| Additive/Subtractive Hybrid Manufacturing(A/SHM)which integrates the advantage of both additive manufacturing and subtractive manufacturing is a rapid and sustainable way to directly obtain complex components with high precision and quality.Because of its various benefits,A/SHM is considered as a promising manufacturing process in the aerospace,mold fields.This study takes commercial maraging steel 18Ni300 powder as the research material and investigates the A/SHM process which combines of Selective Laser Melting(SLM)and Axial Ultrasonic Assisted Vibration Milling(AUAVM).The influence of laser power and scanning speed on the geometrical characteristic of SLMed single track is investigated.Actual overlapping ratio is measured and overlapping quality is evaluated at different parameters of laser power,scanning speed and hatch spacing.Balling effect of the scan track is further analyzed from the aspect of surface tension and the influence of laser power and scanning speed on Marangoni convection speed and molten condition of laser molten pool is also discussed by using finite volume method simulation.The single variable analysis is adopted to study the effects of laser power and scanning speed on SLMed workpiece quality in terms of mass density and hardness.Surface topography and internal morphology of SLMed workpieces are also observed.A laser power of 340 W and a scanning speed of 810mm/s are selected to build parts for the subtractive experiment considering energy utilization,surface topography and workpiece quality.Compared with other dry machining methods,AUAVM is selected as the subtractive method in A/SHM process.Through the kinematic analysis of end milling and finite element method simulation,it is concluded that the cutter and the part can separate from each other if the relationship of cutting speed,inclination angle,resonance frequency and amplitude satisfies a certain condition.Experiments are also conducted to prove the tool wear reduction.A decrease of surface roughness in AUAVM is also observed in the experiment. |
