Study On The Coupling Of Laser Beam And Powder And High-level Accumulate Technology Based On Inside-laser Coaxial Powder Feeding

LCRM (Laser Cladding Rapid Manufacturing) is a combination of laser cladding technology and rapid prototyping technology, which combines the advantages of laser cladding and rapid prototyping technology and has become an important researching direction in the advanced manufacturing technology. At present, the way of powder feeding in this technology is the outside-laser coaxial powder feeding with many lateral powder tubes. This method has some shortcomings, laser beam and powder couple badly, the accumulated parts have rough surfaces, the heat efficiency is low, forming high-level high-precision parts are more difficult, the utilization of metal powder can only achieve 20% ~ 30%. In response to these deficiencies, this paper incomes a new optical coaxial powder forming process and mainly researchs the couple of laser beam and powder and the technology of high-level accumulation.The essential difference between inside-laser coaxial powder feeding and outnside-laser coaxial powder feeding is the change of the laser light path and the metal powder delivery .This paper analyzes the transformation and the coupling of laser beam and metal powder in the inside-laser coaxial powder feeding, compares with the outside-laser coaxial powder feeding.Analysis shows that inside-laser coaxial powder feeding has a lot of advantages,such as has adjustable beam energy distribution,can get the best state of the coupling of laser and powder;small powder beam is good at precision machining.During the process of vertical falling,the powder beam has a good heat-absorbing effect and high utilization of laser energy,the powder flying less , less pollution and greatly improved powder utilization.There is less no melt particle in the surface conducives to improving the surface quality.In laser cladding manufacturing process, the role of the energy flow, momentum and quality transportation is important, which exist in the metal powder under high-power laser and directly determine the size of the laser manufacturing parts, precision and performance. In this paper, calculates a model about the temperature rise in the coupling process of laser beam and powder, obtaines the temperature rise of the powder is relate to the powder's size and the time during traveling in the laser beam. according the specific parameters in the test, calculates the temperature rise of powder particle.Does high-level accumulation experiments of hollow cylindrical thin-walled parts and hollow cone-shaped thin-walled parts with the coaxial inside-laser powder feeding nozzle developed by the group. And takes advantage of height and temperature control,successes manufacturing a hollow cylinder whose height is 124mm,deep is 2.2 mm and surface roughness near 6.3 and a hollow taper whose height is 54mm,deep is 2.5 mm,tilt angle is 12.5°. Compares with the technics of many powder way coaxial outside-laser powder feeding ,the new type of powder feeding nozzle has obvious advantages, forms a high surface finish, the sides have no without melting particles ,ensure good dimension accuracy. Finally tests the forming pieces of the mechanical properties, hardness and so on ,the results of the analysis carried out to prove: Organize forming is dense defect-free , hardness is uniform, has a good tensile capability.