Thermal drift in laser cutting of metallic mesh structures

点击翻译按钮获取中文摘要

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.