多光束激光选区熔化技术可提高传统激光选区熔化的成形效率, 实现大幅面复杂零件的直接成形。由于不同光束扫描区域之间会通过一定方式实现幅面拼接, 而拼接区的熔凝方式与其他区域不同, 这会对零件的成形特性造成影响。针对激光选区熔化区域拼接, 设计了重熔拼接和交错拼接两类拼接方式, 研究了拼接方式对TC4钛合金成形特性的影响, 分析了其表面形貌尺寸误差以及内部拼接缺陷的产生机制。结果表明在交错拼接方式下, 相邻两层之间的拼接界面彼此错开, 在保证相邻激光分区有效熔合的同时, 可有效控制激光重复扫描过程中重熔的影响范围, 成形试样表面平整, 内部无明显缺陷; 采用该拼接方式可提升的多光束激光选区熔化成形零件的尺寸精度及冶金质量。

Multi-beam selective laser melting (SLM) has been adopted to enhance the production rate and to enable the production of parts with dimensions exceed the layout of traditional single-beam SLM apparatus. Several overlapping methods can be applied to connect different scanning zones to form a large scanning layout, in the meantime the forming qualities of the components are affected by the overlap methods due to different melting/solidification behaviors in the overlap zones. In this paper, two kinds of overlap methods were designed: direct overlap and interleave overlap, to study the effect of overlap methods on the forming qualities, both the forming precision of top surface and metallurgical defects in overlap zones were analyzed. The results show that the join interfaces in the interleave overlap samples are alternative with each other in different layers, thus the ill bonding defects can be suppressed and the remelting effect from the repeating laser scanning can be effectively controlled; interleave overlap method is better for the forming of dense components with high precision when compared with direct overlap method.