Basic Research Of Extrusion Forming Technology On Mid-thick Plate

Combined fine blanking,as an advanced precision plastic deformation process,has been widely applied in mid-thick plate structural components deformation field.A representative sheet metal deformation technology--sheet metal extrusion deformation technology,can form a lot of fine blanking parts features in the combined fine blanking and bulk forming technology,such as lug boss,embossment,countersink,etc..It’s significant to systematically study extrusion deformation technology on mid-thick plate for the combined fine blanking and bulk forming technology.This article therefore researches extrusion forming technology on mid-thick plate.Firstly flange’s lug boss deformation on mid-thick plate by extrusion has been researched.The finite element software was used to simulate flange extrusion deformation of 20 steel,6061 aluminium alloy and CDA110 copper alloy with 3mm in thickness.Metal flowing,distribution of stress-effective and strain-effective,damage and mesh distortion,etc.characteristics in flange forming process were analyzed.The effect of flange quality(rollover height and lug boss height)on process parameters,such as blank holder force,counter force,fillet radius of punch and die,diameter ratio of flange were studied,and the process parameters were optimized.Extrusion deformation experiments about 6061 aluminium alloy further demonstrate flange’s lug boss forming laws.Then lug boss backward extrusion deformation simulation of 20 steel medium plate(5mm in thickness)was implemented by finite element software,and material deformation characteristics in close die cavity,open die cavity and ajar die cavity were comparison analyzed.Study shows the relationship between sheet metal flowing laws,effective stress and effective strain distribution,load and stroke in three die cavities so that die cavity can be appropriately selected according to the relationship between load,lug boss height and punch-die stroke.Influences of factors such as punch-die corner radius,d/D(d=lug boss diameter,D=initial diameter of part),punch-die velocity on lug boss height were researched.The results of lug boss backward extrusion deformation in ajar cavity experiment proves accuracy of finite element simulation.In this paper,extrusion and backward extrusion deformation mechanism is studied on mid-thick plate and influence rules of factors on process parameters are revealed which have guiding significance for extrusion and backward extrusion deformation technology.