Shape Factors And Feasibility of an Industrial Product through Sheet Metal Hydroforming

Sheet metal hydroforming has gained an increasing interest around the world in automotive and aerospace industries. This non conventional metal forming process has many advantages that meet industrial needs in reality very well, such as: formability improvement, good surface quality, higher dimensional accuracy, reduction of springback amount compared with the conventional processes (1). Furthermore, the process chain could be simplified with considerable cost efficiency (2, 3). Through a research program, whose objective is to define specific rules in order to assess a macro-feasibility for a given hydroforming process, the authors have analyzed the influence of the process variables on sheet metal hydroforming by taking into account different types of geometries. The goal of this research, as described in this paperwork, is to implement a methodology that allows one to check the “macro” feasibility of a product through sheet metal hydroforming starting from simple considerations in the early stage of the process design (4). In this specific case, the developed methodology is characterized by the definition of a set of specifically designed “shape factors” and by their application on properly designed study cases. Their application can determine the feasible limits for a considered process set up condition. The definition of the shape factors and of each of their lower bounds has been drawn through an extensive numerical and experimental investigation on three different study cases which have been described in recent publications by the same authors (5, 6 and 7). In this paper the authors aim to describe and to check the developed methodology through “Fondello Fanale”, an application on an industrial test case characterized by a complex geometry. Starting from the geometry of the industrial test case, one can say that it is necessary to use more than one of the defined shape factors to analyze the product feasibility. On the considered component, the most critical areas have been chosen and the geometrical gradients of the shape have been taken into account by the authors. In each one of the considered areas, shape factors have been calculated and their value has been compared to their physical limits for the considered material and thickness. Thorough numerical and experimental investigation the shape factors analysis has given the opportunity to check the non-feasibility of the product. Further developments are related to the possibility, starting from the minimum values of the analyzed shape factors, to re-design the geometry of the product in order to reach its feasibility.