Study On Deformation Behavior Of Metal Foils During Micro Pneumatic Deep Drawing Process At Elevated Temperature

In recent years,with the rapid development of miniaturization of electromechanical systems,medical devices,and electronic communication devices,the demand for mcro-components has also increased rapidly,which promoting the rapid development of micro-plastic forming processes such as micro deep drawing process,micro blanking process,micro-bending process,and etc...It has become the first choice formanufacturing of the micro parts,which has a good development prospect,due to the advantage of high efficiency,high quality and low cost.Micro-deep drawing process is widely used in the field of micro-forming as a commonly used micro-plastic forming technology.The metallic micro-plastic deformation is belonged to the sub-millimeter in size.Due to the size effect,the theory of macro deep drawing process cannot be directly applied to the field of micro deep drawing process,which restricts the development of micro deep drawing process.The micro parts manufactured by the traditional micro deep drawing process generally have problems such as poor surface quality,severe edge wrinkles,low-yield,and large quantities springback.In order to solve these problems,the pressure medium is used to apply the forming pressure opposite to the drawing direction to the metal foil in the concave molding cavity in the micro deep drawing process at room temperature.The surface quality the edge wrinkles and the yield of the micro cup,were greatly improved.As well known,the formability of the metal foil can be improved during the micro deep drawing process at elevated temperature.In addtion,the load of punch during the forming process can be reduced.The high wall height of the microc cup can be obtained.However,the surface quality of the micro cup is poor.Therefore,to obtain the good formatibiltity of the metal foil and the micro cup with good surface quality during the micro deep drawing process,the mciro deep drawing process at high temperature with a pressure mediumis required.However,thetradational liquid medium is not suitable for high temperature forming porcess due to its ignition or vaporization temperature limitation.In this study,the micro pneumatic deep drawing process at elevated temperature was proposed.The effects of the deformation parameters such as the counter pressure and punch speed on the deformation behavior as well as the surface quality,wall thickness distribution and microstructure evolution of micro-cups of the metal foil during the micro pneumatic deep drawing process were studied.Are studiedin this work.The main conclusions were sumarized as follows:(1)In order to realize the micro pneumatic deep drawing experiment at elevated temperature and with counter pressure the schemes for upgrading the existing micro pneumatic deep drawing experimental equipment was proposed.(2)In order to study the influence of different process parameters of the micro pneumatic deep drawing prcess on the deformation behavior and microstructure evolution of the pure titanium foil,the micro pneumatic deep drawing prcesses with different counter pressure and punch speed was carried out experimentally.To study the deformation behavior and stress and strain state of the pure titanium foil during the micro pneumatic deep drawing prcesses at room temperature as well as elevated temperatures,the FEM simulations were carried out with different temperatures.(3)In order to obtain the influence of different deformation conditions on the deformation behavior of pure titanium foil,the FEM simulations with different deformation conditions such as the fillet radius of punch and die,temperatures,friction coefficients and counter pressures were carried out with the commericial code of LS-DYNA.(4)The infulences of the different counter pressures as well as punch speed on the wrinkle,thickness distribution,the evolution of microstructrue,stress and strain distibution,the thinning ratio of wall of the micro cup as well as the pnch load during the micro pneumatic deep drawing prcesse were analyzed by combining with the experimental results and FEM simulation results.