Enhancement of understanding about electron beam deep welding processes by making use of real-time - Polarisation intensity quotient goniometry of the vapour capillary with a special view to functional connections of the weld pool dynamics

与激光焊接一样，电子束焊接也可能出现由熔池动力学引起的工艺不稳定性。为了增加EBW过程窗口，一方面需要更深入地了解蒸汽毛细管周围的流体动力学过程，另一方面也需要实时监测过程稳定性的测量方法。后者既可用于基础研究，也可用于实际应用中的质量监测。在这个项目的框架内，计划使用一种新的偏振角计，它可以确定观察表面的斜率，因此，特别是对毛细管几何形状的3D监测，具有非常高的时间分辨率。与电流测量的几何形状相关，因为它们在EBW中很常见，而且毛细管的自照明（x射线辐射）将有助于更好地解释这些电流测量。这将有助于增强熔池动力学的分析过程模型及其与定义的光束参数的相互依赖性，基于获得的关于蒸汽毛细管在三维空间上的时间变化的测量结果，特别是对于毛细管深度bbb50 mm。次要目标：在高扫描速率下定量测量毛细管几何形状。通过同步测量毛细管的x射线自照度，对计算的三维毛细管几何进行关联/校准。测定方法极限值的确定。几何极限之间的区别，如毛细管倾角和毛细管底部方向上的最大分辨率，以及金属蒸气等离子体随板厚增加而增加的自发光可能造成的测量限制。利用主要与温度无关的商图像的位置和角度信息以及p偏振和/或s偏振图像的强度分布，表示熔融表面的定性温度曲线。确定熔池的特定固有频率，以及根据主要焊接参数由局部熔波确定的叠加节拍。用光束振荡测量确定的激励对熔池振荡的影响。确定与理想圆梁不同的定义梁几何形状对熔池动力学的影响。

As in laser beam welding, process instabilities which are to be ascribed to the molten pool dynamics may also occur in electron beam welding. For the increase of the EBW process windows, a deeper understanding of the fluid-dynamic processes around the vapour capillary are required and, on the other hand, also measurement methods for the monitoring of the process-stability in real-time. The latter serves for fundamentals-oriented investigations and also for the quality monitoring in practical application. Within the framework of this project it is planned to use a novel polarisation goniometer which allows the determination of the slopes of observed surfaces and, thus, particularly the 3D monitoring of the capillary geometry with very high temporal resolution. The correlation with the geometry of current measurement, as they are common in EBW, and also the self-illumination of the capillary (X-ray radiation) shall contribute towards a better interpretation of these current measurements. This will serve for the enhancement of the analytical process model of the molten pool dynamics and its interdependence with defined beam parameters, based upon the gained measuring results about the temporal change of the vapour capillary in three spatial dimensions, particularly for capillary depths > 5 mm. Subordinate targets:Quantitative measurement of the capillary geometry at a high scanning rate.Correlation/Calibration of the calculated three-dimensional capillary geometry by synchronous measurement of the X-Ray self-illumination of the capillary. Determination of the limits of the measuring method. Differentiation between geometrical limits, such as the capillary inclination angle and the maximum resolution in the direction of the capillary bottom and also of a possible measurement restriction by the increasing self-illumation of the metal vapour plasma with increasing plate thickness. Representation of the qualitative temperature curve over the molten surface by using the position- and angle information of the mainly temperature-independent quotient image and the intensity distributions in the p- and/or s-polarised images. Determination of the specific natural frequency of the molten pool and also of superimposed beats by local molten waves dependent on the primary weld parameters. Measurement of the influence of a defined excitation of the molten pool oscillation by beam oscillation. Determination of the influence of defined beam geometries which vary from the ideal round beam, on the molten pool dynamics.