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.
Study and Simulation of Critical Factors Affecting Final Quality in Electromagnetically Hemmed Automotive Aluminum
A previous study on electromagnetic forming (EM) hemming technology carried out in TECNALIA showed the real capability of this high speed deformation method to produce quality hemmed parts (Jimbert et al., J. Mater. Process. Technol. 211:916–924, 2011). Continuing with the development of this promising new application for the EM technology, some new experiments were run. The objective of this study is to focus on the critical processing factors that affect the final quality of the electromagnetically hemmed parts. For this purpose, an experimental plan was designed changing different input parameters and output quality parameters measured to quantify the results. The flange height limit was obtained for the studied experimental setup and was established at 10 mm. The bending radius and the gap between the inner and the outer part have to be keep to the minimum to increase final quality. In parallel to the physical experiments, EM hemming simulations were carried out using an EM loose coupling simulation method. An EM hemming process simulation of a circular whole part was carried out using shell elements. Results were compared with cross section simulations of the hemmed union using solid elements in order to analyze the importance of the type of element used for EM hemming simulation. Simulations revealed that solid elements reproduce quality aspects better than shell elements.
Surface roughness monitoring by singular spectrum analysis of vibration signals
Abstract This study assessed two methods for enhanced surface roughness (Ra) monitoring based on the application of singular spectrum analysis (SSA) to vibrations signals generated in workpiece-cutting tool interaction in CNC finish turning operations i.e., the individual analysis of principal components (I-SSA), and the grouping analysis of correlated principal components (G-SSA). Singular spectrum analysis is a non-parametric technique of time series analysis that decomposes a signal into a set of independent additive time series referred to as principal components. A number of experiments with different cutting conditions were performed to assess surface roughness monitoring using both of these methods. The results show that singular spectrum analysis of vibration signal processing discriminated the frequency ranges effective for predicting surface roughness. Grouping analysis of correlated principal components (G-SSA) proved to be the most efficient method for monitoring surface roughness, with optimum prediction and reliability results at a lower analytical-computational cost. Finally, the results show that singular spectrum analysis is an ideal method for analyzing vibration signals applied to the on-line monitoring of surface roughness.