Research On Hot Incremental Forming And Numerical Simulation Of AZ31B Magnesium Alloy Sheet

The sheet metal dieless incremental forming can greatly shorten the development cycle of new products and lower costs and solve the problems such as the small quantities and multi-species of the difficult sheet metal parts. Magnesium alloys are widely used in avigation and spaceflight, automobile and electron fields and so on for their low density, high specific strength, specific rigidity and excellent electromagnetic shielding. So it is necessary to study and develop dieless the incremental forming of Magnesium alloys sheet, and there is theoretical significance and applied value for perfecting plastic processing technology.This article is mainly studied the experiments and numerical simulation of hot incremental forming of AZ31B magnesium alloy sheet on the basis of its room and high temperature mechanics properties.The results of tensile test showed that, in the temperature of 150℃～300℃, the hot tensile stress is reduced with the increase of tensile temperature, and the extending ratio is increased. When the temperature reaches 250℃, the extending ratio is nearly to 118% and its anisotropy is the least; with the temperature further increasing, the extending ratio is 211%; the rupture of magnesium alloy sheet is ductile rupture. With the temperature increasing,μof the magnesium alloy increases and E reduces, When the temperature from room temperature to 300℃, the reduction of E is more than 85% and the increase ofμis more than 45%.This article summarized the research and development of the digital incremental forming home and abroad, and the sheet incremental forming is simulated by using FEM software LS-DYNA. Some key factor such as forming temperature,tooling head,feed step,sheet thickness and forming angle have been discussed, and the results are deepened by the sheet metal incremental forming experiments.The simulation and experiment results showed that: magnesium alloy sheet can be formed by the single point incremental forming under heating, and the formed part with good surface quality, no defects such as scratches and cracks; the forming tool head radius r impacts the forming time and forming accuracy of the workpiece; the optimum forming temperature range is 200～250℃; tool head feed rate is 0.1～0.6mm; sheet forming limit angle is 57°～68°, with the increasing of temperature and sheet thickness increases; the sheet thickness variety of the deformation area follows the Cosine law t = t₀×cosα.