拱形结构特别是其封闭合龙部分结构的成形研究, 在金属零件3D打印领域有着重要意义。采用激光光内送粉斜向堆积技术成形悬垂拱形结构; 提出熔池悬垂沉积法消除合龙部位产生的隆起与内凹缺陷; 分析斜面倾角、加载时间、加载功率等参数对熔池垂流度的影响规律, 并建立熔池悬垂偏移量理论模型。运用激光光内送粉熔覆斜向堆积技术和熔池悬垂沉积方法, 成功获得拱形封闭结构。测试结果表明：合龙部位由于变角度、变参数逐层充填, 成功消除了合龙顶端上凸、背面内凹缺陷, 合龙区最小壁厚为3.2 mm, 达到了设计尺寸要求。

The research on forming of arched structure, especially with closed feature, is of great significance in the field of 3D printing of metal parts. In this paper, an overhanging arched structure was formed by slant forming method with hollow laser beam inside power feeding. The overhang deposition method was proposed to eliminate the defects of the closed part that were the raised top and the recessed downside. The influence of slant angle, loading time, loading power and other parameters on the vertical fluidity of molten pool was analyzed, and the theoretical model of the vertical displacement of molten pool was established. The arched closed structure was successfully obtained by means of the technology of slant laser cladding forming with coaxial inside-beam powder feeding and the overhanging deposition method of molten pool. The test results show that the defects of the closed part that were the raised top and the recessed downside has been eliminated successfully by layered filling with variable angles and parameters and the minimum wall thickness of the closed part was 3.2mm that have met the requirements of design size.