封闭空腔回转薄壁件的激光熔覆成形

Laser cladding forming of closed hollow cavity rotary thin-wall parts

封闭空腔结构具有大倾角的特征，如采用传统的水平分层法堆积，大倾角部分的熔池易产生塌陷，使成形无法进行；采用变角度法向分层堆积大倾角封闭区域时，存在激光与已成形部分的干涉问题。文中基于中空激光光内送粉技术进行了空间堆积封闭半球壳体的研究。将封闭半球壳体划分为变角度法向成形区域和斜定向成形区域，前者采用变角度法向分层方法进行堆积，以消除阶梯效应；后者采用斜定向错位分层方法进行堆积，避免了封闭区堆积时激光与已成形部分的干涉。建立了斜定向分层堆积偏移模型，并通过斜墙试验验证了可行性，最终完成了封闭半球的熔覆成形。检测结果表明，成形件表面平整，尺寸误差在5%以内，壁厚稳定在2.7 mm左右，两种成形区域的显微组织整体均匀致密，硬度和强度总体保持稳定。

Many parts with closed cavity structure are widely used in many fields. This kind of structure has large incline angle, the molten pool will collapse and even the forming is unable to continue, when the way of horizontal slices is adopted. Especially, there is interference between parts deposited and the laser beam by the method of variable angle normal direction slices without adjacent layers. Based on hollow laser beam inside powder feeding technology, the closed hemisphere shell parts was researched. The closed hemisphere shell parts were divided into two parts including normal direction slices area and oblique orientation slices area. Normal direction slices method was used to eliminate staircase effect when depositing normal direction area and the oblique orientation dislocation slices method was adopted to avoid interference between parts deposited and the laser beam. The offset model of oblique orientation oblique orientation was established and the feasibility was verified by inclined wall depositing experiment. The cladding forming of the closed hemisphere shell was finished. Results show that the surface of the formed parts is smooth, the size error is within 5%, the thickness is stable around 2.7 mm, the microstructure of two forming area is compact, the distribution of hardness and tensile strength are stable.