Multi Shape Sheet Hydroforming Tooling Design

Primo

et al. 2009

KEM

Sheet hydroforming has gained increasing interest in the automotive and aerospace industries because of its many advantages such as higher forming potentiality, good quality of the formed parts which may have complex geometry. The main advantage is that the uniform pressure can be transferred to any part of the formed blank at the same time [1]. In this paper, a “shape factors” set has been defined with the proper goal to understand if it can be used to help engineers to define “process rules” for the studied non conventional technology [2]. A specific prediction model, obtained thanks to a numerical factorial fractional plane, has been used in order to preview the process responses vs each defined shape factor. These shape factors have been used to track the process performances through their variation thanks to the usage of the numerical simulation that has been validated with an appropriate experimental campaign executed thanks to the usage of a specific equipment properly designed.

Section: Shape Factor Definitionmentioning

confidence: 99%

Feasibility Evaluation of Sheet Metal Hydroformed Components through Shape Factors Application

Primo

et al. 2009

KEM

“…In this specific case, a shape parameters set has been defined in order to orient the designer, within the process design space of a given "component family" [3][4][5][6].…”

mentioning

confidence: 99%

Sheet Metal Forming Process Design Rules Development

Primo

2011

KEM

Finite element analysis (FEA) is a powerful tool to evaluate the formability of stamping parts during process and die design development procedures. However, in order to achieve good product quality and process reliability, FEA application has to be performed many times exploring different process parameters combinations. Meanwhile, it is very difficult to perform an exhaustive process design definition when many parameters play a fundamental role to define such a complex problem. So, under the needs of reduction in: design time, development cost and parts weight, there is an urgent need to develop and apply more efficient methods in order to improve the current design procedures. For a generic component it is clear how its shape, among several parameters, has a direct influence on its feasibility. Starting from this assumption, the authors have developed a new approach grouping components upon their shapes analyzing component formability within a given “component family”. Nowadays, it exists only a process designer “sensitivity” that produces a ranking upon shape/feasibility ratio. Having as reference industrial test cases, the authors have defined appropriate shape parameters in order to have dimensionless coefficients representative for the given geometries. In particular, the components have been classified using a parameters set defining similarity families: related to geometrical aspects and to constitutive material. From the geometrical point of view the following parameters have been defined: family name, shape factor, punch radius-thickness ratio, die radius-thickness ratio, while for the constitutive material a code has been defined. FEA has been extensively used in order to: define, investigate and validate each shape parameter with a proper comparison to the macro feasibility of the chosen component geometry. The feasibility configuration definition, for a given shape, has been made through an appropriate study of the influence of each process variable on the properly process performances.

“…The physical and numerical experimentations were carried out on multiple geometries, different each others in punch radius and die radius, and on multiple materials, steel FeP04 (with a thickness of 1mm and 0,7mm) and Aluminum Al6061 (with a thickness of 0,7mm). The numerical simulation, validated by the experimental investigations [13,14], allowed to define a relationship, specific for sheet metal hydroforming, between the defined shape ratio and the key performance indicator, that is the percentage reduction thickness measured on specific areas of the formed part. The development of numerical models with an high level accuracy could give the real possibility to evaluate process feasibility with different combinations of geometrical and materials parameters without, at the first glance, simulation but only analyzing the specific curves (y = percentage reduction thickness, x = shape ratio).…”

mentioning

confidence: 99%

Process Performances Evaluation Using a Specific Shape Factor in the Case of Sheet Hydroforming

Anglani

2009

KEM

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 time required. 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, 4, 5] and plastic deformation [6, 7, 8], process parameters [9, 10, 11] and their optimization, geometry modification of the stamped part to evaluate if process responses modifications are required, reaching the goal to perform a virtual tryout of the whole deformation process [12]. In this paper proper metal forming numerical model and experimental analysis have been developed in order to foresee process responses in the case of sheet hydroforming technology. The interactions among the process performances and its variables are the most interesting aspects of the research because their knowledge means the possibility to drive the process feasibility which can be represented by the absence of ruptures and/or wrinkles in the stamped component. This paper analyzes the sheet thickness variation during the hydroforming process, according to a specifically defined “shape ratio”, useful to characterize product’s geometry. The latter is an hydroformed product characterized by a rectangular characteristic section with a drawing depth of 150mm, obtained by a hydroforming operation on a blank having a hexagonal shape. The physical and numerical experimentations were carried out on multiple geometries, different each others in punch radius and die radius, and on multiple materials, steel FeP04 (with a thickness of 1mm and 0,7mm) and Aluminum Al6061 (with a thickness of 0,7mm). The numerical simulation, validated by the experimental investigations [13,14], allowed to define a relationship, specific for sheet metal hydroforming, between the defined shape ratio and the key performance indicator, that is the percentage reduction thickness measured on specific areas of the formed part. The development of numerical models with an high level accuracy could give the real possibility to evaluate process feasibility with different combinations of geometrical and materials parameters without, at the first glance, simulation but only analyzing the specific curves (y = percentage reduction thickness, x = shape ratio).