直接金属快速成形制造技术综述

探讨了当前国际上直接金属快速成形工艺的研究开发情况，认为工艺中的材料沉积方式很大程度上决定了制件成形过程中热量的输入、传导以及耗散特点，而工艺中热作用的过程将对制件微观组织、力学性能以及精度产生至关重要的影响。基于此点提出以材料沉积方式对制件造成的热影响的差别将直接金属快速成形技术进行分类的方法，并依照该方法将目前的直接金属快速成形技术分为选区沉积、熔覆沉积和熔滴沉积三大类工艺。对这三类工艺的技术特点和主要应用方面进行了介绍，并简要探讨了各类工艺的发展方向。重点分析了目前在这三类工艺的研究中存在的主要技术难点以及目前采用的解决方法，认为改善零件微观组织、力学性能以及尺寸精度的根本途经是对沉积工艺中热量的输入和耗散进行更加合理的控制并尽量减小。

OVERVIEW OF DIRECT METAL RAPID PROTOTYPING AND MANUFACTURING TECHNOLOGIES

Present research in metal direct RP&M technologies all over the world is discussed. The viewpoint is presented that the strategy for material deposition to a large extent determines the process's characteristics in the aspect of heat input and dissipation, while heat input and dissipation have a crucial influence on the parts' microstructure, mechanical properties as well as accuracy. From this point of view, a new classification criterion for metal direct RP&M is put forward which essentially classifies the technologies according to the differences in heat influence on parts during the processes. Based on this criterion, these technologies are classified into three categories: selective deposition, cladding deposition and droplet deposition, whose technical characteristics, applications as well as developing trends are also discussed. Special emphasis is concentrated on the analysis of technical problems as well as tried solutions. The principal approach for fabricated parts to get finer micro-structure, better performance as well as higher dimensional resolution is considered to be a more accurate control of heat input and dissipation. What's more, heat input should be as little as possible.