Micro Stamping Experiment Of Pure Copper Cup-shaped Parts And Numerical Simulation Study

In recent years,the demand for micro-parts in various industries is increasing.It has been widely used in aerospace,medical,electronic communications,and other fields because of its superior conductivity,thermal conductivity and plasticity.The rapid rise of micro electro mechanical system(MEMS)has also promoted the development of miniaturization of parts.With the development of miniaturization and lightweight,micro-forming has a very broad development prospects because of its high efficiency,low cost,short duration and low pollution.The effect of grain size effect on the mechanical properties of copper foil is studied through annealing process.The effects of grain size and stamping process on the deformation behavior of cup parts were studied by micro-stamping experiments and simulations.The diameter of 0.9mm cup was successfully stamped.The diameter of 0.9mm cup was successfully stamped at the same time.The grain size increases with the increasing of annealing temperature and the tensile strength of copper foil decreases.The fracture mechanism of copper foil is changed from mixed fracture mode to slip separation fracture mode.The cup was successfully stamped after annealing.The protrusion of the cup mouth decreases when the grain size increases from 10?m to 20?m.As the grain size increase,the pits on the surface increase.The maximum stamping force decreases from 37.7N to 32.6N when the grain size increases from 10?m to 35?m.When the grain size increases from 35?m to 68?m,The maximum stamping force increases from 32.6N to 33.4N,the second peak value increases gradually and the heterogeneity of thickness distribution increases when the grain size increases from 35?m to 68?m.As the grain size is from 10?m to 35?m microns and the stamping speed is increased from 0.1mm/s to 1mm/s,the surface quality of cup parts will be improved a little.Serious impact lines will appear when the stamping speed reaches 10mm/s.As the grain size increases to 68?m,the surface quality of cup parts will decrease with the increase of stamping speed.The simulation results show that when the grain size increases from 10?m to 68?m,the wrinkle height increases from 9.41 Px to 21.19 Px on the inner surface of cup shaped parts,the width of inhomogeneous deformation area of cup mouth is increased from 0.03 mm to 0.16 mm,the standard deviation of thickness distribution increased from 5.73 to 6.99,maximum stamping force decreased from 19.63 N to 14.17 N and the distribution of stress and strain is more inhomogeneity.The tensile stress on the outer fillet of the cup shaped part is reduced when the punch radius increases from 0.25 mm to 0.3mm.The stress on the side of the cup increases when the punch chamfer increases from 0.3mm to 0.35 mm contrarily.As the punch chamfer size increases,the maximum stamping force gradually decreases,and the peak of the punch pressure appears later.When the chamfer is 0.15 mm,the maximum stamping force is maximum and the self-locking phenomenon of flange part causes serious mesh distortion at the bottom of the part.As the chamfering of the die increases,the maximum punching pressure decreases,the equivalent strain of the cup mouth increases,and the tensile stress of the flange is reduced during the forming process.