A metal rapid prototyping process based on the plasma arc deposition was presented. Some key process problems of thin-wall parts building,such as impact of the cross-section shape on the part' s quality,end-shrinkage control,temperature control and mechanical properties were investigated. The research results showed that flat deposited track is favorable to ensure the building quality. The end-speed-down method was adopted to avoid the end-shrinkage of the thin-wall part. Reducing heat input combine with the water-cooled method can avoid the building defects effectively. The mechanical properties of thin-wall parts were tested,and the test results showed that the tensile strength and elongation of the parts were corresponding to the mechanical properties of the filling wire. The longitudinal tensile strength and elongation of the parts were better than the transverse data.%介绍一种基于等离子弧熔覆的直接金属快速成型工艺.研究了薄壁件成型时成型轨迹截面形状对成型质量的影响、尾缩控制、成型温度控制,以及力学性能等关键工艺问题.研究结果表明,扁平截面的成型轨迹有利于保证成型质量；采用末端减速法可以有效地避免薄壁件的尾缩现象；采用减小热输入与直接水冷相结合的成型方式,能够避免成型时液态金属的过度流淌等缺陷；薄壁件的抗拉强度和延伸率与填充金属丝相当,水平方向的性能优于垂直方向.
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