Influence of self-regulation-effect on forming quality of thin-walled parts with variable laser spot cladding

To improve the forming efficiency and quality of laser cladding formed unequal width parts, some corresponding experiments were designed. A variable laser spot method was put forward to fabricate single-track cladding layers with unequal width by inside-laser powder feeding process. The influencing rules of continuously and piece-wise changed laser defocusing distances on the forming quality of thin-walled parts were analyzed during the process of changing laser spots. The experimental results showed that there was a “self-healing” effect on the cladding layer morphology with laser defocusing distance from -3 mm to -5 mm and the surface forming quality of cladding layers was good, and that the forming quality was poor with the laser defocusing distance from 0 mm to -2 mm. The height of cladding layer firstly increased then decreased with the growth of laser defocusing distance in negative laser defocusing range, and there was a maximum value at -2.5 mm. Within the range of positive laser defocusing, the cladding layer height had the same changing trend as in negative laser defocusing range with the laser defocusing distance, and also had a peak value at 2.5 mm. To obtain continuous sizes of the cladding layers, a splicing method of “self-healing interval” was put forward for variable laser defocusing distances. Hence, the thin-walled parts were fabricated layer by layer with continuously changed width from 1 mm to 3 mm. This study may provide a guidance for the fabrication of thin-walled parts with variable width by laser cladding forming using inside-laser powder. © 2016, Editorial Office of Journal of Xi'an Jiaotong University. All right reserved.