Flanging and Hemming of Auto Body Panels using the Electro Magnetic Forming technology
Electro Magnetic Forming (EMF) technology has a great number of potential applications for the automotive industry. LABEIN-Tecnalia has worked with this technology for six years and has a good understanding of the automotive industry’s needs and challenges. LABEIN-Tecnalia is currently developing new applications with EMF technology. Taking into account the advantages and limitations of EMF, bending and hemming processes present good geometric conditions for the use of this technology. The study presented is based largely on hemming circular configurations which are simplifications of those commonly used on hemmed automotive parts. The parameters of this new EMF bending and hemming processes have been studied, as well as their influence on the final quality of the parts obtained. Conclusions obtained from the basic geometries were tested on a more complicated geometry in order to apply the knowledge acquired. Parallel to the experimental work, fully coupled electromechanical software by LS-DYNA has been used to simulate and extend the present hemming results.
Processing and tooling considerations in joining by forming technologies; part A—mechanical joining
Joining by plastic deformation, also called joining by forming techniques, has been developed as a powerful tool for joining a broad range of similar and dissimilar materials in an environmentally friendly manner. Generally, the joining by forming techniques fall into two distinctive categories, namely mechanical joining and solid state welding. In this paper, different methods of joining by forming are studied from processing and manufacturing points of view. The article is arranged in three parts. Mechanical joining processes will be discussed in this part A. Various processes in this category have been addressed individually. Principles of the processing, applicable materials, process variants, joint mechanical behavior including static and dynamic performance, and various optimization techniques including experimental, numerical, and analytical approaches are the fields of concentration in this study.
Computer aided die design of straight flanging using approximate numerical analysis
Abstract Prediction of springback and minimum bending radius without failure are the main issues in die design for straight flanging process. The previously developed analytical and numerical models for sheet bending were observed to be inaccurate for straight flanging with relatively small bending radii. Finite element analysis with 2D models can be used to predict springback, bendability and tool loads accurately, but the analysis can take several hours, and pre- and post-processing are even more time consuming. Alternatively, in this paper, this problem is solved using advanced bending theory, implementing the geometric details of the straight flanging process to a mathematical model and computerized numerical analysis. The proposed method predicts springback and tool loads, particularly the minimum pad force necessary to prevent pad lift by dividing the deformation zone into three segments as pure elastic deflection without contact, elastic–plastic bending without contact and elastic–plastic bending in full contact with the die shoulder. The shift in neutral radius is modeled using an iterative procedure and taking the tool pressure and local thinning into account. The results are compared with limited experimental data as well as finite element simulations.