基于离焦技术的光内送粉堆积变径体壁厚控制研究

分析了光内同轴送粉激光熔覆技术堆积变径回转体时壁厚"越堆越薄、薄厚不均"现象的成因,提出控制离焦量来逐层补偿熔池液态金属流失的方法,以保持熔覆层宽度不变。基于大量的实验数据得出离焦量变化量与变径回转体斜率之间的关系式,从而可在堆积过程中根据变径回转体斜率的变化实时控制离焦量的变化。通过实时控制离焦量,同时控制送粉量与激光功率,得到了表面质量较好、壁厚均匀的几个典型的变径回转体。成形件的金相组织细密,力学性能优良。对成形件进行了硬度测量,总体硬度相对基体较高且分布均匀。

Research on Thickness Control of Variable Diameter Solid with Coaxial Inside-Beam Powder Feeding Laser Cladding by Defocusing Technique

After analyzing the cause of the phenomenon of heaping thinner and uneven thickness in the wall thickness when coaxial inside-beam powder feeding laser cladding is used in the accumulation of variable diameter solid, we propose to control the amount of defocus layer by layer to compensate the pool of liquid metal loss and to keep the cladding layer width. Through a large number of experimental data, we demonstrate the relationship between the variation of defocus amount and slope of the variable diameter solid, and thus in the accumulation process the control of defocus amount can be changed in real time according to the variable rotary slope. By real-time controlling the amount of defocus, and correspondingly controlling the amount of the powder feeding and laser power, a few typical variable diameter rotating solid with good surface quality and uniform thickness are got. The molded parts show fine microstructure and excellent mechanical properties. The hardness of the molded parts is measured, the overall hardness is higher than that of the substrate and evenly distributed.