Influence of the metal vapour on the beam properties and the capillary during laser beam welding by investigations at ambient pressure and in vacuum

在深熔激光焊接中，焊接过程受到工艺气氛和环境压力的强烈影响。这在毛细管的形成和焊接深度方面尤其明显。蒸汽毛细管及其稳定性是深熔激光焊接过程中的关键因素，毛细管的形成对焊接过程中发生的过程以及所得焊缝具有显著影响。毛细管的形成取决于环境压力和入射强度分布，而这又受到光路中工艺辐射的影响。根据环境压力和工艺区中的氧气含量，产生的金属蒸汽部分冷凝并固化成不同尺寸的金属颗粒，或与可用的氧气发生反应形成金属氧化物。根据发射的大小和类型，会发生吸收、散射、热散焦和光束偏转机制的混合。到目前为止，还没有对所得到的光束轮廓和焊接过程、毛细管形成以及最终焊缝上的个体效应的影响进行量化。工艺排放和纯环境压力的影响也没有-因此，所提出的项目的目的是通过调整环境气氛和环境压力，通过有针对性地影响工艺排放，分离各个相互作用机制对激光束的影响，并量化它们对强度分布和激光束强度的影响。毛细现象的形成。为了实现这一目标，第一步是定量和定性地确定常规焊接条件下工艺排放物的成分以及受控气氛环境压力的降低对工艺排放物的影响。此外，将研究具有不同成分的工艺发射对光束特性的影响。为此，将与工作激光束同轴地传播通过过程发射的测试激光束的束测量与射线跟踪相结合，以便分离过程发射对束特性的影响因素。此外，纯粹的环境压力依赖的影响，对毛细管几何形状的形成进行了研究，以及光束的性质，受工艺排放的影响，对毛细管几何形状的形成的影响。最后，这应该允许分离和量化不同影响因素对光束、毛细管形成和焊接结果的影响。

In deep penetration laser welding, the welding process is strongly influenced by the process atmosphere and the ambient pressure. This is particularly evident in the formation of the capillary and the welding depth. The vapor capillary and its stability is a key element in the deep penetration laser welding process and the formation of the capillary has a significant influence on the occurring processes during the welding process as well as on the resulting weld seam. The formation of the capillary is determined by both the ambient pressure and the incident intensity distribution, which in turn is influenced by the process emissions in the beam path.Depending on the ambient pressure and oxygen content in the process zone, the generated metal vapour partly condensates and solidifies into metallic particles of different sizes or reacts with the available supply of oxygen to form metal oxides. Depending on the size and type of the emissions, a mixture of the mechanisms absorption, scattering, thermal defocusing and beam deflection occurs. A quantification of the influence of the individual effects on the resulting beam profile and the welding process, the capillary formation, and finally the weld seam has not been performed so far. Nor have the effects of process emissions and the purely ambient pressure-dependent effects on the capillary geometry been separated from each other.The aim of the proposed project is therefore to separate the influence of the individual interaction mechanisms on the laser beam by the targeted influencing of the process emissions by adjusting the ambient atmosphere and the ambient pressure and to quantify their effect on the intensity distribution and the capillary formation.To achieve this, the first step is to quantitatively and qualitatively determine the composition of the process emissions under regular welding conditions and the influence of the reduction of the ambient pressure of a controlled atmosphere on the process emissions. Furthermore, the effect of process emissions with different compositions on the beam properties will be investigated. For this purpose, beam measurements of a test laser beam, which propagates coaxially to the working laser beam through the process emissions, are combined with ray-tracing in order to separate the influencing factors of the process emissions on the beam properties. Furthermore, the purely ambient pressure-dependent effects on the formation of the capillary geometry are investigated, as well as the effects of the beam properties, influenced by the process emissions, on the formation of the capillary geometry. Finally, this should allow to separate and quantify the effects of the different influencing factors on the beam, the capillary formation and the welding result.