Investigation On Micro-bending Of Sheet Metal Laminates By Laser Shock Soft Punch In Warm Condition

Because of its excellent mechanical and functional properties,sheet metal laminates have been widely used in micro products,which has aroused the researchers' attention to the micro forming of sheet metal laminates.In this dissertation,a new process for microbending of sheet metal laminates by laser shock soft punch in warm condition is proposed.First,the micro bending warm forming law of sheet metal laminates is studied experimentally.Secondly,the failure modes of sheet metal laminates are studied experimentally.Finally,the thermos-mechanical process and performance of micro bending of sheet metal laminates is studied by the thermal coupling numerical simulation.The main contents and conclusions of this dissertation are as follows:First of all,the micro-bending experimental system by laser shock soft punch in warm was built.The effects of laser energy,forming temperature,and die size on forming depth,surface quality,forming accuracy,thickness thinning ratio,and hardness distribution were investigated.The study found that,with the increase of the die size,the forming depth,thickness thinning rate and micro-hardness of the workpiece show tendency to ascend;with the increase of laser energy,the thickness thinning rate and micro-hardness of the workpiece increase,while the forming depth,surface roughness and attaching capability of the workpiece increase first and then decrease;as the forming temperature increases,the forming depth and forming accuracy of the workpiece increase,the attaching capability and symmetry increase,and the surface roughness and thickness thinning ratio decrease.Secondly,the experimental study on the failure modes of micro-bending of sheet metal laminates was carried out.The effects of die size,laser energy and forming temperature on the oxidation,necking and fracture of the workpiece were studied.Scanning electron microscopy and x-ray microanalysis system were used to test the forming performance of the workpiece.The results show that,with the increase of laser energy,the friction between the workpiece and the die increases,the flow of the workpiece material decreases,and the necking of the workpiece occurs.As the forming temperature increases,the element diffusion occurs at the interface of sheet metal laminates,and the thickness of the interface layer increases with the temperature.The metal surface to oxidation,and the oxidation of copper layer is more serious.As the forming temperature increases,the workpiece breaks away and necking is relieved.Finally,the thermo-mechanical coupling of the micro-bending by laser shock soft punch in warm condition was constructed by using ANSYS/LS-DYNA.The micro-bending warm forming process of the workpieces was simulated.The effects of forming temperature,laser energy and die size on the forming law of workpiece were discussed.Firstly,the reliability of the simulation was verified,and it was found that the simulation results can verify the experimental results well in the displacement distribution;the four major stages of micro-bending forming of the workpiece were revealed;the forming depth,forming temperature,the distribution of equivalent stress and equivalent plastic strain of the workpiece were analyzed,in which the forming depth of the workpiece increases with the increase of the die size and forming temperature,the change law of equivalent stress and equivalent plastic strain is consistent with the four stages of the workpiece forming process.