Research On Drawing-flanging Deformation Mode Of Circular Plate With Center-hole

Because of different aperture in the circular plate with center-hole, there areseveral deformation modes in the forming process, such as pure deep drawing, purehole flanging and drawing-flanging compound forming. Deformation law of sheetmetal is grasped in essence through researching the whole forming process of circularplate with center-hole. Based on the obtained deformation law, the process can beeffectively controlled, so that the qualified parts can be produced with the mosteconomical blank shape and size, and production cost of the parts is reduced.The combinations of the metal plastic theory, finite element numerical analysisand experimental study are used as the methodology. The effect of pre-manufacturedhole size on sheet metal deformation mode in the forming process is studied bydiscussing the deformation process of a series of circular plates whose plate thicknessis2mm, the outside diameter is80mm, and diameter of pre-manufactured hole is0~45mm.The maximum radial stress of deformation zone of blank is the main basis forjudging deformation mode of circular plate with center-hole. Traditionally themaximum radial stress calculated by simplified solution can’t reflect the deformationmode of blank. The solving formulas of the maximum radial stress of deep drawingand hole flanging deformation zone are modified based on considering the effect ofmaterial hardening. The theoretical calculation model and change curve of themaximum radial stress in the forming process can be obtained, and the deformationmode can be predicted by comparing the two modified formulas. The analysis showsthat four deformation modes may be occurred in the forming process: pure deepdrawing, compound forming with deep drawing as main deformation mode,compound forming with hole flanging as main deformation mode and pure holeflanging. This research method is more scientific in theory, and is more reliable thananalyzing qualitatively deformation mode of plates just from the empiricalperspective.In order to preliminarily verify the accuracy of theoretical analysis, numericalsimulation software DYNAFORM is used to simulate and analyze the whole formingprocess of a series of circular plates whose plate thickness is2mm, the outsidediameter is80mm, and pre-manufactured hole diameter is respectively0、5、10、15、20、25、30、35、40、45/mm. The simulation results show that with increase of pre-manufactured hole diameter, the trend of deformation mode is: pure deep drawing�'compound forming with deep drawing as main deformation mode�'compoundforming with hole flanging as main deformation mode�'pure hole flanging. Thisconclusion agrees well with the theoretical analysis results.In order to fatherly verify the accuracy of theoretical analysis, experiments areconducted with the same size blank in this paper. The results show that with increaseof pre-manufactured hole diameter, deformation trend of blank is changed over frompure deep drawing to drawing-flanging compound forming; when pre-manufacturedhole diameter reaches a certain value, there is only pure hole flanging in thedeformation process. The results agree well with the results of theoretical analysis andnumerical simulation.The theoretical calculation model of radial stress in the deformation process ofcircular plate with center-hole is established in this paper, and is used to accuratelyjudge deformation mode of this kind of slab in the deformation process. This methodnot only enriches the theory of metal plastic forming, but also provides valuablereference for pressing technics of such parts.