Laser Cladding Forming Of Screwy Thin-walled Part Based On Coaxial Inside-beam Powder Feeding

LCRM is an advanced manufacturing technology developed from the1990s, itcombines the advantages of the laser cladding and the rapid forming technique, and isused widely in the car, steel, aviation, aerospace, and electronics industry. At present, inthis technology, the powder feeding way of forming is lateral coaxial powder feedingoutside the laser beam, in this way, laser beam and powder couples badly, theaccumulated parts have rough surfaces, and the utilization of metal powder is low.Soochow university laser special processing lab put forward a new laser claddingmanufacturing process with coaxial inside-beam powder feeding, it can make the laserbeam and the powder couple well, and improve the utilization rate of powder, also canmake the cladding layer more flat. In this paper, the temperature field of laser claddingand the forming process of screwy thin-walled part will be researched.In order to cover the shortage of the present powder feeding nozzle, this paper hasdesigned a pressure relief powder feeding nozzle base on coaxial inside-beam powderfeeding laser head, powder feeding effect shows that powder bunch become moreslender and straight under the restriction of the protection gas, it can improve thepowder utilization and be useful for the thin-walled parts laser cladding forming.The saddle distribution of energy absorbed at scanning direction is researched.Through building the finite element model of coaxial inside-beam powder feeding lasercladding, molten pool temperature field of single laser cladding is got, it is like a comet,and the high temperature area is like a saddle. The conclusion that the combinationbetween cladding layer and substrate can be judged by observed the molten poolcross-sectional temperature distribution isoline, and it is test by single laser claddingexperiments. The nodes in the middle of molten pool undergo warming and coolingtwice when the ring laser scanning across them. The temperature difference between molten middle and edge isn’t big, and it reflects the superiority of inside-beam powderfeeding laser cladding.The effects of laser power, powder feeding rate, scanning speed, anddefocusingamount to single cladding layer surface, height, and width are studiedscientifically. Some conclusions are obtained, and these can be the references for usingthis technology forming thin-walled screwy part and the application of inside-beampowder feeding laser cladding forming.Base on the single laser cladding experiments, screwy thin-walled part inside-beampowder feeding laser cladding forming initial parameters and test plans are confirmed.The finite element model of laser cladding forming screwy thin-walled part isestablished. The evolution of temperature field and thermal cycle of the node are studiedduring the screwy thin-walled part forming process. In the emulation laser power ischanged real time, and it can keep the molten pool temperature steady. The screwythin-walled part is formed successfully through storey height control and laser powerchange real time. Performance analysis shows that formed part has smooth surface and ahigh rigidity, no powder paste outside the surface, the size is basically the same to thedesign value, the microstructure is small and density, metallurgical combination isformed between part and substrate.