Forming Process Research And Simulation Of Repetitive Deep Drawing Of Spherical Bottomed Conical Bodies

Sheet metal stamping forming plays an important role in the transportation manufacturing and civil industry,such as aerospace,automobile and ship building.In the manufacture of sheet metal products,it has been the focus of research that how to delay the failure and improve the forming limit.Repetitive deep drawing forming can restrain the local thinning of wall thickness of forming parts and realize approximate equal-thickness wall forming,at the same time,it can restrain the occurrence of flange wrinkling.So in this paper,the spherical bottom conical body is formed by repeated forming technology and finite element simulation and experiment research on this technology were carried out.Based on the repeated deep drawing forming technology designed,the 1-time deep drawing,2-time repetitive deep drawing,3-time repetitive deep drawing and 4-time repetitive deep drawing of spherical parts were simulated via Marc software,though which the curves of stress-strain and the variation curves of wall thickness in each phase of forming process were obtained and contrastively analyzed.According to the deformation characteristics of 2-time repetitive deep drawing forming of spherical bottom conical body and the finite element simulation results,the forming process is divided into four phases.Then theoretical analysis about the stress-strain changes of each phase was performed and the effect of repeated forming process on the flange wrinkling of spherical bottom conical part was studied by simulation.As a result,repetitive deep drawing can change the state of the stress and strain of forming process.It can also inhibit the reduction of wall thickness and then improve the forming limit and the wrinkling of flange can be effectively controlled by different repeated forming process.Experimental research of repeated deep drawing process were performed via Sheet forming testing machine,through which the curves of load-displacement and the formed parts were obtained.Comparing with the simulation results,we find the trend of these curves is basically the same.By measuring the wall thickness of the workpieces,we know the thickness of the wall thickness decreases gradually with the increase of the number of repetitive times.Measure the thickness of forming parts via Grid strain measurement,then you can get the distribution of strain,thickness,thinning rate and Forming Limit Diagram.Comparing these figures with the simulation results,experimental results were exactly the same as the simulation results,which further validated the feasibility of technology and the correctness of the simulation.