Puls-zu-Puls-Wechselwirkungen beim Ultrakurzpuls-Laserabtrag mit hohen Repetitionsraten
Puls-zu-Puls-Wechselwirkungen beim Ultrakurzpuls-Laserabtrag mit hohen Repetitionsraten
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DOI：
10.18154/rwth-2017-08668
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
Johannes Finger;A. Ostendorf;Reinhart Poprapwe
中科院分区：
文献类型：
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作者：
Johannes Finger;A. Ostendorf;Reinhart Poprapwe
脉冲持续时间在10皮秒范围内的超短脉冲激光源的应用能够实现非常精确的材料加工，加工工件的热负荷可以忽略不计。虽然加工质量很好，但就烧蚀率而言，生产率相当低，这是在许多情况下抑制广泛工业应用的主要缺点。本论文的主题是通过使用几百瓦的平均功率，同时将脉冲重复频率提高到几兆赫，将USP激光烧蚀提升到更高的生产率。最初，确定和研究限制升级过程的影响。当使用高重复率时，这些限制效应一方面是热积累，另一方面是等离子体或粒子羽流的屏蔽。在本论文的理论模型，这是能够描述这两个影响的可实现的生产率的影响。高重复率的USP激光烧蚀的两个效果的高度相关性证实了实验结果。热积聚导致熔化和非常粗糙的表面的产生，这对于大多数应用来说是不能接受的。另一方面，屏蔽效应导致所实现的生产率降低高达50%。因此，当通过使用高重复率进行放大时，需要考虑这些影响。通过比较实验结果和发展的理论描述，热积累和屏蔽效应可以归因于基本的物理量。在开发的工艺理解的基础上，对于Inconel 718的处理，实现了烧蚀速率的显著增加到超过30 mm 3/min的值。除了应用快速扫描技术以使用高重复率的方法之外，还提出了一种新的方法。基于对热积累的具体利用，使用传统的高柔性振镜扫描仪可以在良好的表面质量下实现相当高的重复率。Inhaltsverzeichnis i
The application of ultrashort pulsed laser sources with pulse durations in the range of up to 10 picoseconds enables very precise materials processing with negligible thermal load for the processed work pieces. While the machining quality is excellent, the comparable small productivity in terms of ablation rate is the main shortcoming that inhibits a widespread industrial application in many cases. Subject of this dissertation is the upscaling of USP laser ablation to higher productivity by using average power of several hundred Watts while increasing the pulse repetition rates to several megahertz. Initially, the effects that are limiting the upscaling process are identified and investigated. When using high repetition rates, these limiting effects are heat accumulation on the one hand and shielding by plasma or particle plumes on the other hand. Within the presented dissertation a theoretical model is developed, which is capable of describing the impact of these two effects on the achievable productivity. The high relevance of the two effects for the USP laser ablation with high repetition rates is confirmed by experimental results. Heat accumulation is leading to the generation of melted and very rough surfaces, which cannot be accepted for most applications. On the other hand, shielding effects lead to a decrease of the achieved productivity of up to 50 %. Therefore, these effects need to be considered when doing an upscaling by using high repetition rates. By comparing experimental results and the developed theoretical description, heat accumulation and shielding effects can be attributed to underlying physical quantities. On the basis of the developed process understanding, a significant increase of the ablation rate to a value of more than 30 mm3/min is achieved for the processing of Inconel 718. In addition to the approach of applying fast scanning technology to use high repetition rates, a new approach is presented. Based on the specific utilization of heat accumulation, it is possible to achieve comparable high repetition rates at good surface quality using conventional, high flexible galvanometerscanners. Inhaltsverzeichnis i