| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 88 === Coaxial laser cladding is proceeded by blowing metal powders through a coaxial nozzle. Since the powder stream is significantly affected by the boundary geometry in the processing, the gas velocity and the powder concentration are the major parameters for the process on an inclined substrate or cavity. Both the catchment efficiency and clad profile are determined by these parameters.
In this study, the effects of the powder stream on the inclined substrate are analyzed by theoretical and experimental approaches. A numerical approach by FLUENT software is used to simulate the plane cold powder stream on the inclined substrate, the powder concentration is calculated and compared with the experimental results by analyzing the scattering light intensity of the powder stream image. It could be seen that a modified Gaussian distribution of the powder concentration is projected on the inclined substrate. Finally a simplified function based on the Gaussian distribution is proposed to solve the clad profiles on the inclined substrates and cavity. In comparison with the real clad profiles, the difference is large at high inclined angle.
This work provides many information about the characteristics of the coaxial laser cladding on the inclined wall boundary, which is frequently met in the applications of laser welding and rapid prototyping. According to the analysis of the stream powder distribution, it can be summarized that the clad profiles could be accurately estimated only by the powder concentration of the cold stream on the wall boundary.
|
|---|
