Investigating of the influence of non-stationary processes in arc plasma on the depth penetration in high frequency TIG welding

高频TIG （HF-TIG）焊接与传统TIG焊接相比的优点是电弧中能量密度的显著集中，或者更高的焊接深度或焊接速度。传统TIG弧焊与高频脉冲电流的潜在物理相互作用没有得到充分的研究：事实上，频率对深度焊接效果的影响被提及[EWM-2002]，但脉冲电流对熔深的影响没有得到研究。高频脉冲tig焊的焊接深度增加不是由焊接能量源功率的增加引起的，而是由物理机制（电弧收缩、电弧中电流密度的行为、焊池中的流体动力学等）的综合引起的，这些机制与高频脉冲电流与等离子体和金属（及其蒸发）的直接相互作用以及阳极工艺特性的变化有关。在开发自洽模型时应考虑到这一点。该项目的目的是开发一个自洽模型，该模型描述了hf - tig焊接中的物理现象，并提供了使用这些工艺增加焊接深度的机制的表征。这导致人们对高频tig焊接增加焊接深度的影响有了相当多的了解，这基本上是众所周知的，对有关复杂物理机制的影响依赖性的表达没有得到充分的描述。该项目提供了tig弧焊和叠加高频脉冲电流之间相互作用的基本见解。考虑到电弧、脉冲高频电流和金属基材三者之间的基本物理参数和相互作用机制的现有知识，将在耦合构件模型的基础上建立自一致模型。在此模型的基础上，确定了hf - tig焊提高焊接深度的机理，并对工艺参数进行了分析。此外，还考虑了脉冲形状、频率和电流等焊接参数对该机制的影响变量的评价和量化。为此，将采用理论和实验相结合的方法。所获得的知识尤其揭示了HF-TIG焊接的整体技术可能性和高频脉冲的使用来增加焊接深度的潜力。有了这项技术，高工件的优势将是有用的，同时更有效的热量输入和更好的能源利用，作为传统TIG焊接的替代方案。

The advantage of high frequency TIG (HF-TIG) welding in comparison to conventional TIG welding is a significant concentration of energy density in arc either a higher welding depth or welding velocity. The underlying physical interactions of a conventional TIG arc welding with high frequency pulse current are not investigated sufficiently: in fact, the effect of frequency on the depth welding effect was mentioned [EWM-2002] but the effect of pulse current on the depth of penetration was not investigated.Increase of the weldings depth by HF-TIG-welding is not caused by increasing the power of energy source of welding, but it is derived from the combination of physical mechanisms (Arc contraction, behaviour of the current density in arc, fluid dynamics in weld pool etc.) These mechanisms are associated with the direct interaction of HF-pulse currents with the plasma and the metal (as well as its evaporation) and with the changes of characteristics of Anode processes. This should be considered for development of self-consistent model.The aim of this project is the development of a self-consistent model, which describes the physical phenomena in HF-TIG-welding and provides the characterization of mechanisms to increase the depth of welding using these processes. This leads to a considerable knowledge of the effect of increasing welding depth by HF-TIG-welding which is basically well-known, the expression of the dependency of the effects on the concerning complex physical mechanisms are not described sufficiently. The project provides the essential insight of the interactions between a TIG-arc welding and a superimposed high frequency pulse current.The self-consistent model will be developed on the basis of coupled component models which consider the present knowledge about essential physical parameters and interactions mechanisms between the arc, the pulse high frequency current and the metallic base material respectively weld pool. Based on this model, the mechanisms for increasing the welding depth by HF-TIG-welding dependent on the technical parameters will be determined. Furthermore, evaluating and quantifying the influencing variables of this mechanism in interaction with the welding parameters such as pulse shape, frequency and current will be considered. For this purpose, theoretical and experimental methods will be used.The gained knowledge particularly discloses the potential of technology possibilities of HF-TIG welding in the whole and the usage of the high frequency-pulse to increase the welding depth. With that technology, the advantage of a high work piece will be useful with simultaneously more efficient heat input and better energy usage as an alternative for the conventional TIG welding.