激光熔覆层端部形貌三维重构模型

A Model of Constructing the End of Single-Track Laser Cladding Layer

激光熔覆层端部形貌对于激光立体成形加工精度及稳定性具有重要影响。基于粉末累积原理,分析了激光熔覆层端部的形成过程。构建了描述激光熔覆层端部三维形貌的分析模型。实验制备了单道激光熔覆层,应用激光共聚焦显微镜观察了激光熔覆层始末端部的形貌特征,并测量了不同横/纵截面的轮廓。结果表明,激光熔覆层端部沿扫描方向由外向内宽度/高度逐渐增加,经过约半个熔池的距离后,宽度达到熔覆层宽度保持不变,初始/末尾熔池外的区域高度达到稳态保持不变,而内部区域继续增加,两区域形成交界线。越过初始/末尾熔池后,熔覆层横截面达到稳态。模型与实验结果在主要几何特征上相符的很好,表明粉末积累是决定熔覆层端部形貌的基本机制,所构模型为认识理解激光熔覆层端部形貌提供了基础。

The morphology of ends of single-track laser cladding layer has an important influence on the processing precision and stability in laser solid forming. Based on the principle of powder accumulation, the formation process of ends of single-track laser cladding layer is analyzed. An analytical model of constructing the ends is developed. Some single-track laser cladding layers are prepared. By laser scanning confocal microscope, the ends of single-track laser cladding layers are observed. And the profiles of a series of cross section along the scanning direction and longitudinal section are measured. The result indicates that the width/height of the ends increase inward along the scanning direction. Beyond the distance of the radius of molten pool, the width of the ends equal to the one of the cladding layer and keep stable. Moreover, the height of the zone out of the initial/tail molten pool reaches stable while the one in the initial/tail molten pool keeps increasing. Between those two zones, a boundary of broken line is formed. Beyond the distance of the length of molten pool, the cross section of laser cladding layer reaches stable. The constructed result shows good agreement with the experimental one in the main geometry characteristics, which indicates the powder accumulation is the primary mechanism in determining the morphology of ends of single-track laser cladding layer. The developed model provides a foundation to get insight into the morphology of ends of singletrack laser cladding layer.