Sheet Metal Hydroforming Process Review Through Shape Factors Analysis and Numerical Simulation

摘要

The increasing application of numerical simulation in metal forming field has helped engineers to solve problems one after another to manufacture a qualified formed product reducing the required time. Accurate simulation results are fundamental for the tooling and the product designs. Many factors can influence the final simulation result like for example a suitable yield criterion[1]. The wide application of numerical simulation is encouraging the development of highly accurate simulation procedures to meet industrial requirements. Currently,industrial goals of the forming simulation can be summarized in three main groups[2]: time reduction,costs reduction,increase of product quality. Many studies have been carried out about; materials,yield criteria[3] and plastic deformation[4,5],process parameters[6] and their optimization,geometry modifications of the stamped part to evaluate if modifications in the process responses are required,reaching the goal to perform a virtual tryout of the whole deformation process. Through a research program,whose aim is to define specific rules that allow to establish a macro-feasibility for a given hydroforming process,the authors have analyzed the influence of the process variables on sheet metal hydroforming taking into account different types of geometries. The goal of this research is to implement a methodology that allows to reach the feasibility of a product through sheet metal hydroforming starting from simple considerations in the early stage of the process design[7] In this specific case,the developed methodology is characterized by the definition of a set of "shape factors",purpose designed and by their application on various study cases. Their application can suggest the feasible limits for a considered process set up. Shape factors and their lower bounds have been defined through an extensive numerical and experimental in-vestigation on three different study cases,described in recent publications by the same authors[8]. In this paper the authors aim to check the developed methodology through an application on an industrial test case characterized by a complex geometry and called "Fondello Fanale". Starting from the geometry of the industrial test case,it is possible to say that more than one of the shape factors is needed to analyze the product feasibility. On the considered component the most critical areas have been chosen by the authors taking into account the component shape. In each one of the considered areas,the shape factors have been calculated and their value have been compared with their physical limit. The shape factors analysis has led to declare the no feasibility of the FF. In compliance with the shape factors rules three new and different geometries have been identified and numerically tested in order to verify their feasibility.