Research On Forming Process Of TA1 Pure Titanium Thin Sheet Tiny Cupshaped Parts By Flexible Die Drawing

With the development of miniaturization and integration of devices in various industries,the demand for micro-parts formed from thin metal sheets is growing rapidly.Compared with the macro forming,in the micro forming process,on the one hand,"size effect" occurs when the material size decreases to mesoscopic scale,on the other hand,due to the small feature size of the rigid mold used in the micro-forming process,the gap during mold processing coordination is very difficult,the production cost is high,and the cycle is long.Therefore,the use of flexible materials as forming tools in the sheet metal micro-forming process has powerful potential advantages.The main advantages include solving the difficulty of the rigid mold clearance fit,and the workpiece is in contact with the flexible surface during the processing,which can significantly improve the product quality.Despite these obvious advantages,the current application of flexible mold microforming technology is still very limited.One of the reasons is that the deformation and failure modes of sheet metal in microforming process are still under study and not fully understood.In addition,in the process of microforming,especially under the condition of using flexible tools,the influence of related process parameters is insufficient.Therefore,in order to further promote the development of this technology and improve the product quality of micro-formed parts,this paper studies the forming process of TA1 pure titanium sheet flexible die micro-drawing,and analyzes the influence of different process parameters on the forming quality of cup-shaped parts.Firstly,uniaxial tensile experiments were carried out on TA1 pure titanium sheets with different annealing temperatures at room temperature to study the effects of different grain sizes and rolling directions on the mechanical properties of the material,and provide materials for finite element analysis based on this data attributes,which defines the deformation behavior of the material during the deep drawing process of the flexible die.The results show that the flow stress decreases with the increase of grain size under the condition of the same geometrical size of the material,which has obvious size effect.The sampling direction of the tensile parts has a certain influence on the stress and strain of the material.The tensile strength and elongation of the sample in the RD direction are higher than those in the TD and 45° direction.The tensile strength of the sample in the TD and 45° direction is very close,and the elongation of the sample in the 45° direction is better than that in the TD direction.Secondly,through ABAQUS finite element analysis flexibleware,a numerical model of flexible die drawing of TA1 pure titanium sheet was established,the forming process and stress and strain characteristics of flexible die drawing were analyzed,and the influence of different simulation conditions on the forming quality of deep drawing parts was studied.The results showed that the punch radius,the parameters of the flexible rubber mold and the friction coefficient has a certain influence on the quality of the formed parts.Finally,a deep drawing experiment was carried out on the TA1 pure titanium sheet through a self-designed flexible die micro-drawing experimental die.The effects of different blank holder springs,flexible rubber molds,drawing rates,friction conditions and initial grain size on the forming depth,wall thickness distribution,surface roughness and hardness of the formed parts are studied.Finally,a deep-drawn part with LDR=2.64 was successfully obtained through a pure titanium sheet with a grain size of d=8.4μm and a thickness of 200μm.