Mechanism And Experimental Study Of Laser Milling On Laser Cladding Parts

Problems about stick powder and rugged nodes usually appear on the surface of cladding layer in the laser cladding forming process. These problems can lead to the low accuracy of cladding layer. Laser milling technology is introduced in order to improve the quality of the layer. Increase and reduction of material are combined which make laser complex forming technique realized. In this paper laser milling technology towards laser cladding parts was studied and explored. The main contents are as follows:(1) According to the mechanism about interaction of laser and material, the mathematical model of surface roughness was established. The power density threshold of laser milling on cladding was calculated. Aimed at the defect of laser cladding layer uneven surface, the model that the flowing melt in the process of laser milling improve uneven surface was explored from a single point, then single channel of molten pool model.(2) Laser milling on laser cladding parts experiment was carried out. The crater dimensions influenced by mean power, laser pulse width, hatch distance, pulse frequency were investigated. The single channel milling roughness influenced by hatch distance was analyzed. Local roughness and overall smoothness influenced by mean power, laser pulse width and pulse frequency were researched. Back propagation artificial neural was established to forecast surface quality of laser milling cladding layer. The range analysis and variance analysis of orthogonal experiment was adopted to analyze the influence of laser process parameters. It turned out that hatch distance play the most important role markedly in local roughness, followed by the mean power. On the other hand, the mean power play the most important role markedly in local roughness followed by laser pulse width.(3) The thermal field of laser cladding layer under the irradiation of laser heat source was simulated based on finite element. The thermal field affected by different laser processing parameters was analyzed. The depth and width of simulation and actual measurement were compared. It turned out simulation is conformity with reality.(4) The microstructure of the Fe313 laser milling-cladding layer was analyzed. Laser milling can function as re-melting and hardening when the shaped surface is smooth. The grain was fine in the re-melting field. And the depth of refined field was deeper with the increase of laser mean power. But pulse width does not much affect the depth. Too high or low energy promote grain growth at the different levels. It was found by EDS that the elements of cladding layer changes regionally due to the effect of laser milling.Above studies show that using laser milling on cladding forming is high-efficiency and inexpensive. Compared with the existing laser cladding-mechanical compound forming, laser cladding-milling improve the work efficiency greatly, reduce the production cost.