Machine for laser beam melting using continuous and ultra short pulsed laser irradiation

使用连续和超短脉冲激光照射的激光束熔化机

• 批准号: 534960237
• 金额: --
• 依托单位: Friedrich-Alexander-Universität Erlangen-Nürnberg
• 依托单位国家: 德国
• 项目类别: Major Research Instrumentation
• 财政年份: 2023
• 资助国家: 德国
• 起止时间: 2022-12-31 至 无数据
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/534960237?language=en
• 关键词: Machine; laser; beam; melting; using

Laser beam melting from the powder bed (PBF-LB), of e.g. metals, is an additive manufacturing process that can be used to create high-resolution structures. By focusing a continuous wave (CW) laser, small beam diameters and thus high-resolution structures can be generated. However, PBF-LB is very limited for processing materials that are susceptible to cracking, such as glass, because the high thermal gradients caused by the process lead to stresses inside the material and thus promote the formation of cracks. A promising approach for crack-free processing of such materials lies in the use of ultra-short pulsed (UKP) lasers. Although material interaction with a UKP laser in PBF-LB processes inevitably leads to material removal, smaller heat-affected zones (HAZ) result: a large part of the introduced heat is dissipated directly in the removed material. Such a minimised HAZ can be shaped into a desired melt pool geometry by selecting a suitable pulse repetition rate of the UKP laser. Although the thermal gradients in the material are higher than with CW lasers, the thermally induced mechanical stresses are below the strength limit of the brittle material due to the significantly smaller HAZ. As a result, the UKP laser in principle enables crack-free additive manufacturing even for materials that are susceptible to cracking. In this project, a PBF-LB system (for metals, ceramics, and silicates) is therefore applied for, which is operated simultaneously with a CW laser and a UKP laser. The collinear guidance of both lasers via the same beam deflection unit makes it possible to superimpose both systems during the additive manufacturing process. The aim is to evaluate the potential of combining both laser beam sources for the PBF-LB using the machine applied for. By superimposing the CW laser with the UKP laser, various advantages can be realised for the PBF-LB. For example, the CW laser can be used as a preheating and postheating source, while the UKP laser only contributes the amount of heat required for melting. This means that hard-to-weld materials can be processed reliably even in higher part layers. At the same time, the UKP laser enables the control of the cooling rates in PBF-LB. If, on the other hand, the CW laser is used for melting the powder material, the UKP laser can be used for local evaporation of material from this melt. This allows the cooling conditions to be tailored by reducing the melt bath volume. In addition to the aspect of simultaneous use of both lasers, the system offers further advantages, as each part layer can be processed in an alternating process using only the UKP laser in the "cold ablation" regime. This opens up a wide range of previously unavailable options for adjusting the internal and external component properties.

从粉末床（PBF-LB）熔化的激光束，例如金属是一个添加剂制造过程，可用于创建高分辨率结构。通过聚焦连续波（CW）激光器，可以产生小型梁直径，从而产生高分辨率结构。但是，PBF-LB非常有限地用于处理易受裂纹（例如玻璃）的处理材料，因为该过程引起的高热梯度会导致材料内部的应力，从而促进裂纹的形成。无裂纹处理此类材料的一种有希望的方法在于使用超短脉冲（UKP）激光器。尽管在PBF-LB过程中与UKP激光器的材料相互作用不可避免地导致材料去除，但较小的热影响区域（HAZ）结果：引入的大量热量直接在去除的材料中直接消散。通过选择合适的UKP激光脉冲重复速率，可以将这种最小化的HAZ变成所需的熔体池几何形状。尽管材料中的热梯度高于CW激光器，但由于HAZ的较小较小，热诱导的机械应力低于脆性材料的强度极限。结果，UKP激光原则上可以实现无裂纹的添加剂制造，即使对于容易受到破解的材料也是如此。因此，在该项目中，应用PBF-LB系统（用于金属，陶瓷和硅酸盐），该系统与CW激光器和UKP激光同时操作。两种激光器通过相同的光束挠度单元的共线引导使得在增材制造过程中可以叠加两个系统。目的是评估使用应用的机器组合PBF-LB的两个激光束源的潜力。通过将CW激光与UKP激光叠加，可以实现PBF-LB的各种优势。例如，CW激光器可以用作预热和后代的来源，而UKP激光器仅贡献熔融所需的热量。这意味着即使在更高层中，也可以可靠地处理难以处理的材料。同时，UKP激光器可以控制PBF-LB的冷却速率。另一方面，如果使用CW激光熔化粉末材料，则可以将UKP激光用于从这种熔体中局部蒸发材料。这允许通过减少熔融浴体积来量身定制冷却条件。除了同时使用两种激光器的方面，系统还提供了进一步的优势，因为每个零件层都可以在“冷消融”机制中仅使用UKP激光器进行交替处理。这为调整内部和外部组件属性的多种以前不可用的选项打开了。