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.

从例如金属的粉末床（PBF-LB）的激光束熔化是可用于创建高分辨率结构的增材制造工艺。通过聚焦连续波（CW）激光，可以产生小的光束直径，从而产生高分辨率的结构。然而，PBF-LB对于加工容易开裂的材料（如玻璃）非常有限，因为该工艺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。一个有前途的方法，这种材料的无裂纹加工在于使用超短脉冲（UKP）激光。虽然在PBF-LB工艺中与UKP激光器的材料相互作用不可避免地导致材料去除，但会产生较小的热影响区（HAZ）：大部分引入的热量直接消散在去除的材料中。通过选择UKP激光器的合适脉冲重复率，可以将这种最小化的HAZ成形为所需的熔池几何形状。虽然材料中的热梯度高于CW激光器，但由于热影响区明显较小，热致机械应力低于脆性材料的强度极限。因此，UKP激光器原则上可以实现无裂纹增材制造，即使是对容易开裂的材料也是如此。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激光器同时操作。通过相同的光束偏转单元对两个激光器进行共线引导，使得在增材制造过程中可以同时使用两个系统。目的是评估使用所申请的机器将两种激光束源结合用于PBF-LB的潜力。通过将CW激光器与UKP激光器叠加，可以实现PBF-LB的各种优点。例如，CW激光器可用作预热和后加热源，而UKP激光器仅提供熔化所需的热量。这意味着即使在较高的零件层中，也可以可靠地加工难以焊接的材料。同时，UKP激光器能够控制PBF-LB中的冷却速率。另一方面，如果CW激光器用于熔化粉末材料，则UKP激光器可用于从该熔体中局部蒸发材料。这允许通过减少熔池体积来定制冷却条件。除了同时使用两种激光器的方面之外，该系统还提供了进一步的优点，因为每个部件层可以在“冷烧蚀”机制中仅使用UKP激光器在交替过程中进行处理。这将为调整内部和外部零部件特性打开以前不可用的各种选项。