding at a corner joint of two workpiece parts of the workpiece by a welding laser beam to create an aluminum connection between the two workpiece parts, and feeding an output laser beam into a first end of a multiclad fiber to generate the welding laser beam. The multiclad fiber comprises at least a core fiber and a ring fiber surrounding the core fiber. A first portion LK of a laser power output of the output laser beam is fed into the core fiber, and a second portion LR of the laser power output of the output laser beam is fed into the ring fiber. A second end of the multiclad fiber is reproduced on the workpiece. The method further includes welding the workpiece by deep welding.

Abstract: Methods for determining the quality of a weld of a workpiece welded by laser-beam welding, wherein at least a partial region of a molten pool and/or of a surrounding area of the molten pool is observed by means of a measuring system during the laser-beam welding and the quality of the weld of the welded workpiece is determined on the basis of the observation result. At least one characteristic value that correlates with molten pool oscillation of the molten pool is observed during the laser-beam welding and a measure of an amplitude of the molten pool oscillation and/or a measure of a frequency of the molten pool oscillation is determined from the observed time curve of the characteristic value. A probability and/or a frequency for the occurrence of hot cracks at the weld of the workpiece is inferred.

Abstract: A laser beam directed is moved relative to a workpiece to weld along a weld seam and form a weld pool in the area surrounding the laser beam. The weld pool has a characteristic oscillation frequency fco, and a laser power is modulated with a modulation frequency f and a modulation amplitude ?=1?Pmin/Pmax, where Pmin is minimal and Pmax is maximal laser power during a modulation period. For a normalized characteristic oscillation frequency ?co and a normalized modulation frequency ?, ??2.2*?co, with ?=f·df/?, where ? is the feed rate of the laser beam, and df is diameter of a beam focal spot. Also, ?co=f,cotest·df,cotest/vcotest, where fcotest is a measured characteristic oscillation frequency, df,cotest the diameter of the beam focal spot, and vcotest is the feed rate of laser beam, all during a test measurement without modulation of the laser power.

Abstract: A laser beam directed is moved relative to a workpiece to weld along a weld seam and form a weld pool in the area surrounding the laser beam. The weld pool has a characteristic oscillation frequency fco, and a laser power is modulated with a modulation frequency f and a modulation amplitude ?=1?Pmin/Pmax, where Pmin is minimal and Pmax is maximal laser power during a modulation period. For a normalized characteristic oscillation frequency ?co and a normalized modulation frequency ?, ??2.2*?co, with ?=f·df/?, where ? is the feed rate of the laser beam, and df is diameter of a beam focal spot. Also, ?co=f,cotest·df,cotest/vcotest, where fcotest is a measured characteristic oscillation frequency, df,cotest the diameter of the beam focal spot, and vcotest is the feed rate of laser beam, all during a test measurement without modulation of the laser power.

Abstract: Methods for determining the quality of a weld of a workpiece welded by laser-beam welding, wherein at least a partial region of a molten pool and/or of a surrounding area of the molten pool is observed by means of a measuring system during the laser-beam welding and the quality of the weld of the welded workpiece is determined on the basis of the observation result. At least one characteristic value that correlates with molten pool oscillation of the molten pool is observed during the laser-beam welding and a measure of an amplitude of the molten pool oscillation and/or a measure of a frequency of the molten pool oscillation is determined from the observed time curve of the characteristic value. A probability and/or a frequency for the occurrence of hot cracks at the weld of the workpiece is inferred.