Study On Rapid Manufacturing Process Of Metal Parts Based On Laser Cladding

Laser cladding forming technology combines laser cladding surface strengthening with rapid prototyping, with the characteristic of rapid heating and rapid solidification in the strong power. Laser cladding forming can give a new performance to metal parts and increasingly is the main developing direction in metal parts manufacturing. In the paper, rapid manufacturing process of metal parts based on laser cladding is studied in detail, the main content is showed as following:1. The energy transfer in the process of the interaction between laser beam with material, the phenomenal essence and main drive force of heat and mass transfer and the law of melt solidification, and the primary rule and influencing factors of crystalline nucleation-growth , is analyzed.2. Combining laser cladding theory and single-pass, multiple-pass, single-layer and multiple -layer cladding experiments, the formation reason of forming parts defects is studied. The effect of laser powder, spanning velocity, spot diameter, powder feeding speed and interface rate on macro-quality and micro-quality is researched. The results shows spot diameter is dominating influencing factor of cladding layer width, the height of cladding layer is decided by powder feeding speed and scanning velocity and dilution is controlled by adjusting power density. The fine cladding layer is received by optimizing processing parameters.3. Observing the appearance and microstructure, macro-crack and micro-crack is discovered. The mechanism of cladding layer crack is deeply analyzed, the mathematical model is established and the means of preventing crack is proposed. The microstructure and hardness distribution of cladding layer is investigated by scanning electron microscope and micro-hardness tester. The results show microstructure is fine and gradient distribution, the hardness of cladding layer is even distribution .The crystalline shape of cladding layer is controlled by the value of G/R. The prediction and control of micro-structure is simply discussed.4. By theoretical and experimental analyzing, laser power, spot diameter, scanning velocity and powder feeding speed have a important effect on the quality of cladding quality, the width and height of cladding layer is chosen as evaluation target of cladding layer quality. Based on artificial neural network and gene arithmetic, a non-liner model of the relationship of laser power, scanning velocity, spot diameter and power feeding speed with the width and height of cladding layer is established. The experimental and simulant results show that the combination of BP and GA, can effectively overcome the problems of BP neural networks, the maximal relative error absolute value respectively is 2.93% and 2.4%. Based on optimized artificial neural network, the precision control system is established and can apply in subsequent processing parameters optimization and the control of cladding layer quality on line.