Study of the current path in gas metal arc welding for the generation of a dynamic phenomenological system model

气体金属电弧焊中弧长调节是许多焊接电源控制理念的重要组成部分，以调节稳定的焊接过程。到目前为止，电流-电压特性的估计和统计值被用作确定弧长的输入。这里，为了简单起见，通常假设一维电弧模型，其中主要是弧柱长度可以变化，而弧套区域，导线电极和接触管的变化被忽略。但是，特别是电弧护套区域必须预期对输入功率有相当大的贡献，并引起额外的电压波动。因此，对接触管通过导线、液滴、含护套的电弧直至工件的电流路径进行详细的实验研究是本研究项目的目标。这条路径的不同部分应通过具体的实验技术以及通过确定和使用潜在物理机制的不同时间尺度分别进行分析。特别是，通过电信号的时间序列和复杂阻抗的测量来研究整个路径，应该与电弧的光学和光谱研究以及液滴库的探头测量相结合。作为描述子系统的动态和相互依赖行为的基础研究的结果，将以过程模型的形式描述当前路径。在此，将提供与现有解决方案相比，在气体金属弧焊工艺中弧长控制有相当大改进的先决条件。此外，该结果可用于后续研究，以改进金属蒸发影响下熔化电极的电弧附着和护套区域的物理模型。

The regulation of the arc length in gas metal arc welding is an important part of control concepts in many welding power sources to adjust a stable welding process. Up to now, estimations and statistical values from the current-voltage characteristics are used as input for the arc length determination. Here, often for simplicity a one-dimensional arc model is assumed where mainly the arc column length can be vary whereas variations in the arc sheath regions, wire electrode and contact tube are neglected. However, in particular the arc sheath regions must be expected to contribute considerably to the power input and to cause additional voltage fluctuations. Therefore, the detailed experimental study of the current path from the contact tube over wire, droplet, arc including sheathes up to the work piece is aimed in the research project. The different parts of this path should be analysed separately by specific experimental techniques as well as by determining and using the different time scales of the underlying physical mechanisms. In particular, the study of the whole path by time series of electrical signals and measuring the complex impedance should be coupled with optical and spectroscopic investigations of the arc and probe measurements at the droplet depot. A description of the current path in form of a process model will be available as a result of the basic study which describes the dynamic and interdependent behaviour of the subsystems. Herewith the prerequisites for a considerable improvement of the arc length control in gas metal arc welding processes in contrast to existing solutions will be provided. In addition, the results can be used in following studies to improve the physical models of arc attachment and sheath regions at melted electrodes under the impact of metal evaporation.