Study Of Key Technologies Of Selective Laser Sintering Processing Based On Temperature Field

Selective laser sintering (SLS) is one kind of rapid prototyping technologies, which sinters powdery material selectively to produce three-dimensional mechanical parts. During the manufacturing period of SLS, the preheating temperature of the powder and laser energy input are two important technologies. Because the preheating temperature field of the powder bed surface is not uniform, the mechanical property of parts sintered in different area is very different. So carrying on the study of the preheating temperature field at the powder bed surface possesses realistic instructional significance.The flux density on the powder bed surface from tilting and horizontal radiant panel is educed. A physical model for the steady-state preheating heat transfer of powder bed is established.Based on trials of the sintered density, the steady-state preheating temperature field at the powder bed surface is built. The temperature of powder bed surface can't be directly measured. But the sintered density of parts is merely depended on the preheating temperature while the other processing parameters are invariant. So according to the trial of different preheating temperature, an empirical formula of the sintered density and the preheating temperature is established; at the same time the sintered density trial of the same layer is carried out, and regularity of distribution of the sintered density of the same layer is detected. Combining with these two results the steady-state preheating temperature field of the powder bed surface is built.Based on the physical model for the steady-state preheating heat transfer, the steady-state preheating temperature field of the powder bed surface is analyzed by finite-element method. The temperature field of analysis is identical with the trial's result.Because the preheating temperature field at the powder bed surface is not uniform, in order to obtain nicer density of sintered parts, changing laser energy input under different preheating temperature is studied in theory, and an energy density formula for improving the sintered density is deduced. According to the trial an empirical formula of energy density adjusting for improving the sintered density is established. The empirical formula is used to sinter the strength parts in different areas, and the availability of the formula is verified.