Process And Finite Element Simulation On Friction Heat Incremental Forming Of AZ31B Magnesium Alloy

The characteristics of magnesium alloys are low density,high strength,good shock absorption,and good heat dissipation.It is a promising alloy material.However,because magnesium alloy is a close-packed hexagonal crystal structure,it is difficult to process and form at room temperature,so it needs to be heated during forming.Incremental forming realizes the rapid,complex and flexible manufacturing of thin-walled metal sheets,which is suitable for small batch and personalized forming technology.Generally,the heating method of incremental forming of magnesium alloy is electric heating,oil bath heating,etc.This article adopts the method of tool rotation and sheet friction to generate heat to simplify processing equipment,improve processing efficiency,and improve the magnesium alloy formability.The main research contents and conclusions of this article are as follows:(1)The mechanical properties and stress-strain curves of AZ31B magnesium alloy sheet are obtained through high temperature tensile experiments.The experimental data can be analyzed to draw conclusions.The anisotropy of AZ31B magnesium alloy is obvious when the experimental temperature is 100??150? and it has no obvious anisotropy when the experimental temperature is 200?;The accuracy of the tensile data was verified by the finite element(FE)based on ABAUQS.It can be seen that the tensile sample is more likely to be broken when the forming temperature is higher,and the sample has a higher tensile strength when it is stretched along the rolling direction 0°(following the fiber direction);By analyzing the fracture morphology of the tensile sample,it can be known that the forming property of AZ31B magnesium alloy increases with increasing temperature when the forming temperature is between 100? and 200?.(2)The Hill yield criterion was selected for FE simulation of magnesium alloy incremental forming through high temperature tensile test data based on ABAQUS.The distribution of Mises stress and sheet thickness is summarized.The maximum Mises stress is distributed in the lower part of the forming frustum,and the sheet thickness of the forming part tends to be stable in the middle of forming;The frustum thinning rate is analyzed when the forming temperature is between 100? and 200?.The optimal forming temperature for AZ31B magnesium alloy progressive forming is between 100??150?;It performs finite element simulation when the forming temperature is 150?.The maximum Mises stress and the maximum thinning rate increase with increasing friction coefficient and axial feed,and decrease with increasing tool diameter.The maximum Mises stress increases with increasing forming angle,and the maximum reduction rate decreases with increasing forming angle.(3)Contour contours were generated using the CAM module for incremental forming based on UG.The impact of the tool on the sheet is effectively reduced to reduce the probability of cracking by reducing the spindle speed at the origin.(4)The incremental forming experiment of AZ31B magnesium alloy sheet is heated by frictional heat generation.It can be known from the experimental results that the surface quality of parts decreases with the increase of the axial feed,it decreases with increasing spindle speed and increases with increasing tool diameter and forming angle within the forming limit.The influence of feed rate and spindle speed on forming quality is negatively correlated.The maximum forming high temperature increases with increasing axial feed,spindle speed,forming angle,and it increases first and then decreases with tool diameter;The influence of the forming limit in descending order is:spindle speed,axial feed,tool diameter;The reason of low temperature cracking is that the heat conduction is not timely through observing the fracture morphology of the sheet,which results in low temperature outside the sheet and poor plasticity.The faster impact of the tool on the starting point position caused the first initiation of cracks on the outside in the early stages of forming.The stress concentration causes the crack to propagate gradually as the tool drops.