Study On Size Effects And Simulation Of H62 In Micro-forming Process

With the rapid development of the micro electro industry, as a new plastic forming technology, micro-forming is becoming more and more important due to the trend of miniaturization. Miniature parts have a wide application in spaceflight, precision electro apparatus, medical products and national defence and so on. But there are some problems that result form the process of miniaturization, and during micro-forming material will behave some characters which are different from normal manufacture process. Up to now, there is not any systemic theory to instruct the systematical research for micro-forming. In this thesis, the micro tensile properties of micro specimen of H62 are studied. The micro tensile experiment and numerical simulation are used to study the material property of H62 in micro-plastic-forming process, and a basic research of micro-deep drawing to find some characteristics and die design method is accomplished by numerical simulation, which might give a little instruction to the application of micro-deep.Micro-plastic-forming technology, size effects and its theoretical explanation are systematically introduced in this paper. Many experiments show that materials behave strong size effects when the characteristic length scale is in the order of millimeter or less than. Through micro tensile test of H62, the influences of the specimen width and thickness on tensile strength, ductibility and flow stress. The results show that, with a decrease of specimen width and thickness, the tensile strength, ductibility and material plastic property reduce, the extent of witch have some relationship with the ratio between surface area and volume. The results prove the existence of material characteristic size effects as well as the rationality of surface layer model.Making use of finite element technology, the software ABAUQS is used to study the deforming rules during the micro deep drawing process. In the numerical simulation, considering the effect of surface layer grain, blank model is built by delaminating. The influence of relative punch diameter, friction coefficient, die scale and holder force are studied by numerical simulation. The results show that, the deformation still presents geometrical comparability during the change of relative punch diameter, but its mechanism makes some difference. The results also present that, during the decrease of specimen scale, the friction increases and its mechanism makes change and the influence of friction plays an important role in the later half stage of deformation, and the influence of die scale and holder force in the former half stage.