针对金属零件三维自由直接成形工艺中普遍存在的高能耗、高热残余应力等问题，提出了金属颗粒冷态高速微喷射增材制造新工艺。以常温下的高压氮气作为加速气流，利用微喷枪将微米级的金属粒子加速至其临界速度以上形成沉积。针对高速微喷射增材制造平台搭建、具有高加速性能与高分辨率的微喷枪设计展开了研究，并在此基础上，进行了单点成形与单线成形的试验研究，通过最小特征尺寸的大小与稳定度分析新工艺成形精度与成形质量，通过微观结构与显微硬度分析新工艺成形件的基本力学性能。试验结果表明：在一定范围内，通过喷射压力的变化可以实现单点成形尺寸的线性可控，通过喷射压力与导轨移动速度可以实现直线成形线宽与层厚的线性可控；试验中的0.9 mm的最窄线宽与低于8%的线宽波动量保证了该工艺一定的加工精度与成形质量；致密的微观组织结构与较高的显微硬度值保证了该工艺成形件良好的力学性能；多层扫描时层与层之间致密结合保证了该工艺逐层累加制造的能力。研究表明，金属颗粒冷态高速微喷射是一种稳定可控，可行的增材制造新工艺。
田小永
,
曹家赫
,
曹毅
,
田晓阳
,
张敏娟
,
李涤尘
. 金属颗粒冷态高速微喷射增材制造工艺研究[J]. 机械工程学报, 2016
, 52(3)
: 205
-212
.
DOI: 10.3901/JME.2016.03.205
High-speed metal particles cold-state impact based additive manufacturing is proposed to solve the problems which widely exist in metal parts free forming process, such as high energy consumption and high thermal residual stress. In the process, high pressure nitrogen (1.5~3.5 MPa) is used to accelerate metal particles and impact into the substrate forming the deposition at room temperature. High-speed impact platform and micronozzle which has both well acceleration performance and high spatial resolution are designed and made. Based on this, process research on accuracy of deposited points and lines are conducted by experiments. Experimental results show that the diameter and thickness of deposited points can be linearly controlled by process pressure while the width and layer thickness of deposited lines can be linearly controlled by process pressure and nozzle’s speed. Moreover, the minimum line width of 0.9 mm is achieved in the experiment to ensure the process sufficient accuracy while line width’s variation of 8% below is achieved to ensure the process sufficient stability. Furthermore, the dense microstructure and high hardness HV0.05 value are observed to ensure the parts good mechanical properties. Effective combination between layers is found to guarantee the ability of the process to manufacture parts layer by layer. Thus the process has been proved to be a stable, controllable and feasible additive manufacturing process.
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