Thermal drift in laser cutting of metallic mesh structures

向更高的产品复杂性的趋势需要扩大制造技术的理解，以应对研究和工业生产中的挑战。这种趋势在声音换能器等音频系统领域或电子能谱等表面分析领域中也有观察到。对于这封信来说，中心部件是一个网状卡洛特，它被用作电子光学透镜来聚焦电子束。这些部件形成网格结构，通过激光加工和额外的深拉伸制造。网状结构由薄腹板组成，刚度低，传热能力有限。不合适的激光扫描策略会导致热积累，从而导致材料的热膨胀。这将导致腹板宽度的偏差，并使这种网状结构的质量恶化。因此，金属薄板的激光加工需要新的技术和方法来解决这些挑战。到目前为止，激光加工只涉及局部问题。结果表明，激光加工的表面完整性高度依赖于周围介质和激光的扫描速度，而材料中的加热取决于脉冲持续时间、影响和重复频率。在激光加工过程中，薄板的整体热漂移问题很少引起人们的注意。特别是在大型薄金属片上产生许多缺口和微结构时。从自己的初步研究可以得出，特别是全局激光扫描策略对热积累有显著的影响。到目前为止，还没有一种方法可以描述与激光扫描策略相关的网格结构中的热漂移，从而能够利用这种行为。假设合适的扫描策略导致金属板的低温度偏差，从而导致均匀的热漂移，从而产生更规则的卷材宽度和缺口。

The trend towards higher product complexity requires to broaden the understanding of manufacturing technologies to rise to challenges in research and industrial production. This trend is among others observed in the field of audio systems like sound transducer or in the field of surface analysis like electron spectroscopy. For the letter, the central component is a mesh calotte, which is used as an electron-optical lens to focus electron beams. Such components are formed mesh structures, which are manufactured by laser machining and additional deep drawing. The mesh structures consist of thin webs, which show low stiffness and are limited in heat transfer. Unsuitable laser scan strategies lead to heat accumulation and consequently to thermal expansion of the material. This results in a deviation in web widths and deteriorates the quality of such mesh structures. Therefore, laser machining of thin metal sheets needs new techniques and methods to solve those challenges. So far, only local aspects in laser machining were addressed. It was shown for laser machining that e.g. surface integrity highly depends on ambient medium and scan speed of the laser, whereas heating in the material depends on pulse duration, fluence and repetition rate. Little notice has been given to the global thermal drift of thin metal sheets during laser machining. Particularly, when many notches and microstructures are produced on large thin metal sheets. It can be derived from the own preliminary studies that especially the global laser scan strategy has a significant effect on heat accumulation. So far, no methodology exists, which describes the thermal drift in mesh structures in dependence of the laser scan strategy to be able to take advantage of this behaviour. It is assumed that a suitable scan strategy leads to a low temperature deviation in the metal sheet, which results in an even thermal drift and accordingly to more regular web widths and notches.