Physical and Numerical Modelling of Laser Dieless Drawing Process of Tubes from Magnesium Alloy

摘要

This paper is devoted to the development of technological process of production of magnesium alloy tubes by laser dieless drawing process. The purpose of the paper is the development and verification of the FEM code for simulation of LDD process and the study of main regularities of this process for magnesium alloy tubes. The problems of forecasting the geometric dimensions of the tube and the possibility of the crack of the material were considered. The developed FEM code takes into account the three-dimensional deformation of the material, thermal processes, laser heating, the mechanical properties of the material and process parameters. Calibration of the model included the definition of the absorption coefficient, which determines the efficiency of laser heating. For this purpose the experimental analysis of the temperature distribution during the process was made. In laboratory conditions the experiment of laser dieless drawing of tube from AZ31 alloy was performed with the initial outside diameter of 5 mm and a wall thickness of 1 mm. In the experiment the tube surface was covered with a graphite paint to increase the absorption coefficient. The value of absorption coefficient was determined by the inverse analysis and was equal to 0.12. The calculated results were used for producing tube in laboratory. As a result, a good correspondence of geometrical dimensions of the final tube with the calculated values was achieved.