Numerical Simulation And Experimental Research On Ball Spinning Of Magnesium Alloy Thin-walled Tube

Ball spinning is a continuous plastic forming process with small deformation area and low deformation force.Magnesium alloys have less sliding surface at room temperature and less plastic forming ability,but there is a great demand for deformed magnesium alloys in the market.In this thesis,AZ31 magnesium alloy is taken as the research object,through the numerical simulation and experimental research on the ball spinning of thin wall tube of magnesium alloy,the law and characteristics of the magnesium alloy spinning are explored.The specific research contents of this thesis are as follows:(1)The ball spinning process of AZ31 magnesium alloy thin-walled tube was simulated by ABAQUS finite element analysis software.In the single-pass spinning simulation,the changing law of the temperature field in the undeformed zone of the tube billet under different process parameters was analyzed.The stress-strain distribution of the tube billet after each pass of secondary spinning was analyzed in multi-pass secondary spinning simulation.(2)Based on the orthogonal test,the process parameters(spinning feed ratio,thinning amount,spinning Angle)were optimized,and the optimal parameter combination was found.The optimized combination of process parameters: the feed ratio is 0.1 mm/r,the thinning amount is 0.5 mm,and the spinning Angle is 24°.Under the conditions of spinning forming with this set of parameters,the maximum temperature value and the maximum displacement of the temperature band in the undeformed area of the tube billet are optimized.The maximum temperature in the undeformed zone can be stabilized at 71～80 ℃.The experiment of ball spinning was carried out and the results of experiment and simulation were compared.(3)With the increase of the number of spinning passes,the microstructure of AZ31 magnesium alloy thin-walled tube along the radial direction became more uniform and fine.The grains in the thin-walled tube of the first AZ31 magnesium alloy were mainly deformed grains,while the grains in the second and third thin-walled tubes were mainly dynamic recrystallized grains.After the fourth spin,the grains in the thin-walled tube were mainly subcrystalline grains and refined grains.(4)After the first ball spinning,the tensile strength and elongation of the thin-wall tube are 170.64 Mpa and 13.72 % respectively.After the second ball spinning,the tensile strength and elongation of the thin-wall tube are 182.83 MPa and 15.34 % respectively.After the third ball spinning,the tensile strength and elongation of the thin-wall tube were 193.12 Mpa and 16.83 % respectively.After the fourth ball spinning,the tensile strength of the thin-wall tube is 202.56 Mpa and the elongation is 18.10%.(5)The residual stress and roughness of the pipe were tested and the influence of process parameters on the residual stress and surface roughness was analyzed.