Study On The Molten Pool Temperature Field Of Laser Cladding Under Variable Duty Cycle In Internal Hollow Laser Coaxial Powder Feeding Technology

This paper used "hollow beam, central powder pipe, inside-beam powder feeding " design principle and self-developed inside-beam powder feeding forming process and device to study the molten pool temperature filed in variable duty cycle (ratio of inner and outer diameter ring of light) hollow laser inside-beam powder feeding.The coupling mechanism of the powder and the laser system in Inside-beam powder feeding and outside-beam powder feeding is analyzed a simple model for the utilization of metal powder was built. Experiments demonstrated that in Inside-beam coaxial powder feeding forming process, the powder flow was stable and easy to control, the coupling of laser powder was better. In the existing conditions, the effective utilization of metal powders tested was 2 to 3 times than traditional outside-beam powder feeding technology.Used ANSYS finite element analysis software for Inside-beam powder feeding rapid prototyping technology, the transient temperature field finite element model was established, Element Birth and Death technology was used to simulate the deposition process of the cladding layers. Simulation analysis and experimental results were compared: laser cladding temperature field simulated results in good agreement with the experimental results, which proved the feasibility of numerical simulation, provided theoretical support for the design of Inside-beam powder feeding laser cladding rapid prototyping process and its powder feeding system.Parametric design language APDL was used to achieve heat source movement the influence of latent heat enthalpy deal was used to simulate the temperature field of Fe313 alloy forming parts the cladding bath temperature filed according to time variation under ring light was analyzed the results showed that: as the heat accumulation effect, the temperature inside the molten pool increased according to the increment of time and the cladding layer height.Changed the duty cycle, compared to the temperature field contours can be drawn: the duty cycle K affected the pool's shape, location and distribution of energy density, thereby affected the quality of formed parts. The results showed that: when K was in[0.35, 0.6], the pool's shape was "saddle or crescent" shape pool location was a little deviation after the laser beam center and biased on both sides pool distribution of energy density became uniform according to the K increment.When P = 3000w, spot diameter was 4mm, scanning speed V = 5mm/s and K was chosen 0, 0.35, 0.6 in sequence, the results of single and multi-cladding experiments showed that: the pool morphology was in accordance with the numerical simulation of temperature field cloud when K was 0.35, the microstructure of cladding under ring of light was better, the metallurgical bonding effect of cladding layer and the substrate was better.The FEM simulation of molten pool temperature filed of laser cladding was in accordance with the results of cladding experiments. The Simulation study in this paper achieved remarkable accomplishments, it ensured the quality of laser cladding layer obtained thin wall forming part of high quality morphology and compact structure and provided optimized technical parameters.