The Influence Of Inside-Laser Coaxial Powder Feeding Technology Parameter On Forming Under The Action Of Annular Facula

Laser cladding rapid prototyping bases on laser cladding is an advanced manufacturing technology, which was developed from rapid prototyping(RP). At present, the widely used method of powder feeding is lateral powder feeding and coaxial powder feeding process. This paper aims at studying the laser cladding rapid prototyping parts by annular laser facula and inside-laser coaxial powder feeding device to optimize the laser processing parameters.This paper establishes the simplified mathematics model of laser and powder reciprocity in the inside-laser coaxial powder feeding process and deduces the calculation formula of laser effect efficiency. Through theoretically calculation, at the same coordinate, laser effect efficiency increases with powder feeding quantity rising and powder velocity decreasing. When powder feeding quantity being an invariable numerical value, laser effect efficiency increases with a powder granule's time increasing in laser, which corresponds to the former study. This paper also analyses the energy distribution of annulus laser facula, the annulus laser facula is much propitious to shaped than traditional circular or rectangular facula; discusses the key process parameters that needed in the thin wall shaped parts experiment, such as laser power density, beam of light mode and scanning speed etc.Through several monolayer line scanning cladding experiment, multilayer line scanning cladding experiment, lines overlapping scanning cladding experiment in the multimode laser, analyzed their microscopic structure,hardness of shaped metallic parts. To obtain the parts with high precision and the excellent quality, the influence of many processing parameters on sizes of cladding coatings, precision and surface quality has been analyzed in detailed. These parameters include: laser power, scanning speed and ratio of overlapped. The results show that for getting the parts with best quality by, the value of overlapping ratios should be greater than that of the spot sizes. And furthermore, the optimum matching of laser power, scanning speed powder delivery speed is necessary, it is impossible to produce the high-grade laser cladding rapid prototyping parts within 14 mm determinate defocusing.The experiment results shows that the coupled performance of laser and powder reciprocity is excellent, the surface of parts is smooth, heat action of annular facula laser is sufficient, compared with the former prototyping process. Ultimately,the article analyses microscopic structure and hardness of shaped metallic parts. The microscopic structure is dense and has no defects and the hardness of shaped metallic parts enhances greatly.