Primary Study Of Lean Parts On Inside-Laser Coaxial Powder Feeding Device And Process Of Laser Cladding Rapid Prototyping

Side of many metal parts have the lean geometrical character .Aiming at the disadvantages of fabricate metal parts with lean side without any support in the process of laser cladding rapid prototyping ,this article puts forward a new process of Inside-Laser coaxial powder feeding to fabricate lean parts offset and without any support. Compared with the process of lateral powder feeding and coaxial powder feeding,this article conclude the advantages of fabricate lean parts using the process of inside-laser coaxial powder feeding.By experiments,comparing and analyzing , this article conclude that the process of inside-laser coaxial powder feeding overcomes the disadvantages of lateral powder feeding and coaxial powder feeding: realizing the integrative coaxial function of laser, powder and gas, forward and vertical powder feeding inside laser, being steady and easily controlled of powder flow and shielding gas, excellent coupled performance of laser and powder reciprocity, parts surface quality and dimension precision are improved greatly .It can make the shaping of fabricate lean parts offset and without any support feasible and improve the general quality of the lean parts.Establish powder temperature rise model under the action of ring light, determine the condition of the powder particles when reaching the molten pool through calculate the temperature rise condition and choose the process parameters of the formation of the lean part ,ensuring to get the favorable cladding quality.Using new inside-laser coaxial powder feeding nozzle to do several monolayer cladding experiments in the multimode laser, the relation between different process parameters and cladding coat quality is obtained. This article establishes the academic model of the lean angle, and find out the process parameters which will influence the lean angle. Based on the former experiment research, experiment of fabricating lean parts offset and without any support is accomplished. Experiment results show that angle of lean parts make direct ratio to value of offset and scan velocity and make inverse ratio to powder feeding velocity. The results accord with the conclusion of academic model. This article put forward a concept of offset rate and find out the result of lean limit and collapse. Study and analyzed the process character of shaping lean parts, including different roughness degree on the inner surface and outer surface of the lean parts, different width of lean parts and different thickness of the lean parts.Based on the experiment research, experiment of fabricating lean parts offset and without any support is accomplished. During the process, laser power is synchronously controlled and Z axis increment is also modified very time. The lean part have certain lean angle and height and its surface quality is good.By micro measurement and hardness analysis, the study found that the combination between Fe-based sample and base plate is full metallurgical bonding; The microstructure of single cladding layer is continuous and tight, no gas cavity and crack; the microstructure of the lean parts have typical rapid freezing structure characteristics. The hardness of single cladding layer is homogeneous; The hardness of the lean parts is decrease from the surface of the lean parts to the base plate.