A Deep Drawing Technology With Micro-ball As Pressure Transmission Medium

Combination of metal forming theory, a deep drawing process with solid medium wasstudied. Micro-ball was used as micro-pressure transmission medium, alternating fluid mediumin this new forming process method. Small diameter steel ball was in discrete state, with freeflow characteristics and easy to be sealed.so Small diameter steel ball was suitable for pressuretransmission medium. However, Small diameter steel ball as solid medium, with friction of eachother, transfer different pressure to different direction, so it is different from hydroforming incontact pressure distribution and state in sheet metal forming, resulting in sheet metal formingpatterns and the stress state of material in which are different.In this paper, elastic-plastic mechanics principle of the forming process was used to analysestress distribution of each zone of the material and the strain distribution on every parts, so topredict risk. Explicit finite element analysis software eta/DYNAFORM was used to analysesheet metal forming and the micro-forming process was simulated. loading curve of pressure wasoptimized against the solid medium and the forming defects were predicted. Through theoreticalanalysis and finite element simulations show that some initial medium pressure can effectivelyreduce forming defects and improve the surface quality of formed parts. Setting appropriatemedia pressure can inhibit sheet thinning too much, reduce the risk of cross-section of the stressand improve the forming limit. So uniform thickness wall can be obtained.The existing forming theory was refered to design this soft-die forming device, which usesthe hydraulic system to provide the blank holder force. In this system electro-hydraulic servovalve can easily realize alterable blank holder force curve for the subsequent forming of theblank holder force study. Cylindrical cup deep drawing was compared by traditional drawing,and the reaction of media initial pressure to deep drawing was studied in series of tests. Resultsshow that: micro ball soft-die forming was greater than rigid-die deep drawing in forming limit.The maximum thinning of wall was24.16%, far less than traditional deep drawing27.6%;Setting initial medium pressure as2MPa can effectively improve the quality of tensile pieces.When optimized loading curve of Medium pressure was used, the limit drawing coefficient canreach to0.507for0.5mm thickness201plate.Stamping forming was used in a very wide range of industries field and all aspects of themanufacturing sector. Stamping forming achieved mainly through mold. It has high efficiency,high precision, good quality and low cost. It can save energy and raw materials. FollowingComplex shapes of parts and difficult workpieces emerged, so that complicate heavy stampingmolds were needed. Production cycle and commissioning need more and more time. On theother side, surface damage in traditional forming become more and more difficultly tolerance byworking conditions. Thus sheet metal stamping process have been disabled by aviation productswhich need high reliability. Hydroforming technology development and application can expandthe scope of stamping forming and simplify the structure of mold to save materials and time. Theflexibility of the liquid medium can avoid surface damage in forming process. The accuracy ofpart and surface quality were better. So it respond market demand well. But there were also lotsof limitations and lack, as pollution of the environment. Small diameter steel ball medium soft-die inherit rubber and hydraulic forming advantages. It is easy for small diameter steel ballto seal. It afford a new method for complex parts and hard formation part to be drawed.