Research On Reciprocating Scanning Technology Ofselective Laser Melting

Selective Laser Melting(SLM)is one of the most developed technology in Laser Rapid Prototyping(LRP)manufacturing.At present,the SLM technology mainly exists problems of balling,porosity and low efficiency etc.in the process of forming,which seriously restricts the wide application of SLM technology.In order to the processing technology,we build the experimental platform composed of a fiber laser system,scanning system,powder spreading system,three-dimensional motion platform and software technology etc.Especially,sending powder structure is designed and debugged to improve the stability of the equipment operation.By using this experimental platform,this paper compares the effects of single-direction and reciprocating scanning on the surface morphology and cross section morphology of laser melting.To evaluate the surface topography with high melting sample variance.The results showed that with the increase of scanning speed,reciprocating scanning can improve the weld pool morphology characteristics;By reciprocating scanning method,the results show that it can realize energy distribution of different spots on the weld shape control;Finally,compare with the narrow-band semiconductor cladding and reciprocating scanning ring facula cladding experiment.It is found that reciprocating scanning of the cladding layer morphology distribution more uniform.Based on the laser melting experiments,the influence of processing parameters on the forming quality of SLM was investigated.The results show that with the increasing of laser power,the single track of width increases,which is always decreased when the scanning speed increases.Based on single track scanning experiments,the laser power,scanning velocity,scanning width,layer thickness and overlap rate as variable single scanning lap forming,influence of various factors on the evaluation of SLM forming quality.The experimental results show that with the increase of laser power,the surface roughness increases;the surface roughness is first increased and then decrease along with the increase of scanning velocity;when the scanning width increases from 1 mm to 10 mm,the surface roughness and deposition height of layer increases gradually.With the layer thickness increasing from 0.1 mm to 0.5 mm,the surface roughness and the powder burning rate increase;with the overlapping rate increases,the process of surface roughness decreases first and then increases,the overlap rate is between 30%-40% have low surface roughness and form high surface quality.Selecting reciprocating scanning strategy,with optimized parameters as the laser power of 500 W,scanning speed of 1000 mm/s,scanning width of 2 mm,layer thickness of 0.2 mm and overlapping rate of 30 % forming multilayer entity parts,the results show that with the layers increases,surface roughness has cumulative effect and surface quality becomes worse;when layers are melting 15 layers,the real parts of internal pore become less and relative induce density up to 96.3%.