Study On The Technology Of Inside-Laser Coaxial Powder Feeding Cladding And Rapid Prototyping Process Of Laser

Laser cladding rapid prototyping combines advantages about technology of laser cladding and rapid prototyping, is the research direction of advanced manufacturing technology, but now the type of powder feeding is the lateral powder feeding or coaxial powder feeding outside the laser about this process, there are many disadvantages: such as lateral powder feeding shows itself as parabolic motion of powder, being easily interfered by many external factors, asymmetry of powder in any section, poor coupling of laser and powder reciprocity, coarseness of parts surface, inefficiency of laser and powder thermodynamics reciprocity, difficulty in prototyping high quality parts and only twenty to thirty percent powder catchments efficiency. Aiming at so many disadvantages, this article puts forward a new process of hollow focusing laser, powder tube being medial and inside-laser powder feeding. Combines the existing experiment condition, researches the technology of this new process according experiments.The article discusses the course about laser and alloy powder reciprocity, researches the alloy powder in the area of laser, and discusses its efficiency. Established the model about alloy powder efficiency, according to experiment, the efficiency of the powder increases with the increase of powder cladding speed, at a point, it will fall down. And the same disciplinarian appears with the increase of scanning speed. At last, the powder efficiency is tested about sixty-eight point three percent, higher than that in the process of lateral powder feeding or coaxial powder feeding outside the laser.The article also discusses the key process parameters that are needed in the cylindrical shaped and taper shaped parts experiment, such as laser power density, beam of light mode,powder delivered speed,scanning speed etc. The steel medicinal pinhead is chosen as powder feeding nozzle and nitrogen gas is adopted as the pneumatic drive to feeding powder. Through several monolayer line scanning cladding experiment and multilayer line scanning cladding experiment the multimode laser, the relation between different process parameters and cladding coat quality is obtained. Based on the experiment research, cylindrical shaped and taper shaped parts prototyping experiment is accomplished with the new inside-laser coaxial powder feeding process. In the experiment process, laser power is synchronously controlled by the molten pool temperature collected by infrared temperature measuring apparatus and z axis increment is also modified every time. Experiment results shows that The shaping process of inside-laser coaxial powder feeding overcomes the disadvantages of the former shaping process: realizing the integrative coaxial function of laser, powder and gas, forward and vertical powder feeding inside laser, the shaping process is stable and reliable, the functional and process property of new powder feeding nozzle is superior to the traditional powder feeding nozzle and parts surface quality and dimension precision are improved greatly, compared with the former prototyping process. At last, the article analyses microscopic structure,hardness of shaped metallic parts and remainder stress. The microscopic structure is dense,crystal is thin and has no defects and the hardness of shaped metallic parts enhances greatly.